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TCSH(1)                                                                                              TCSH(1)

       tcsh - C shell with file name completion and command line editing

       tcsh [-bcdefFimnqstvVxX] [-Dname[=value]] [arg ...]
       tcsh -l

       tcsh  is an enhanced but completely compatible version of the Berkeley UNIX C shell, csh(1).  It is a
       command language interpreter usable both as an interactive login shell and  a  shell  script  command
       processor.   It  includes a command-line editor (see The command-line editor), programmable word com-pletion completion
       pletion (see Completion and listing), spelling correction (see Spelling correction), a history mecha-nism mechanism
       nism  (see  History substitution), job control (see Jobs) and a C-like syntax.  The NEW FEATURES sec-tion section
       tion describes major enhancements of tcsh over csh(1).  Throughout this manual, features of tcsh  not
       found  in most csh(1) implementations (specifically, the 4.4BSD csh) are labeled with `(+)', and fea-tures features
       tures which are present in csh(1) but not usually documented are labeled with `(u)'.

   Argument list processing
       If the first argument (argument 0) to the shell is `-' then it is a login shell.  A login  shell  can
       be also specified by invoking the shell with the -l flag as the only argument.

       The rest of the flag arguments are interpreted as follows:

       -b  Forces  a  ``break'' from option processing, causing any further shell arguments to be treated as
           non-option arguments.  The remaining arguments will not be interpreted as  shell  options.   This
           may  be  used  to  pass  options to a shell script without confusion or possible subterfuge.  The
           shell will not run a set-user ID script without this option.

       -c  Commands are read from the following argument (which must be present, and must be a single  argu-ment), argument),
           ment), stored in the command shell variable for reference, and executed.  Any remaining arguments
           are placed in the argv shell variable.

       -d  The shell loads the directory stack from ~/.cshdirs as  described  under  Startup  and  shutdown,
           whether or not it is a login shell. (+)

           Sets the environment variable name to value. (Domain/OS only) (+)

       -e  The shell exits if any invoked command terminates abnormally or yields a non-zero exit status.

       -f  The shell ignores ~/.tcshrc, and thus starts faster.

       -F  The shell uses fork(2) instead of vfork(2) to spawn processes. (Convex/OS only) (+)

       -i  The shell is interactive and prompts for its top-level input, even if it appears to not be a ter-minal. terminal.
           minal.  Shells are interactive without this option if their inputs and outputs are terminals.

       -l  The shell is a login shell.  Applicable only if -l is the only flag specified.

       -m  The shell loads ~/.tcshrc even if it does not belong to the effective user.   Newer  versions  of
           su(1) can pass -m to the shell. (+)

       -n  The shell parses commands but does not execute them.  This aids in debugging shell scripts.

       -q  The  shell  accepts  SIGQUIT  (see Signal handling) and behaves when it is used under a debugger.
           Job control is disabled. (u)

       -s  Command input is taken from the standard input.

       -t  The shell reads and executes a single line of input.  A `\' may be used to escape the newline  at
           the end of this line and continue onto another line.

       -v  Sets the verbose shell variable, so that command input is echoed after history substitution.

       -x  Sets the echo shell variable, so that commands are echoed immediately before execution.

       -V  Sets the verbose shell variable even before executing ~/.tcshrc.

       -X  Is to -x as -V is to -v.

           Print a help message on the standard output and exit. (+)

           Print the version/platform/compilation options on the standard output and exit.  This information
           is also contained in the version shell variable. (+)

       After processing of flag arguments, if arguments remain but none of the -c, -i,  -s,  or  -t  options
       were  given, the first argument is taken as the name of a file of commands, or ``script'', to be exe-cuted. executed.
       cuted.  The shell opens this file and saves its name for possible resubstitution  by  `$0'.   Because
       many  systems  use either the standard version 6 or version 7 shells whose shell scripts are not com-patible compatible
       patible with this shell, the shell uses such a `standard' shell to execute a script whose first char-acter character
       acter is not a `#', i.e., that does not start with a comment.

       Remaining arguments are placed in the argv shell variable.

   Startup and shutdown
       A  login  shell begins by executing commands from the system files /etc/csh.cshrc and /etc/csh.login.
       It then executes commands from files in the  user's  home  directory:  first  ~/.tcshrc  (+)  or,  if
       ~/.tcshrc is not found, ~/.cshrc, then ~/.history (or the value of the histfile shell variable), then
       ~/.login, and finally ~/.cshdirs (or the value of the dirsfile shell variable) (+).   The  shell  may
       read  /etc/csh.login  before  instead  of  after /etc/csh.cshrc, and ~/.login before instead of after
       ~/.tcshrc or ~/.cshrc and ~/.history, if so compiled; see the version shell variable. (+)

       Non-login shells read only /etc/csh.cshrc and ~/.tcshrc or ~/.cshrc on startup.

       For examples of startup files, please consult

       Commands like stty(1) and tset(1), which need be run  only  once  per  login,  usually  go  in  one's
       ~/.login file.  Users who need to use the same set of files with both csh(1) and tcsh can have only a
       ~/.cshrc which checks for the existence of the tcsh shell variable (q.v.) before using  tcsh-specific
       commands,  or  can  have  both  a  ~/.cshrc  and  a ~/.tcshrc which sources (see the builtin command)
       ~/.cshrc.  The rest of this manual uses `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not found,

       In  the normal case, the shell begins reading commands from the terminal, prompting with `> '.  (Pro-
       cessing of arguments and the use of the  shell  to  process  files  containing  command  scripts  are
       described  later.)   The shell repeatedly reads a line of command input, breaks it into words, places
       it on the command history list, parses it and executes each command in the line.

       One can log out by typing `^D' on an empty line, `logout' or `login' or via  the  shell's  autologout
       mechanism  (see  the  autologout  shell  variable).  When a login shell terminates it sets the logout
       shell variable to `normal' or `automatic' as appropriate,  then  executes  commands  from  the  files
       /etc/csh.logout  and  ~/.logout.   The  shell  may drop DTR on logout if so compiled; see the version
       shell variable.

       The names of the system login and logout files vary from system to system for compatibility with dif-
       ferent csh(1) variants; see FILES.

       We  first  describe The command-line editor.  The Completion and listing and Spelling correction sec-
       tions describe two sets of functionality that are implemented as editor commands  but  which  deserve
       their  own  treatment.   Finally, Editor commands lists and describes the editor commands specific to
       the shell and their default bindings.

   The command-line editor (+)
       Command-line input can be edited using key sequences much like those used in GNU Emacs or vi(1).  The
       editor  is  active  only  when  the edit shell variable is set, which it is by default in interactive
       shells.  The bindkey builtin can display and change key bindings.  Emacs-style key bindings are  used
       by default (unless the shell was compiled otherwise; see the version shell variable), but bindkey can
       change the key bindings to vi-style bindings en masse.

       The shell always binds the arrow keys (as defined in the TERMCAP environment variable) to

           down    down-history
           up      up-history
           left    backward-char
           right   forward-char

       unless doing so would alter another single-character binding.  One  can  set  the  arrow  key  escape
       sequences  to  the  empty  string with settc to prevent these bindings.  The ANSI/VT100 sequences for
       arrow keys are always bound.

       Other key bindings are, for the most part, what Emacs and vi(1) users would expect and can easily  be
       displayed  by  bindkey, so there is no need to list them here.  Likewise, bindkey can list the editor
       commands with a short description of each.

       Note that editor commands do not have the same notion of a ``word'' as does the  shell.   The  editor
       delimits  words  with  any non-alphanumeric characters not in the shell variable wordchars, while the
       shell recognizes only whitespace and some of the characters with special meanings to it, listed under
       Lexical structure.

   Completion and listing (+)
       The shell is often able to complete words when given a unique abbreviation.  Type part of a word (for
       example `ls /usr/lost') and hit the tab key to run the complete-word editor command.  The shell  com-
       pletes  the  filename  `/usr/lost' to `/usr/lost+found/', replacing the incomplete word with the com-
       plete word in the input buffer.  (Note the terminal `/'; completion adds a `/' to  the  end  of  com-
       pleted  directories  and  a  space to the end of other completed words, to speed typing and provide a
       visual indicator of successful completion.  The addsuffix shell variable  can  be  unset  to  prevent
       this.)   If no match is found (perhaps `/usr/lost+found' doesn't exist), the terminal bell rings.  If
       the word is already complete (perhaps there is a `/usr/lost' on your  system,  or  perhaps  you  were
       thinking  too  far  ahead  and  typed the whole thing) a `/' or space is added to the end if it isn't
       already there.

       Completion works anywhere in the line, not at just the end; completed text pushes  the  rest  of  the
       line  to  the  right.  Completion in the middle of a word often results in leftover characters to the
       right of the cursor that need to be deleted.

       Commands and variables can be completed in much the same way.  For example,  typing  `em[tab]'  would
       complete  `em' to `emacs' if emacs were the only command on your system beginning with `em'.  Comple-
       tion can find a command in any directory in path or if given a full pathname.  Typing `echo $ar[tab]'
       would complete `$ar' to `$argv' if no other variable began with `ar'.

       The  shell  parses the input buffer to determine whether the word you want to complete should be com-
       pleted as a filename, command or variable.  The first word in the buffer and the first word following
       `;',  `|', `|&', `&&' or `||' is considered to be a command.  A word beginning with `$' is considered
       to be a variable.  Anything else is a filename.  An empty line is `completed' as a filename.

       You can list the possible completions of a word at any time by typing `^D' to run the delete-char-or-
       list-or-eof  editor  command.  The shell lists the possible completions using the ls-F builtin (q.v.)
       and reprints the prompt and unfinished command line, for example:

           > ls /usr/l[^D]
           lbin/       lib/        local/      lost+found/
           > ls /usr/l

       If the autolist shell variable is set, the shell lists the remaining choices (if any)  whenever  com-
       pletion fails:

           > set autolist
           > nm /usr/lib/libt[tab]
           libtermcap.a@ libtermlib.a@
           > nm /usr/lib/libterm

       If  autolist  is  set  to  `ambiguous', choices are listed only when completion fails and adds no new
       characters to the word being completed.

       A filename to be completed can contain variables, your own or others'  home  directories  abbreviated
       with  `~' (see Filename substitution) and directory stack entries abbreviated with `=' (see Directory
       stack substitution).  For example,

           > ls ~k[^D]
           kahn    kas     kellogg
           > ls ~ke[tab]
           > ls ~kellogg/


           > set local = /usr/local
           > ls $lo[tab]
           > ls $local/[^D]
           bin/ etc/ lib/ man/ src/
           > ls $local/

       Note that variables can also be expanded explicitly with the expand-variables editor command.

       delete-char-or-list-or-eof lists at only the end of the line; in the middle of a line it deletes  the
       character  under  the cursor and on an empty line it logs one out or, if ignoreeof is set, does noth-
       ing.  `M-^D', bound to the editor command list-choices, lists completion possibilities anywhere on  a
       line,  and  list-choices  (or  any  one  of the related editor commands that do or don't delete, list
       and/or log out, listed under delete-char-or-list-or-eof) can  be  bound  to  `^D'  with  the  bindkey
       builtin command if so desired.

       The  complete-word-fwd  and complete-word-back editor commands (not bound to any keys by default) can
       be used to cycle up and down through the list of possible completions,  replacing  the  current  word
       with the next or previous word in the list.

       The  shell  variable  fignore can be set to a list of suffixes to be ignored by completion.  Consider
       the following:

           > ls
           Makefile        condiments.h~   main.o          side.c
           README          main.c          meal            side.o
           condiments.h    main.c~
           > set fignore = (.o \~)
           > emacs ma[^D]
           main.c   main.c~  main.o
           > emacs ma[tab]
           > emacs main.c

       `main.c~' and `main.o' are ignored by completion (but not listing), because they end in  suffixes  in
       fignore.   Note  that  a  `\' was needed in front of `~' to prevent it from being expanded to home as
       described under Filename substitution.  fignore is ignored if only one completion is possible.

       If the complete shell variable is set to `enhance', completion 1) ignores case and 2) considers peri-
       ods,  hyphens and underscores (`.', `-' and `_') to be word separators and hyphens and underscores to
       be equivalent.  If you had the following files

           comp.lang.c      comp.lang.perl   comp.std.c++
           comp.lang.c++    comp.std.c

       and typed `mail -f c.l.c[tab]', it would be completed to `mail -f comp.lang.c',  and  ^D  would  list
       `comp.lang.c'   and   `comp.lang.c++'.    `mail   -f   c..c++[^D]'  would  list  `comp.lang.c++'  and
       `comp.std.c++'.  Typing `rm a--file[^D]' in the following directory

           A_silly_file    a-hyphenated-file    another_silly_file

       would list all three files, because case is ignored  and  hyphens  and  underscores  are  equivalent.
       Periods, however, are not equivalent to hyphens or underscores.

       Completion and listing are affected by several other shell variables: recexact can be set to complete
       on the shortest possible unique match, even if more typing might result in a longer match:

           > ls
           fodder   foo      food     foonly
           > set recexact
           > rm fo[tab]

       just beeps, because `fo' could expand to `fod' or `foo', but if we type another `o',

           > rm foo[tab]
           > rm foo

       the completion completes on `foo', even though `food' and `foonly' also match.  autoexpand can be set
       to  run  the  expand-history editor command before each completion attempt, autocorrect can be set to
       spelling-correct the word to be completed (see Spelling correction) before  each  completion  attempt
       and  correct can be set to complete commands automatically after one hits `return'.  matchbeep can be
       set to make completion beep or not beep in a variety of situations, and nobeep can be  set  to  never
       beep  at  all.   nostat can be set to a list of directories and/or patterns that match directories to
       prevent the completion mechanism from stat(2)ing those directories.  listmax and listmaxrows  can  be
       set  to limit the number of items and rows (respectively) that are listed without asking first.  rec-
       ognize_only_executables can be set to make the shell list only executables when listing commands, but
       it is quite slow.

       Finally,  the complete builtin command can be used to tell the shell how to complete words other than
       filenames, commands and variables.  Completion and listing do not work on glob-patterns (see Filename
       substitution),  but  the  list-glob  and expand-glob editor commands perform equivalent functions for

   Spelling correction (+)
       The shell can sometimes correct the spelling of filenames, commands and variable  names  as  well  as
       completing and listing them.

       Individual  words  can be spelling-corrected with the spell-word editor command (usually bound to M-s
       and M-S) and the entire input buffer with spell-line (usually bound to M-$).  The correct shell vari-
       able  can  be  set to `cmd' to correct the command name or `all' to correct the entire line each time
       return is typed, and autocorrect can be set to correct the word to be completed before  each  comple-
       tion attempt.

       When  spelling  correction  is invoked in any of these ways and the shell thinks that any part of the
       command line is misspelled, it prompts with the corrected line:

           > set correct = cmd
           > lz /usr/bin
           CORRECT>ls /usr/bin (y|n|e|a)?

       One can answer `y' or space to execute the corrected line, `e' to leave the  uncorrected  command  in
       the  input buffer, `a' to abort the command as if `^C' had been hit, and anything else to execute the
       original line unchanged.

       Spelling correction recognizes user-defined completions (see the complete builtin  command).   If  an
       input  word  in a position for which a completion is defined resembles a word in the completion list,
       spelling correction registers a misspelling and suggests the latter word as a  correction.   However,
       if  the input word does not match any of the possible completions for that position, spelling correc-
       tion does not register a misspelling.

       Like completion, spelling correction works anywhere in the line, pushing the rest of the line to  the
       right and possibly leaving extra characters to the right of the cursor.

       Beware:  spelling correction is not guaranteed to work the way one intends, and is provided mostly as
       an experimental feature.  Suggestions and improvements are welcome.

   Editor commands (+)
       `bindkey' lists key bindings and `bindkey -l' lists and briefly describes editor commands.  Only  new
       or  especially  interesting  editor commands are described here.  See emacs(1) and vi(1) for descrip-
       tions of each editor's key bindings.

       The character or characters to which each command is  bound  by  default  is  given  in  parentheses.
       `^character'  means a control character and `M-character' a meta character, typed as escape-character
       on terminals without a meta key.  Case counts, but commands that are bound to letters by default  are
       bound to both lower- and uppercase letters for convenience.

       complete-word (tab)
               Completes a word as described under Completion and listing.

       complete-word-back (not bound)
               Like complete-word-fwd, but steps up from the end of the list.

       complete-word-fwd (not bound)
               Replaces  the  current  word with the first word in the list of possible completions.  May be
               repeated to step down through the list.  At the end of the list, beeps  and  reverts  to  the
               incomplete word.

       complete-word-raw (^X-tab)
               Like complete-word, but ignores user-defined completions.

       copy-prev-word (M-^_)
               Copies  the  previous  word in the current line into the input buffer.  See also insert-last-

       dabbrev-expand (M-/)
               Expands the current word to the most recent preceding one for which the current is a  leading
               substring,  wrapping  around  the history list (once) if necessary.  Repeating dabbrev-expand
               without any intervening typing changes to the next previous  word  etc.,  skipping  identical
               matches much like history-search-backward does.

       delete-char (not bound)
               Deletes the character under the cursor.  See also delete-char-or-list-or-eof.

       delete-char-or-eof (not bound)
               Does  delete-char  if  there is a character under the cursor or end-of-file on an empty line.
               See also delete-char-or-list-or-eof.

       delete-char-or-list (not bound)
               Does delete-char if there is a character under the cursor or list-choices at the end  of  the
               line.  See also delete-char-or-list-or-eof.

       delete-char-or-list-or-eof (^D)
               Does  delete-char  if  there  is a character under the cursor, list-choices at the end of the
               line or end-of-file on an empty line.  See also those three commands, each of which does only
               a  single  action, and delete-char-or-eof, delete-char-or-list and list-or-eof, each of which
               does a different two out of the three.

       down-history (down-arrow, ^N)
               Like up-history, but steps down, stopping at the original input line.

       end-of-file (not bound)
               Signals an end of file, causing the shell to exit unless the ignoreeof shell variable  (q.v.)
               is set to prevent this.  See also delete-char-or-list-or-eof.

       expand-history (M-space)
               Expands  history  substitutions  in  the  current  word.  See History substitution.  See also
               magic-space, toggle-literal-history and the autoexpand shell variable.

       expand-glob (^X-*)
               Expands the glob-pattern to the left of the cursor.  See Filename substitution.

       expand-line (not bound)
               Like expand-history, but expands history substitutions in each word in the input buffer,

       expand-variables (^X-$)
               Expands the variable to the left of the cursor.  See Variable substitution.

       history-search-backward (M-p, M-P)
               Searches backwards through the history list for a command beginning with the current contents
               of  the input buffer up to the cursor and copies it into the input buffer.  The search string
               may be a glob-pattern (see Filename substitution) containing `*', `?', `[]' or `{}'.  up-his-
               tory  and  down-history  will  proceed from the appropriate point in the history list.  Emacs
               mode only.  See also history-search-forward and i-search-back.

       history-search-forward (M-n, M-N)
               Like history-search-backward, but searches forward.

       i-search-back (not bound)
               Searches backward like history-search-backward, copies the first match into the input  buffer
               with  the cursor positioned at the end of the pattern, and prompts with `bck: ' and the first
               match.  Additional characters may be typed to extend the search, i-search-back may  be  typed
               to  continue  searching with the same pattern, wrapping around the history list if necessary,
               (i-search-back must be bound to a single character for this to work) or one of the  following
               special characters may be typed:

                   ^W      Appends the rest of the word under the cursor to the search pattern.
                   delete (or any character bound to backward-delete-char)
                           Undoes  the  effect  of the last character typed and deletes a character from the
                           search pattern if appropriate.
                   ^G      If the previous search was successful, aborts the entire search.   If  not,  goes
                           back to the last successful search.
                   escape  Ends the search, leaving the current line in the input buffer.

               Any  other character not bound to self-insert-command terminates the search, leaving the cur-
               rent line in the input buffer, and is then interpreted as normal  input.   In  particular,  a
               carriage return causes the current line to be executed.  Emacs mode only.  See also i-search-
               fwd and history-search-backward.

       i-search-fwd (not bound)
               Like i-search-back, but searches forward.

       insert-last-word (M-_)
               Inserts the last word of the previous input line (`!$') into  the  input  buffer.   See  also

       list-choices (M-^D)
               Lists  completion  possibilities as described under Completion and listing.  See also delete-
               char-or-list-or-eof and list-choices-raw.

       list-choices-raw (^X-^D)
               Like list-choices, but ignores user-defined completions.

       list-glob (^X-g, ^X-G)
               Lists (via the ls-F builtin) matches to the glob-pattern (see Filename substitution)  to  the
               left of the cursor.

       list-or-eof (not bound)
               Does list-choices or end-of-file on an empty line.  See also delete-char-or-list-or-eof.

       magic-space (not bound)
               Expands  history substitutions in the current line, like expand-history, and inserts a space.
               magic-space is designed to be bound to the space bar, but is not bound by default.

       normalize-command (^X-?)
               Searches for the current word in PATH and, if it is found, replaces it with the full path  to
               the executable.  Special characters are quoted.  Aliases are expanded and quoted but commands
               within aliases are not.  This command is useful with commands that  take  commands  as  argu-
               ments, e.g., `dbx' and `sh -x'.

       normalize-path (^X-n, ^X-N)
               Expands  the current word as described under the `expand' setting of the symlinks shell vari-

       overwrite-mode (unbound)
               Toggles between input and overwrite modes.

       run-fg-editor (M-^Z)
               Saves the current input line and looks for a stopped job with a name equal to the last compo-
               nent  of  the file name part of the EDITOR or VISUAL environment variables, or, if neither is
               set, `ed' or `vi'.  If such a job is found, it is restarted as if `fg %job' had  been  typed.
               This  is  used  to toggle back and forth between an editor and the shell easily.  Some people
               bind this command to `^Z' so they can do this even more easily.

       run-help (M-h, M-H)
               Searches for documentation on the current command, using the same notion of `current command'
               as  the  completion  routines,  and  prints  it.  There is no way to use a pager; run-help is
               designed for short help files.  If the special alias helpcommand is defined, it is  run  with
               the  command  name  as  a  sole argument.  Else, documentation should be in a file named com-
     , command.1, command.6, command.8 or command, which should be in one of the directo-
               ries  listed in the HPATH environment variable.  If there is more than one help file only the
               first is printed.

       self-insert-command (text characters)
               In insert mode (the default), inserts the typed character into the input line after the char-
               acter  under the cursor.  In overwrite mode, replaces the character under the cursor with the
               typed character.  The input mode is normally preserved between lines, but the inputmode shell
               variable  can  be set to `insert' or `overwrite' to put the editor in that mode at the begin-
               ning of each line.  See also overwrite-mode.

       sequence-lead-in (arrow prefix, meta prefix, ^X)
               Indicates that the following characters are part of a multi-key sequence.  Binding a  command
               to  a multi-key sequence really creates two bindings: the first character to sequence-lead-in
               and the whole sequence to the command.  All sequences beginning with  a  character  bound  to
               sequence-lead-in are effectively bound to undefined-key unless bound to another command.

       spell-line (M-$)
               Attempts  to  correct  the  spelling  of  each word in the input buffer, like spell-word, but
               ignores words whose first character is one of `-', `!', `^' or `%', or which contain `\', `*'
               or  `?',  to  avoid problems with switches, substitutions and the like.  See Spelling correc-

       spell-word (M-s, M-S)
               Attempts to correct the spelling of the current word as described under Spelling  correction.
               Checks each component of a word which appears to be a pathname.

       toggle-literal-history (M-r, M-R)
               Expands  or  `unexpands'  history substitutions in the input buffer.  See also expand-history
               and the autoexpand shell variable.

       undefined-key (any unbound key)

       up-history (up-arrow, ^P)
               Copies the previous entry in the history list into the input buffer.  If histlit is set, uses
               the literal form of the entry.  May be repeated to step up through the history list, stopping
               at the top.

       vi-search-back (?)
               Prompts with `?' for a search string (which may be a glob-pattern,  as  with  history-search-
               backward),  searches  for it and copies it into the input buffer.  The bell rings if no match
               is found.  Hitting return ends the search and leaves the last  match  in  the  input  buffer.
               Hitting escape ends the search and executes the match.  vi mode only.

       vi-search-fwd (/)
               Like vi-search-back, but searches forward.

       which-command (M-?)
               Does  a  which  (see  the  description of the builtin command) on the first word of the input

       yank-pop (M-y)
               When executed immediately after a yank or another yank-pop, replaces the yanked  string  with
               the  next  previous  string from the killring. This also has the effect of rotating the kill-
               ring, such that this string will be considered the most recently killed by a later yank  com-
               mand. Repeating yank-pop will cycle through the killring any number of times.

   Lexical structure
       The  shell  splits  input lines into words at blanks and tabs.  The special characters `&', `|', `;',
       `<', `>', `(', and `)' and the doubled characters `&&', `||',  `<<'  and  `>>'  are  always  separate
       words, whether or not they are surrounded by whitespace.

       When  the  shell's  input is not a terminal, the character `#' is taken to begin a comment.  Each `#'
       and the rest of the input line on which it appears is discarded before further parsing.

       A special character (including a blank or tab) may be prevented from having its special meaning,  and
       possibly  made part of another word, by preceding it with a backslash (`\') or enclosing it in single
       (`''), double (`"') or backward (``') quotes.  When not otherwise quoted a newline preceded by a  `\'
       is equivalent to a blank, but inside quotes this sequence results in a newline.

       Furthermore,  all Substitutions (see below) except History substitution can be prevented by enclosing
       the strings (or parts of strings) in which they appear with single quotes or by quoting  the  crucial
       character(s)  (e.g.,  `$' or ``' for Variable substitution or Command substitution respectively) with
       `\'.  (Alias substitution is no exception: quoting in any way any character of a word  for  which  an
       alias  has  been defined prevents substitution of the alias.  The usual way of quoting an alias is to
       precede it with a backslash.) History substitution is prevented by  backslashes  but  not  by  single
       quotes.  Strings quoted with double or backward quotes undergo Variable substitution and Command sub-
       stitution, but other substitutions are prevented.

       Text inside single or double quotes becomes a single word (or part of one).  Metacharacters in  these
       strings,  including  blanks and tabs, do not form separate words.  Only in one special case (see Com-
       mand substitution below) can a double-quoted string yield parts of more than one word;  single-quoted
       strings  never  do.   Backward quotes are special: they signal Command substitution (q.v.), which may
       result in more than one word.

       Quoting complex strings, particularly strings which themselves contain  quoting  characters,  can  be
       confusing.   Remember that quotes need not be used as they are in human writing!  It may be easier to
       quote not an entire string, but only those parts of the string which need  quoting,  using  different
       types of quoting to do so if appropriate.

       The  backslash_quote  shell variable (q.v.) can be set to make backslashes always quote `\', `'', and
       `"'.  (+) This may make complex quoting tasks easier, but  it  can  cause  syntax  errors  in  csh(1)

       We  now  describe  the  various transformations the shell performs on the input in the order in which
       they occur.  We note in passing the data structures involved and the  commands  and  variables  which
       affect  them.   Remember  that  substitutions  can be prevented by quoting as described under Lexical

   History substitution
       Each command, or ``event'', input from the terminal is saved in the history list.  The previous  com-
       mand  is  always  saved, and the history shell variable can be set to a number to save that many com-
       mands.  The histdup shell variable can be set to not save duplicate events or  consecutive  duplicate

       Saved  commands are numbered sequentially from 1 and stamped with the time.  It is not usually neces-
       sary to use event numbers, but the current event number can be made part of the prompt by placing  an
       `!' in the prompt shell variable.

       The  shell  actually  saves history in expanded and literal (unexpanded) forms.  If the histlit shell
       variable is set, commands that display and store history use the literal form.

       The history builtin command can print, store in a file, restore and clear the  history  list  at  any
       time, and the savehist and histfile shell variables can be can be set to store the history list auto-
       matically on logout and restore it on login.

       History substitutions introduce words from the history list into the input stream, making it easy  to
       repeat  commands, repeat arguments of a previous command in the current command, or fix spelling mis-
       takes in the previous command with little typing and a high degree of confidence.

       History substitutions begin with the character `!'.  They may begin anywhere in the input stream, but
       they  do not nest.  The `!' may be preceded by a `\' to prevent its special meaning; for convenience,
       a `!' is passed unchanged when it is followed by a blank, tab, newline, `=' or `('.  History  substi-
       tutions  also  occur when an input line begins with `^'.  This special abbreviation will be described
       later.  The characters used to signal history substitution (`!' and `^') can be  changed  by  setting
       the histchars shell variable.  Any input line which contains a history substitution is printed before
       it is executed.

       A history substitution may have an ``event specification'', which  indicates  the  event  from  which
       words  are  to be taken, a ``word designator'', which selects particular words from the chosen event,
       and/or a ``modifier'', which manipulates the selected words.

       An event specification can be

           n       A number, referring to a particular event
           -n      An offset, referring to the event n before the current event
           #       The current event.  This should be used carefully in csh(1), where there is no check  for
                   recursion.  tcsh allows 10 levels of recursion.  (+)
           !       The previous event (equivalent to `-1')
           s       The most recent event whose first word begins with the string s
           ?s?     The  most  recent event which contains the string s.  The second `?' can be omitted if it
                   is immediately followed by a newline.

       For example, consider this bit of someone's history list:

            9  8:30    nroff -man
           10  8:31    cp
           11  8:36    vi
           12  8:37    diff

       The commands are shown with their event numbers and time stamps.  The current event, which we haven't
       typed  in  yet,  is event 13.  `!11' and `!-2' refer to event 11.  `!!' refers to the previous event,
       12.  `!!' can be abbreviated `!' if it is followed by `:' (`:' is described below).  `!n'  refers  to
       event  9,  which  begins  with `n'.  `!?old?' also refers to event 12, which contains `old'.  Without
       word designators or modifiers history references simply expand to the entire event, so we might  type
       `!cp'  to redo the copy command or `!!|more' if the `diff' output scrolled off the top of the screen.

       History references may be insulated from the surrounding text with braces if necessary.  For example,
       `!vdoc'  would  look  for  a  command  beginning with `vdoc', and, in this example, not find one, but
       `!{v}doc' would expand unambiguously to `vi wumpus.mandoc'.  Even in braces, history substitutions do
       not nest.

       (+)  While  csh(1)  expands,  for  example, `!3d' to event 3 with the letter `d' appended to it, tcsh
       expands it to the last event beginning with `3d'; only completely numeric arguments  are  treated  as
       event  numbers.   This makes it possible to recall events beginning with numbers.  To expand `!3d' as
       in csh(1) say `!\3d'.

       To select words from an event we can follow the event specification by a `:' and a designator for the
       desired  words.   The  words  of  an input line are numbered from 0, the first (usually command) word
       being 0, the second word (first argument) being 1, etc.  The basic word designators are:

           0       The first (command) word
           n       The nth argument
           ^       The first argument, equivalent to `1'
           $       The last argument
           %       The word matched by an ?s? search
           x-y     A range of words
           -y      Equivalent to `0-y'
           *       Equivalent to `^-$', but returns nothing if the event contains only 1 word
           x*      Equivalent to `x-$'
           x-      Equivalent to `x*', but omitting the last word (`$')

       Selected words are inserted into the command line separated  by  single  blanks.   For  example,  the
       `diff'  command  in the previous example might have been typed as `diff !!:1.old !!:1' (using `:1' to
       select the first argument from the previous event) or `diff !-2:2 !-2:1' to select and swap the argu-
       ments  from  the  `cp'  command.   If we didn't care about the order of the `diff' we might have said
       `diff !-2:1-2' or simply `diff !-2:*'.  The `cp' command  might  have  been  written  `cp
       !#:1.old',  using  `#'  to  refer  to the current event.  `!n:-' would reuse the first two
       words from the `nroff' command to say `nroff -man'.

       The `:' separating the event specification from the word designator can be omitted  if  the  argument
       selector  begins  with  a `^', `$', `*', `%' or `-'.  For example, our `diff' command might have been
       `diff !!^.old !!^' or, equivalently, `diff !!$.old !!$'.  However, if `!!'  is  abbreviated  `!',  an
       argument selector beginning with `-' will be interpreted as an event specification.

       A  history  reference  may have a word designator but no event specification.  It then references the
       previous command.  Continuing our `diff' example, we could have said simply `diff !^.old !^'  or,  to
       get the arguments in the opposite order, just `diff !*'.

       The  word or words in a history reference can be edited, or ``modified'', by following it with one or
       more modifiers, each preceded by a `:':

           h       Remove a trailing pathname component, leaving the head.
           t       Remove all leading pathname components, leaving the tail.
           r       Remove a filename extension `.xxx', leaving the root name.
           e       Remove all but the extension.
           u       Uppercase the first lowercase letter.
           l       Lowercase the first uppercase letter.
           s/l/r/  Substitute l for r.  l is simply a string like r, not a  regular  expression  as  in  the
                   eponymous  ed(1)  command.  Any character may be used as the delimiter in place of `/'; a
                   `\' can be used to quote the delimiter inside l and r.  The character `&'  in  the  r  is
                   replaced  by l; `\' also quotes `&'.  If l is empty (``''), the l from a previous substi-
                   tution or the s from a previous `?s?' event specification is used.  The  trailing  delim-
                   iter may be omitted if it is immediately followed by a newline.
           &       Repeat the previous substitution.
           g       Apply the following modifier once to each word.
           a (+)   Apply the following modifier as many times as possible to a single word.  `a' and `g' can
                   be used together to apply a modifier globally.  In the current implementation, using  the
                   `a'  and  `s'  modifiers together can lead to an infinite loop.  For example, `:as/f/ff/'
                   will never terminate.  This behavior might change in the future.
           p       Print the new command line but do not execute it.
           q       Quote the substituted words, preventing further substitutions.
           x       Like q, but break into words at blanks, tabs and newlines.

       Modifiers are applied to only the first modifiable word (unless `g' is used).  It is an error for  no
       word to be modifiable.

       For example, the `diff' command might have been written as `diff !#^:r', using `:r' to
       remove `.old' from the first argument on the same line (`!#^').  We could say `echo hello out there',
       then  `echo  !*:u' to capitalize `hello', `echo !*:au' to say it out loud, or `echo !*:agu' to really
       shout.  We might follow `mail -s "I forgot my password"  rot'  with  `!:s/rot/root'  to  correct  the
       spelling of `root' (but see Spelling correction for a different approach).

       There  is  a special abbreviation for substitutions.  `^', when it is the first character on an input
       line, is equivalent to `!:s^'.  Thus we might have said `^rot^root' to make the  spelling  correction
       in  the previous example.  This is the only history substitution which does not explicitly begin with

       (+) In csh as such, only one modifier may be applied to each history or variable expansion.  In tcsh,
       more than one may be used, for example

           % mv /usr/man/man1/wumpus.1
           % man !$:t:r
           man wumpus

       In  csh,  the  result would be `wumpus.1:r'.  A substitution followed by a colon may need to be insu-
       lated from it with braces:

           > mv a.out /usr/games/wumpus
           > setenv PATH !$:h:$PATH
           Bad ! modifier: $.
           > setenv PATH !{-2$:h}:$PATH
           setenv PATH /usr/games:/bin:/usr/bin:.

       The first attempt would succeed in csh but fails in tcsh, because tcsh expects another modifier after
       the second colon rather than `$'.

       Finally,  history  can  be  accessed  through  the  editor  as well as through the substitutions just
       described.  The up- and down-history, history-search-backward and -forward, i-search-back  and  -fwd,
       vi-search-back and -fwd, copy-prev-word and insert-last-word editor commands search for events in the
       history list and copy them into the input buffer.  The toggle-literal-history editor command switches
       between  the  expanded  and  literal  forms of history lines in the input buffer.  expand-history and
       expand-line expand history substitutions in the current word and in the entire input  buffer  respec-

   Alias substitution
       The  shell  maintains  a list of aliases which can be set, unset and printed by the alias and unalias
       commands.  After a command line is parsed into simple commands (see Commands) the first word of  each
       command,  left-to-right,  is checked to see if it has an alias.  If so, the first word is replaced by
       the alias.  If the alias contains a history reference, it undergoes History  substitution  (q.v.)  as
       though  the  original  command were the previous input line.  If the alias does not contain a history
       reference, the argument list is left untouched.

       Thus if the alias for `ls' were `ls -l' the command `ls /usr' would become `ls -l /usr', the argument
       list here being undisturbed.  If the alias for `lookup' were `grep !^ /etc/passwd' then `lookup bill'
       would become `grep bill /etc/passwd'.  Aliases can be used to introduce parser metasyntax.  For exam-
       ple,  `alias  print 'pr \!* | lpr'' defines a ``command'' (`print') which pr(1)s its arguments to the
       line printer.

       Alias substitution is repeated until the first word of the command has no alias.  If an alias substi-
       tution  does  not change the first word (as in the previous example) it is flagged to prevent a loop.
       Other loops are detected and cause an error.

       Some aliases are referred to by the shell; see Special aliases.

   Variable substitution
       The shell maintains a list of variables, each of which has as value a list of  zero  or  more  words.
       The values of shell variables can be displayed and changed with the set and unset commands.  The sys-
       tem maintains its own list of ``environment'' variables.  These can be  displayed  and  changed  with
       printenv, setenv and unsetenv.

       (+)  Variables may be made read-only with `set -r' (q.v.)  Read-only variables may not be modified or
       unset; attempting to do so will cause an error.  Once made  read-only,  a  variable  cannot  be  made
       writable, so `set -r' should be used with caution.  Environment variables cannot be made read-only.

       Some  variables  are  set  by  the shell or referred to by it.  For instance, the argv variable is an
       image of the shell's argument list, and words of this variable's value are  referred  to  in  special
       ways.  Some of the variables referred to by the shell are toggles; the shell does not care what their
       value is, only whether they are set or not.  For instance, the verbose variable  is  a  toggle  which
       causes  command  input  to  be echoed.  The -v command line option sets this variable.  Special shell
       variables lists all variables which are referred to by the shell.

       Other operations treat variables numerically.  The `@' command permits  numeric  calculations  to  be
       performed and the result assigned to a variable.  Variable values are, however, always represented as
       (zero or more) strings.  For the purposes of numeric operations, the null string is considered to  be
       zero, and the second and subsequent words of multi-word values are ignored.

       After  the  input line is aliased and parsed, and before each command is executed, variable substitu-
       tion is performed keyed by `$' characters.  This expansion can be prevented by preceding the `$' with
       a  `\'  except  within  `"'s  where it always occurs, and within `''s where it never occurs.  Strings
       quoted by ``' are interpreted later (see Command substitution below) so  `$'  substitution  does  not
       occur  there  until later, if at all.  A `$' is passed unchanged if followed by a blank, tab, or end-

       Input/output redirections are recognized before variable expansion, and are variable  expanded  sepa-
       rately.  Otherwise, the command name and entire argument list are expanded together.  It is thus pos-
       sible for the first (command) word (to this point) to generate more than one word, the first of which
       becomes the command name, and the rest of which become arguments.

       Unless enclosed in `"' or given the `:q' modifier the results of variable substitution may eventually
       be command and filename substituted.  Within `"', a variable whose value consists of  multiple  words
       expands  to a (portion of a) single word, with the words of the variable's value separated by blanks.
       When the `:q' modifier is applied to a substitution the variable will expand to multiple  words  with
       each word separated by a blank and quoted to prevent later command or filename substitution.

       The  following  metasequences  are  provided  for  introducing  variable values into the shell input.
       Except as noted, it is an error to reference a variable which is not set.

       ${name} Substitutes the words of the value of variable name, each separated by a blank.  Braces insu-
               late  name  from  following  characters which would otherwise be part of it.  Shell variables
               have names consisting of up to 20 letters and digits starting with a letter.  The  underscore
               character  is  considered a letter.  If name is not a shell variable, but is set in the envi-
               ronment, then that value is returned (but `:' modifiers and the other forms given  below  are
               not available in this case).
               Substitutes only the selected words from the value of name.  The selector is subjected to `$'
               substitution and may consist of a single number or two numbers separated by a `-'.  The first
               word  of  a  variable's  value is numbered `1'.  If the first number of a range is omitted it
               defaults to `1'.  If the last member of a range is omitted  it  defaults  to  `$#name'.   The
               selector  `*'  selects  all  words.  It is not an error for a range to be empty if the second
               argument is omitted or in range.
       $0      Substitutes the name of the file from which command input is being read.  An error occurs  if
               the name is not known.
               Equivalent to `$argv[number]'.
       $*      Equivalent to `$argv', which is equivalent to `$argv[*]'.

       The  `:'  modifiers described under History substitution, except for `:p', can be applied to the sub-
       stitutions above.  More than one may be used.  (+) Braces may be needed to insulate a  variable  sub-
       stitution  from  a  literal colon just as with History substitution (q.v.); any modifiers must appear
       within the braces.

       The following substitutions can not be modified with `:' modifiers.

               Substitutes the string `1' if name is set, `0' if it is not.
       $?0     Substitutes `1' if the current input filename is known, `0' if it  is  not.   Always  `0'  in
               interactive shells.
               Substitutes the number of words in name.
       $#      Equivalent to `$#argv'.  (+)
               Substitutes the number of characters in name.  (+)
               Substitutes the number of characters in $argv[number].  (+)
       $?      Equivalent to `$status'.  (+)
       $$      Substitutes the (decimal) process number of the (parent) shell.
       $!      Substitutes  the  (decimal)  process  number  of  the last background process started by this
               shell.  (+)
       $_      Substitutes the command line of the last command executed.  (+)
       $<      Substitutes a line from the standard input, with no further  interpretation  thereafter.   It
               can  be used to read from the keyboard in a shell script.  (+) While csh always quotes $<, as
               if it were equivalent to `$<:q', tcsh does not.  Furthermore, when tcsh is waiting for a line
               to  be  typed the user may type an interrupt to interrupt the sequence into which the line is
               to be substituted, but csh does not allow this.

       The editor command expand-variables, normally bound to `^X-$', can be used  to  interactively  expand
       individual variables.

   Command, filename and directory stack substitution
       The remaining substitutions are applied selectively to the arguments of builtin commands.  This means
       that portions of expressions which are not evaluated are not subjected to these expansions.  For com-
       mands  which are not internal to the shell, the command name is substituted separately from the argu-
       ment list.  This occurs very late, after input-output redirection is performed, and in a child of the
       main shell.

   Command substitution
       Command  substitution  is  indicated by a command enclosed in ``'.  The output from such a command is
       broken into separate words at blanks, tabs and newlines, and null words are discarded.  The output is
       variable and command substituted and put in place of the original string.

       Command  substitutions  inside  double  quotes  (`"') retain blanks and tabs; only newlines force new
       words.  The single final newline does not force a new word in any case.  It is thus  possible  for  a
       command substitution to yield only part of a word, even if the command outputs a complete line.

       By  default,  the shell since version 6.12 replaces all newline and carriage return characters in the
       command by spaces.  If this is switched off by unsetting csubstnonl, newlines  separate  commands  as

   Filename substitution
       If  a word contains any of the characters `*', `?', `[' or `{' or begins with the character `~' it is
       a candidate for filename substitution, also known as ``globbing''.  This word is then regarded  as  a
       pattern (``glob-pattern''), and replaced with an alphabetically sorted list of file names which match
       the pattern.

       In matching filenames, the character `.' at the beginning of a filename or  immediately  following  a
       `/',  as  well as the character `/' must be matched explicitly.  The character `*' matches any string
       of characters, including the null string.  The character  `?'  matches  any  single  character.   The
       sequence  `[...]'  matches  any one of the characters enclosed.  Within `[...]', a pair of characters
       separated by `-' matches any character lexically between the two.

       (+) Some glob-patterns can be negated: The sequence `[^...]' matches any single character not  speci-
       fied by the characters and/or ranges of characters in the braces.

       An entire glob-pattern can also be negated with `^':

           > echo *
           bang crash crunch ouch
           > echo ^cr*
           bang ouch

       Glob-patterns  which  do  not  use `?', `*', or `[]' or which use `{}' or `~' (below) are not negated

       The metanotation `a{b,c,d}e' is a shorthand for `abe ace ade'.   Left-to-right  order  is  preserved:
       `/usr/source/s1/{oldls,ls}.c'  expands  to `/usr/source/s1/oldls.c /usr/source/s1/ls.c'.  The results
       of matches are sorted separately at a low level to preserve this order: `../{memo,*box}' might expand
       to  `../memo ../box ../mbox'.  (Note that `memo' was not sorted with the results of matching `*box'.)
       It is not an error when this construct expands to files which do not exist, but it is possible to get
       an  error  from  a command to which the expanded list is passed.  This construct may be nested.  As a
       special case the words `{', `}' and `{}' are passed undisturbed.

       The character `~' at the beginning of a filename refers to home directories.  Standing  alone,  i.e.,
       `~', it expands to the invoker's home directory as reflected in the value of the home shell variable.
       When followed by a name consisting of letters, digits and `-' characters the  shell  searches  for  a
       user  with that name and substitutes their home directory; thus `~ken' might expand to `/usr/ken' and
       `~ken/chmach' to `/usr/ken/chmach'.  If the character `~' is followed by a  character  other  than  a
       letter  or  `/' or appears elsewhere than at the beginning of a word, it is left undisturbed.  A com-
       mand like `setenv MANPATH /usr/man:/usr/local/man:~/lib/man' does not, therefore, do  home  directory
       substitution as one might hope.

       It  is an error for a glob-pattern containing `*', `?', `[' or `~', with or without `^', not to match
       any files.  However, only one pattern in a list of glob-patterns must match a file  (so  that,  e.g.,
       `rm  *.a  *.c  *.o'  would  fail only if there were no files in the current directory ending in `.a',
       `.c', or `.o'), and if the nonomatch shell variable is set a pattern  (or  list  of  patterns)  which
       matches nothing is left unchanged rather than causing an error.

       The  noglob  shell  variable  can be set to prevent filename substitution, and the expand-glob editor
       command, normally bound to `^X-*', can be used to interactively expand individual filename  substitu-

   Directory stack substitution (+)
       The  directory  stack  is a list of directories, numbered from zero, used by the pushd, popd and dirs
       builtin commands (q.v.).  dirs can print, store in a file, restore and clear the directory  stack  at
       any time, and the savedirs and dirsfile shell variables can be set to store the directory stack auto-
       matically on logout and restore it on login.  The dirstack shell variable can be examined to see  the
       directory stack and set to put arbitrary directories into the directory stack.

       The  character  `='  followed  by one or more digits expands to an entry in the directory stack.  The
       special case `=-' expands to the last directory in the stack.  For example,

           > dirs -v
           0       /usr/bin
           1       /usr/spool/uucp
           2       /usr/accts/sys
           > echo =1
           > echo =0/calendar
           > echo =-

       The noglob and nonomatch shell variables and the expand-glob editor command apply to directory  stack
       as well as filename substitutions.

   Other substitutions (+)
       There  are  several  more  transformations involving filenames, not strictly related to the above but
       mentioned here for completeness.  Any filename may be expanded to a full path when the symlinks vari-
       able  (q.v.) is set to `expand'.  Quoting prevents this expansion, and the normalize-path editor com-
       mand does it on demand.  The normalize-command editor command expands  commands  in  PATH  into  full
       paths on demand.  Finally, cd and pushd interpret `-' as the old working directory (equivalent to the
       shell variable owd).  This is not a substitution at all, but an abbreviation recognized by only those
       commands.  Nonetheless, it too can be prevented by quoting.

       The  next three sections describe how the shell executes commands and deals with their input and out-

   Simple commands, pipelines and sequences
       A simple command is a sequence of words, the first of which specifies the command to be executed.   A
       series of simple commands joined by `|' characters forms a pipeline.  The output of each command in a
       pipeline is connected to the input of the next.

       Simple commands and pipelines may be joined into sequences with `;', and  will  be  executed  sequen-
       tially.   Commands  and pipelines can also be joined into sequences with `||' or `&&', indicating, as
       in the C language, that the second is to be executed only if the  first  fails  or  succeeds  respec-

       A  simple command, pipeline or sequence may be placed in parentheses, `()', to form a simple command,
       which may in turn be a component of a pipeline or sequence.  A command, pipeline or sequence  can  be
       executed without waiting for it to terminate by following it with an `&'.

   Builtin and non-builtin command execution
       Builtin  commands are executed within the shell.  If any component of a pipeline except the last is a
       builtin command, the pipeline is executed in a subshell.

       Parenthesized commands are always executed in a subshell.

           (cd; pwd); pwd

       thus prints the home directory, leaving you where you were (printing this after the home  directory),

           cd; pwd

       leaves  you  in  the  home  directory.  Parenthesized commands are most often used to prevent cd from
       affecting the current shell.

       When a command to be executed is found not to be a builtin command the shell attempts to execute  the
       command via execve(2).  Each word in the variable path names a directory in which the shell will look
       for the command.  If it is given neither a -c nor a -t option, the shell hashes the  names  in  these
       directories  into  an internal table so that it will try an execve(2) in only a directory where there
       is a possibility that the command resides there.  This greatly speeds command location when  a  large
       number  of  directories  are  present in the search path.  If this mechanism has been turned off (via
       unhash), if the shell was given a -c or -t argument or in any case for each  directory  component  of
       path  which  does not begin with a `/', the shell concatenates the current working directory with the
       given command name to form a path name of a file which it then attempts to execute.

       If the file has execute permissions but is not an executable to the system (i.e., it  is  neither  an
       executable  binary nor a script that specifies its interpreter), then it is assumed to be a file con-
       taining shell commands and a new shell is spawned to read it.  The shell special alias may be set  to
       specify an interpreter other than the shell itself.

       On  systems  which do not understand the `#!' script interpreter convention the shell may be compiled
       to emulate it; see the version shell variable.  If so, the shell checks the first line of the file to
       see  if  it  is of the form `#!interpreter arg ...'.  If it is, the shell starts interpreter with the
       given args and feeds the file to it on standard input.

       The standard input and standard output of a command may be redirected with the following syntax:

       < name  Open file name (which is first variable, command  and  filename  expanded)  as  the  standard
       << word Read the shell input up to a line which is identical to word.  word is not subjected to vari-
               able, filename or command substitution, and each input line is compared to  word  before  any
               substitutions  are  done on this input line.  Unless a quoting `\', `"', `' or ``' appears in
               word variable and command substitution is performed on the intervening lines, allowing `\' to
               quote  `$',  `\' and ``'.  Commands which are substituted have all blanks, tabs, and newlines
               preserved, except for the final newline which is dropped.  The resultant text is placed in an
               anonymous temporary file which is given to the command as standard input.
       > name
       >! name
       >& name
       >&! name
               The  file name is used as standard output.  If the file does not exist then it is created; if
               the file exists, it is truncated, its previous contents being lost.

               If the shell variable noclobber is set, then the file must not exist or be a  character  spe-
               cial file (e.g., a terminal or `/dev/null') or an error results.  This helps prevent acciden-
               tal destruction of files.  In this case the `!' forms can be used to suppress this check.

               The forms involving `&' route the diagnostic output into the specified file as  well  as  the
               standard output.  name is expanded in the same way as `<' input filenames are.
       >> name
       >>& name
       >>! name
       >>&! name
               Like  `>',  but  appends  output to the end of name.  If the shell variable noclobber is set,
               then it is an error for the file not to exist, unless one of the `!' forms is given.

       A command receives the environment in which the shell was invoked as  modified  by  the  input-output
       parameters  and  the  presence of the command in a pipeline.  Thus, unlike some previous shells, com-
       mands run from a file of shell commands have no access to the text of the commands by default; rather
       they  receive the original standard input of the shell.  The `<<' mechanism should be used to present
       inline data.  This permits shell command scripts to function as components of  pipelines  and  allows
       the  shell  to block read its input.  Note that the default standard input for a command run detached
       is not the empty file /dev/null, but the original standard input of the shell.  If this is a terminal
       and  if the process attempts to read from the terminal, then the process will block and the user will
       be notified (see Jobs).

       Diagnostic output may be directed through a pipe with the standard output.  Simply use the form  `|&'
       rather than just `|'.

       The  shell  cannot presently redirect diagnostic output without also redirecting standard output, but
       `(command > output-file) >& error-file' is often an acceptable  workaround.   Either  output-file  or
       error-file may be `/dev/tty' to send output to the terminal.

       Having  described  how the shell accepts, parses and executes command lines, we now turn to a variety
       of its useful features.

   Control flow
       The shell contains a number of commands which can be used to regulate the flow of control in  command
       files (shell scripts) and (in limited but useful ways) from terminal input.  These commands all oper-
       ate by forcing the shell to reread or skip in its input and, due to the implementation, restrict  the
       placement of some of the commands.

       The  foreach,  switch,  and  while  statements, as well as the if-then-else form of the if statement,
       require that the major keywords appear in a single simple command on an input line as shown below.

       If the shell's input is not seekable, the shell buffers up input whenever a loop is  being  read  and
       performs  seeks  in  this  internal  buffer to accomplish the rereading implied by the loop.  (To the
       extent that this allows, backward gotos will succeed on non-seekable inputs.)

       The if, while and exit builtin commands use expressions with a common syntax.   The  expressions  can
       include  any  of the operators described in the next three sections.  Note that the @ builtin command
       (q.v.) has its own separate syntax.

   Logical, arithmetical and comparison operators
       These operators are similar to those of C and have the same precedence.  They include

           ||  &&  |  ^  &  ==  !=  =~  !~  <=  >=
           <  > <<  >>  +  -  *  /  %  !  ~  (  )

       Here the precedence increases to the right, `==' `!=' `=~' and `!~', `<=' `>=' `<' and `>', `<<'  and
       `>>',  `+' and `-', `*' `/' and `%' being, in groups, at the same level.  The `==' `!=' `=~' and `!~'
       operators compare their arguments as strings; all others operate on numbers.  The operators `=~'  and
       `!~' are like `!=' and `==' except that the right hand side is a glob-pattern (see Filename substitu-
       tion) against which the left hand operand is matched.  This reduces the need for use  of  the  switch
       builtin command in shell scripts when all that is really needed is pattern matching.

       Strings  which begin with `0' are considered octal numbers.  Null or missing arguments are considered
       `0'.  The results of all expressions are strings, which represent decimal numbers.  It  is  important
       to  note that no two components of an expression can appear in the same word; except when adjacent to
       components of expressions which are syntactically significant to the parser (`&' `|' `<' `>' `(' `)')
       they should be surrounded by spaces.

   Command exit status
       Commands  can  be  executed in expressions and their exit status returned by enclosing them in braces
       (`{}').  Remember that the braces should be separated from the words of the command by spaces.   Com-
       mand  executions  succeed,  returning  true, i.e., `1', if the command exits with status 0, otherwise
       they fail, returning false, i.e., `0'.  If more detailed status information is required then the com-
       mand should be executed outside of an expression and the status shell variable examined.

   File inquiry operators
       Some  of these operators perform true/false tests on files and related objects.  They are of the form
       -op file, where op is one of

           r   Read access
           w   Write access
           x   Execute access
           X   Executable in the path or shell builtin, e.g., `-X ls' and `-X ls-F' are generally true,  but
               `-X /bin/ls' is not (+)
           e   Existence
           o   Ownership
           z   Zero size
           s   Non-zero size (+)
           f   Plain file
           d   Directory
           l   Symbolic link (+) *
           b   Block special file (+)
           c   Character special file (+)
           p   Named pipe (fifo) (+) *
           S   Socket special file (+) *
           u   Set-user-ID bit is set (+)
           g   Set-group-ID bit is set (+)
           k   Sticky bit is set (+)
           t   file (which must be a digit) is an open file descriptor for a terminal device (+)
           R   Has been migrated (convex only) (+)
           L   Applies  subsequent  operators  in a multiple-operator test to a symbolic link rather than to
               the file to which the link points (+) *

       file is command and filename expanded and then tested to see if it has the specified relationship  to
       the  real user.  If file does not exist or is inaccessible or, for the operators indicated by `*', if
       the specified file type does not exist on the current system, then all enquiries return false,  i.e.,

       These  operators  may  be combined for conciseness: `-xy file' is equivalent to `-x file && -y file'.
       (+) For example, `-fx' is true (returns `1') for plain executable files, but not for directories.

       L may be used in a multiple-operator test to apply subsequent operators to  a  symbolic  link  rather
       than to the file to which the link points.  For example, `-lLo' is true for links owned by the invok-
       ing user.  Lr, Lw and Lx are always true for links and false for non-links.  L has a different  mean-
       ing when it is the last operator in a multiple-operator test; see below.

       It is possible but not useful, and sometimes misleading, to combine operators which expect file to be
       a file with operators which do not, (e.g., X and t).  Following L with a non-file operator  can  lead
       to particularly strange results.

       Other  operators  return other information, i.e., not just `0' or `1'.  (+) They have the same format
       as before; op may be one of

           A       Last file access time, as the number of seconds since the epoch
           A:      Like A, but in timestamp format, e.g., `Fri May 14 16:36:10 1993'
           M       Last file modification time
           M:      Like M, but in timestamp format
           C       Last inode modification time
           C:      Like C, but in timestamp format
           D       Device number
           I       Inode number
           F       Composite file identifier, in the form device:inode
           L       The name of the file pointed to by a symbolic link
           N       Number of (hard) links
           P       Permissions, in octal, without leading zero
           P:      Like P, with leading zero
           Pmode   Equivalent to `-P file & mode', e.g., `-P22 file' returns `22' if  file  is  writable  by
                   group and other, `20' if by group only, and `0' if by neither
           Pmode:  Like Pmode:, with leading zero
           U       Numeric userid
           U:      Username, or the numeric userid if the username is unknown
           G       Numeric groupid
           G:      Groupname, or the numeric groupid if the groupname is unknown
           Z       Size, in bytes

       Only  one  of  these operators may appear in a multiple-operator test, and it must be the last.  Note
       that L has a different meaning at the end of and elsewhere in a multiple-operator test.  Because  `0'
       is  a  valid  return  value  for many of these operators, they do not return `0' when they fail: most
       return `-1', and F returns `:'.

       If the shell is compiled with POSIX defined (see the version shell variable), the result  of  a  file
       inquiry  is  based  on  the permission bits of the file and not on the result of the access(2) system
       call.  For example, if one tests a file with -w whose permissions would ordinarily allow writing  but
       which  is  on  a  file system mounted read-only, the test will succeed in a POSIX shell but fail in a
       non-POSIX shell.

       File inquiry operators can also be evaluated with the filetest builtin command (q.v.) (+).

       The shell associates a job with each pipeline.  It keeps a table of current jobs, printed by the jobs
       command,  and assigns them small integer numbers.  When a job is started asynchronously with `&', the
       shell prints a line which looks like

           [1] 1234

       indicating that the job which was started asynchronously was job number 1  and  had  one  (top-level)
       process, whose process id was 1234.

       If  you  are  running a job and wish to do something else you may hit the suspend key (usually `^Z'),
       which sends a STOP signal to the current job.  The shell will then normally indicate that the job has
       been  `Suspended'  and print another prompt.  If the listjobs shell variable is set, all jobs will be
       listed like the jobs builtin command; if it is set to `long' the listing will be in long format, like
       `jobs  -l'.   You  can then manipulate the state of the suspended job.  You can put it in the ``back-
       ground'' with the bg command or run some other commands and eventually bring the job  back  into  the
       ``foreground''  with  fg.   (See also the run-fg-editor editor command.)  A `^Z' takes effect immedi-
       ately and is like an interrupt in that pending output and unread  input  are  discarded  when  it  is
       typed.  The wait builtin command causes the shell to wait for all background jobs to complete.

       The  `^]'  key  sends a delayed suspend signal, which does not generate a STOP signal until a program
       attempts to read(2) it, to the current job.  This can usefully be typed ahead when you have  prepared
       some  commands  for  a job which you wish to stop after it has read them.  The `^Y' key performs this
       function in csh(1); in tcsh, `^Y' is an editing command.  (+)

       A job being run in the background stops if it tries to read from the terminal.  Background  jobs  are
       normally allowed to produce output, but this can be disabled by giving the command `stty tostop'.  If
       you set this tty option, then background jobs will stop when they try to produce output like they  do
       when they try to read input.

       There  are  several ways to refer to jobs in the shell.  The character `%' introduces a job name.  If
       you wish to refer to job number 1, you can name it as `%1'.  Just naming a job brings it to the fore-
       ground; thus `%1' is a synonym for `fg %1', bringing job 1 back into the foreground.  Similarly, say-
       ing `%1 &' resumes job 1 in the background, just like `bg %1'.  A job can also be named by  an  unam-
       biguous  prefix  of  the  string typed in to start it: `%ex' would normally restart a suspended ex(1)
       job, if there were only one suspended job whose name began with the string `ex'.  It is also possible
       to say `%?string' to specify a job whose text contains string, if there is only one such job.

       The  shell  maintains  a  notion of the current and previous jobs.  In output pertaining to jobs, the
       current job is marked with a `+' and the previous job with a `-'.  The abbreviations `%+',  `%',  and
       (by  analogy  with  the  syntax of the history mechanism) `%%' all refer to the current job, and `%-'
       refers to the previous job.

       The job control mechanism requires that the stty(1) option `new' be set on some systems.   It  is  an
       artifact  from  a `new' implementation of the tty driver which allows generation of interrupt charac-
       ters from the keyboard to tell jobs to stop.  See stty(1) and the setty builtin command  for  details
       on setting options in the new tty driver.

   Status reporting
       The  shell  learns  immediately whenever a process changes state.  It normally informs you whenever a
       job becomes blocked so that no further progress is possible,  but  only  right  before  it  prints  a
       prompt.   This  is  done  so  that it does not otherwise disturb your work.  If, however, you set the
       shell variable notify, the shell will notify you immediately of changes of status in background jobs.
       There  is also a shell command notify which marks a single process so that its status changes will be
       immediately reported.  By default notify marks the current process; simply say `notify' after  start-
       ing a background job to mark it.

       When  you  try  to  leave the shell while jobs are stopped, you will be warned that `You have stopped
       jobs.' You may use the jobs command to see what they are.  If you do this or immediately try to  exit
       again, the shell will not warn you a second time, and the suspended jobs will be terminated.

   Automatic, periodic and timed events (+)
       There  are  various ways to run commands and take other actions automatically at various times in the
       ``life cycle'' of the shell.  They are summarized here, and described in detail under the appropriate
       Builtin commands, Special shell variables and Special aliases.

       The  sched  builtin command puts commands in a scheduled-event list, to be executed by the shell at a
       given time.

       The beepcmd, cwdcmd, periodic, precmd, postcmd, and jobcmd Special aliases can be set,  respectively,
       to  execute commands when the shell wants to ring the bell, when the working directory changes, every
       tperiod minutes, before each prompt, before each command gets executed, after each command gets  exe-
       cuted, and when a job is started or is brought into the foreground.

       The autologout shell variable can be set to log out or lock the shell after a given number of minutes
       of inactivity.

       The mail shell variable can be set to check for new mail periodically.

       The printexitvalue shell variable can be set to print the exit status of commands which exit  with  a
       status other than zero.

       The  rmstar  shell  variable can be set to ask the user, when `rm *' is typed, if that is really what
       was meant.

       The time shell variable can be set to execute the time builtin command after the  completion  of  any
       process that takes more than a given number of CPU seconds.

       The watch and who shell variables can be set to report when selected users log in or out, and the log
       builtin command reports on those users at any time.

   Native Language System support (+)
       The shell is eight bit clean (if so compiled; see the version shell variable) and thus supports char-
       acter  sets  needing  this capability.  NLS support differs depending on whether or not the shell was
       compiled to use the system's NLS (again, see version).  In either case, 7-bit ASCII  is  the  default
       character code (e.g., the classification of which characters are printable) and sorting, and changing
       the LANG or LC_CTYPE environment variables causes a check for possible changes in these respects.

       When using the system's NLS, the setlocale(3) function is called to determine  appropriate  character
       code/classification  and  sorting  (e.g.,  a  'en_CA.UTF-8' would yield "UTF-8" as a character code).
       This function typically examines the LANG and LC_CTYPE environment variables;  refer  to  the  system
       documentation for further details.  When not using the system's NLS, the shell simulates it by assum-
       ing that the ISO 8859-1 character set is used whenever either of the LANG and LC_CTYPE variables  are
       set, regardless of their values.  Sorting is not affected for the simulated NLS.

       In addition, with both real and simulated NLS, all printable characters in the range \200-\377, i.e.,
       those that have M-char bindings, are automatically rebound to self-insert-command.  The corresponding
       binding for the escape-char sequence, if any, is left alone.  These characters are not rebound if the
       NOREBIND environment variable is set.  This may be useful for the simulated NLS or a  primitive  real
       NLS  which assumes full ISO 8859-1.  Otherwise, all M-char bindings in the range \240-\377 are effec-
       tively undone.  Explicitly rebinding the relevant keys with bindkey is of course still possible.

       Unknown characters (i.e., those that are neither printable nor control characters) are printed in the
       format  \nnn.  If the tty is not in 8 bit mode, other 8 bit characters are printed by converting them
       to ASCII and using standout mode.  The shell never changes the 7/8 bit mode of  the  tty  and  tracks
       user-initiated changes of 7/8 bit mode.  NLS users (or, for that matter, those who want to use a meta
       key) may need to explicitly set the tty in 8 bit mode through the  appropriate  stty(1)  command  in,
       e.g., the ~/.login file.

   OS variant support (+)
       A  number  of  new builtin commands are provided to support features in particular operating systems.
       All are described in detail in the Builtin commands section.

       On systems that support TCF (aix-ibm370, aix-ps2), getspath and setspath get and set the system  exe-
       cution  path,  getxvers and setxvers get and set the experimental version prefix and migrate migrates
       processes between sites.  The jobs builtin prints the site on which each job is executing.

       Under BS2000, bs2cmd executes commands of the underlying BS2000/OSD operating system.

       Under Domain/OS, inlib adds shared libraries to the current environment, rootnode changes the  rootn-
       ode and ver changes the systype.

       Under Mach, setpath is equivalent to Mach's setpath(1).

       Under Masscomp/RTU and Harris CX/UX, universe sets the universe.

       Under Harris CX/UX, ucb or att runs a command under the specified universe.

       Under Convex/OS, warp prints or sets the universe.

       The  VENDOR,  OSTYPE  and  MACHTYPE environment variables indicate respectively the vendor, operating
       system and machine type (microprocessor class or machine model) of the  system  on  which  the  shell
       thinks  it  is running.  These are particularly useful when sharing one's home directory between sev-
       eral types of machines; one can, for example,

           set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)

       in one's ~/.login and put executables compiled for each machine in the appropriate directory.

       The version shell variable indicates what options were chosen when the shell was compiled.

       Note also the newgrp builtin, the afsuser and echo_style shell  variables  and  the  system-dependent
       locations of the shell's input files (see FILES).

   Signal handling
       Login  shells  ignore  interrupts  when  reading  the file ~/.logout.  The shell ignores quit signals
       unless started with -q.  Login shells catch the terminate signal, but non-login  shells  inherit  the
       terminate  behavior from their parents.  Other signals have the values which the shell inherited from
       its parent.

       In shell scripts, the shell's handling of interrupt and terminate  signals  can  be  controlled  with
       onintr, and its handling of hangups can be controlled with hup and nohup.

       The  shell  exits on a hangup (see also the logout shell variable).  By default, the shell's children
       do too, but the shell does not send them a hangup when it exits.  hup arranges for the shell to  send
       a hangup to a child when it exits, and nohup sets a child to ignore hangups.

   Terminal management (+)
       The  shell uses three different sets of terminal (``tty'') modes: `edit', used when editing, `quote',
       used when quoting literal characters, and `execute', used when executing commands.  The  shell  holds
       some  settings  in  each  mode  constant,  so commands which leave the tty in a confused state do not
       interfere with the shell.  The shell also matches changes in the speed and padding of the  tty.   The
       list  of  tty modes that are kept constant can be examined and modified with the setty builtin.  Note
       that although the editor uses CBREAK mode (or its equivalent), it takes typed-ahead  characters  any-

       The  echotc, settc and telltc commands can be used to manipulate and debug terminal capabilities from
       the command line.

       On systems that support SIGWINCH or SIGWINDOW, the shell adapts to window resizing automatically  and
       adjusts the environment variables LINES and COLUMNS if set.  If the environment variable TERMCAP con-
       tains li# and co# fields, the shell adjusts them to reflect the new window size.

       The next sections of this manual describe all of the available Builtin commands, Special aliases  and
       Special shell variables.

   Builtin commands
       %job    A synonym for the fg builtin command.

       %job &  A synonym for the bg builtin command.

       :       Does nothing, successfully.

       @ name = expr
       @ name[index] = expr
       @ name++|--
       @ name[index]++|--
               The first form prints the values of all shell variables.

               The  second form assigns the value of expr to name.  The third form assigns the value of expr
               to the index'th component of name; both name and its index'th component must already exist.

               expr may contain the operators `*', `+', etc., as in C.  If expr contains `<', `>', `&' or `'
               then at least that part of expr must be placed within `()'.  Note that the syntax of expr has
               nothing to do with that described under Expressions.

               The fourth and fifth forms increment (`++') or decrement (`--') name or its  index'th  compo-

               The  space between `@' and name is required.  The spaces between name and `=' and between `='
               and expr are optional.  Components of expr must be separated by spaces.

       alias [name [wordlist]]
               Without arguments, prints all aliases.  With name, prints the alias for name.  With name  and
               wordlist,  assigns  wordlist  as the alias of name.  wordlist is command and filename substi-
               tuted.  name may not be `alias' or `unalias'.  See also the unalias builtin command.

       alloc   Shows the amount of dynamic memory acquired, broken down into used and free memory.  With  an
               argument  shows  the  number  of  free and used blocks in each size category.  The categories
               start at size 8 and double at each step.  This command's output may vary across system types,
               because systems other than the VAX may use a different memory allocator.

       bg [%job ...]
               Puts the specified jobs (or, without arguments, the current job) into the background, contin-
               uing each if it is stopped.  job may be a number, a string, `', `%', `+' or `-' as  described
               under Jobs.

       bindkey [-l|-d|-e|-v|-u] (+)
       bindkey [-a] [-b] [-k] [-r] [--] key (+)
       bindkey [-a] [-b] [-k] [-c|-s] [--] key command (+)
               Without  options, the first form lists all bound keys and the editor command to which each is
               bound, the second form lists the editor command to which key is  bound  and  the  third  form
               binds the editor command command to key.  Options include:

               -l  Lists all editor commands and a short description of each.
               -d  Binds all keys to the standard bindings for the default editor.
               -e  Binds all keys to the standard GNU Emacs-like bindings.
               -v  Binds all keys to the standard vi(1)-like bindings.
               -a  Lists or changes key-bindings in the alternative key map.  This is the key map used in vi
                   command mode.
               -b  key is interpreted as a control character written ^character (e.g., `^A') or  C-character
                   (e.g., `C-A'), a meta character written M-character (e.g., `M-A'), a function key written
                   F-string (e.g., `F-string'), or an extended prefix key written X-character (e.g., `X-A').
               -k  key is interpreted as a symbolic arrow key name, which may be one of `down', `up', `left'
                   or `right'.
               -r  Removes key's binding.  Be careful: `bindkey -r' does not bind key to self-insert-command
                   (q.v.), it unbinds key completely.
               -c  command is interpreted as a builtin or external command instead of an editor command.
               -s  command  is  taken  as  a literal string and treated as terminal input when key is typed.
                   Bound keys in command are themselves reinterpreted, and this continues for ten levels  of
               --  Forces a break from option processing, so the next word is taken as key even if it begins
                   with '-'.
               -u (or any invalid option)
                   Prints a usage message.

               key may be a single character or a string.  If a command is bound  to  a  string,  the  first
               character  of  the  string is bound to sequence-lead-in and the entire string is bound to the

               Control characters in key can be literal (they can be typed by preceding them with the editor
               command  quoted-insert, normally bound to `^V') or written caret-character style, e.g., `^A'.
               Delete is written `^?'  (caret-question mark).   key  and  command  can  contain  backslashed
               escape sequences (in the style of System V echo(1)) as follows:

                   \a      Bell
                   \b      Backspace
                   \e      Escape
                   \f      Form feed
                   \n      Newline
                   \r      Carriage return
                   \t      Horizontal tab
                   \v      Vertical tab
                   \nnn    The ASCII character corresponding to the octal number nnn

               `\'  nullifies the special meaning of the following character, if it has any, notably `\' and

       bs2cmd bs2000-command (+)
               Passes bs2000-command to the BS2000 command interpreter for execution.  Only  non-interactive
               commands  can  be  executed, and it is not possible to execute any command that would overlay
               the image of the current process, like /EXECUTE or /CALL-PROCEDURE. (BS2000 only)

       break   Causes execution to resume after the end of the nearest  enclosing  foreach  or  while.   The
               remaining commands on the current line are executed.  Multi-level breaks are thus possible by
               writing them all on one line.

       breaksw Causes a break from a switch, resuming after the endsw.

       builtins (+)
               Prints the names of all builtin commands.

       bye (+) A synonym for the logout builtin command.  Available only if the shell was so  compiled;  see
               the version shell variable.

       case label:
               A label in a switch statement as discussed below.

       cd [-p] [-l] [-n|-v] [name]
               If a directory name is given, changes the shell's working directory to name.  If not, changes
               to home.  If name is `-' it is interpreted as the previous working directory (see Other  sub-
               stitutions).   (+) If name is not a subdirectory of the current directory (and does not begin
               with `/', `./' or `../'), each component of the variable cdpath is checked to see if it has a
               subdirectory  name.   Finally,  if  all  else  fails but name is a shell variable whose value
               begins with `/', then this is tried to see if it is a directory.

               With -p, prints the final directory stack, just like dirs.  The -l, -n and -v flags have  the
               same effect on cd as on dirs, and they imply -p.  (+)

               See also the implicitcd shell variable.

       chdir   A synonym for the cd builtin command.

       complete [command [word/pattern/list[:select]/[[suffix]/] ...]] (+)
               Without arguments, lists all completions.  With command, lists completions for command.  With
               command and word etc., defines completions.

               command may be a full command name or a glob-pattern (see  Filename  substitution).   It  can
               begin with `-' to indicate that completion should be used only when command is ambiguous.

               word  specifies which word relative to the current word is to be completed, and may be one of
               the following:

                   c   Current-word completion.  pattern is a glob-pattern which must match the beginning of
                       the current word on the command line.  pattern is ignored when completing the current
                   C   Like c, but includes pattern when completing the current word.
                   n   Next-word completion.  pattern is a glob-pattern which must match  the  beginning  of
                       the previous word on the command line.
                   N   Like n, but must match the beginning of the word two before the current word.
                   p   Position-dependent completion.  pattern is a numeric range, with the same syntax used
                       to index shell variables, which must include the current word.

               list, the list of possible completions, may be one of the following:

                   a       Aliases
                   b       Bindings (editor commands)
                   c       Commands (builtin or external commands)
                   C       External commands which begin with the supplied path prefix
                   d       Directories
                   D       Directories which begin with the supplied path prefix
                   e       Environment variables
                   f       Filenames
                   F       Filenames which begin with the supplied path prefix
                   g       Groupnames
                   j       Jobs
                   l       Limits
                   n       Nothing
                   s       Shell variables
                   S       Signals
                   t       Plain (``text'') files
                   T       Plain (``text'') files which begin with the supplied path prefix
                   v       Any variables
                   u       Usernames
                   x       Like n, but prints select when list-choices is used.
                   X       Completions
                   $var    Words from the variable var
                   (...)   Words from the given list
                   `...`   Words from the output of command

               select is an optional glob-pattern.  If given, words from only list  that  match  select  are
               considered and the fignore shell variable is ignored.  The last three types of completion may
               not have a select pattern, and x uses select as an explanatory message when the  list-choices
               editor command is used.

               suffix  is a single character to be appended to a successful completion.  If null, no charac-
               ter is appended.  If omitted (in which case the fourth delimiter  can  also  be  omitted),  a
               slash is appended to directories and a space to other words.

               Now for some examples.  Some commands take only directories as arguments, so there's no point
               completing plain files.

                   > complete cd 'p/1/d/'

               completes only the first word following `cd' (`p/1') with a directory.  p-type completion can
               also be used to narrow down command completion:

                   > co[^D]
                   complete compress
                   > complete -co* 'p/0/(compress)/'
                   > co[^D]
                   > compress

               This  completion  completes commands (words in position 0, `p/0') which begin with `co' (thus
               matching `co*') to `compress' (the only word in the list).  The leading  `-'  indicates  that
               this completion is to be used with only ambiguous commands.

                   > complete find 'n/-user/u/'

               is  an  example  of  n-type  completion.  Any word following `find' and immediately following
               `-user' is completed from the list of users.

                   > complete cc 'c/-I/d/'

               demonstrates c-type completion.  Any word following `cc' and beginning with `-I' is completed
               as a directory.  `-I' is not taken as part of the directory because we used lowercase c.

               Different lists are useful with different commands.

                   > complete alias 'p/1/a/'
                   > complete man 'p/*/c/'
                   > complete set 'p/1/s/'
                   > complete true 'p/1/x:Truth has no options./'

               These  complete  words  following  `alias'  with aliases, `man' with commands, and `set' with
               shell variables.  `true' doesn't have any options, so  x  does  nothing  when  completion  is
               attempted and prints `Truth has no options.' when completion choices are listed.

               Note  that  the  man  example, and several other examples below, could just as well have used
               'c/*' or 'n/*' as 'p/*'.

               Words can be completed from a variable evaluated at completion time,

                   > complete ftp 'p/1/$hostnames/'
                   > set hostnames = (
                   > ftp [^D]
                   > ftp [^C]
                   > set hostnames = (
                   > ftp [^D]

               or from a command run at completion time:

                   > complete kill 'p/*/`ps | awk \{print\ \$1\}`/'
                   > kill -9 [^D]
                   23113 23377 23380 23406 23429 23529 23530 PID

               Note that the complete command does not itself quote its arguments, so the braces, space  and
               `$' in `{print $1}' must be quoted explicitly.

               One command can have multiple completions:

                   > complete dbx 'p/2/(core)/' 'p/*/c/'

               completes the second argument to `dbx' with the word `core' and all other arguments with com-
               mands.  Note that the positional completion is specified  before  the  next-word  completion.
               Because completions are evaluated from left to right, if the next-word completion were speci-
               fied first it would always match and the positional completion would never be executed.  This
               is a common mistake when defining a completion.

               The  select  pattern is useful when a command takes files with only particular forms as argu-
               ments.  For example,

                   > complete cc 'p/*/f:*.[cao]/'

               completes `cc' arguments to files ending in only  `.c',  `.a',  or  `.o'.   select  can  also
               exclude  files,  using  negation  of a glob-pattern as described under Filename substitution.
               One might use

                   > complete rm 'p/*/f:^*.{c,h,cc,C,tex,1,man,l,y}/'

               to exclude precious source code from `rm'  completion.   Of  course,  one  could  still  type
               excluded  names  manually or override the completion mechanism using the complete-word-raw or
               list-choices-raw editor commands (q.v.).

               The `C', `D', `F' and `T' lists are like `c', `d', `f' and `t' respectively, but they use the
               select argument in a different way: to restrict completion to files beginning with a particu-
               lar path prefix.  For example, the Elm mail program uses `=' as  an  abbreviation  for  one's
               mail directory.  One might use

                   > complete elm c@=@F:$HOME/Mail/@

               to  complete `elm -f =' as if it were `elm -f ~/Mail/'.  Note that we used `@' instead of `/'
               to avoid confusion with the select argument, and we used `$HOME' instead of `~' because  home
               directory substitution works at only the beginning of a word.

               suffix  is  used  to add a nonstandard suffix (not space or `/' for directories) to completed

                   > complete finger 'c/*@/$hostnames/' 'p/1/u/@'

               completes arguments to `finger' from the list of users, appends an `@',  and  then  completes
               after  the  `@' from the `hostnames' variable.  Note again the order in which the completions
               are specified.

               Finally, here's a complex example for inspiration:

                   > complete find \
                   'n/-name/f/' 'n/-newer/f/' 'n/-{,n}cpio/f/' \
                   'n/-exec/c/' 'n/-ok/c/' 'n/-user/u/' \
                   'n/-group/g/' 'n/-fstype/(nfs 4.2)/' \
                   'n/-type/(b c d f l p s)/' \
                   'c/-/(name newer cpio ncpio exec ok user \
                   group fstype type atime ctime depth inum \
                   ls mtime nogroup nouser perm print prune \
                   size xdev)/' \

               This completes words following `-name', `-newer', `-cpio' or `ncpio' (note the pattern  which
               matches  both) to files, words following `-exec' or `-ok' to commands, words following `user'
               and `group' to users and groups respectively and words following `-fstype' or `-type' to mem-
               bers of the given lists.  It also completes the switches themselves from the given list (note
               the use of c-type completion) and completes anything not otherwise completed to a  directory.

               Remember  that programmed completions are ignored if the word being completed is a tilde sub-
               stitution (beginning with `~') or a variable (beginning with `$').  complete is an experimen-
               tal  feature, and the syntax may change in future versions of the shell.  See also the uncom-
               plete builtin command.

               Continues execution of the nearest enclosing while or foreach.  The rest of the  commands  on
               the current line are executed.

               Labels the default case in a switch statement.  It should come after all case labels.

       dirs [-l] [-n|-v]
       dirs -S|-L [filename] (+)
       dirs -c (+)
               The first form prints the directory stack.  The top of the stack is at the left and the first
               directory in the stack is the current directory.  With -l, `~' or `~name' in  the  output  is
               expanded  explicitly  to  home or the pathname of the home directory for user name.  (+) With
               -n, entries are wrapped before they reach the edge of the screen.  (+) With -v,  entries  are
               printed one per line, preceded by their stack positions.  (+) If more than one of -n or -v is
               given, -v takes precedence.  -p is accepted but does nothing.

               With -S, the second form saves the directory stack to filename as a series of  cd  and  pushd
               commands.   With  -L,  the shell sources filename, which is presumably a directory stack file
               saved by the -S option or the savedirs mechanism.  In either case, dirsfile is used if  file-
               name is not given and ~/.cshdirs is used if dirsfile is unset.

               Note  that  login  shells  do the equivalent of `dirs -L' on startup and, if savedirs is set,
               `dirs -S' before exiting.  Because only ~/.tcshrc  is  normally  sourced  before  ~/.cshdirs,
               dirsfile should be set in ~/.tcshrc rather than ~/.login.

               The last form clears the directory stack.

       echo [-n] word ...
               Writes  each  word  to the shell's standard output, separated by spaces and terminated with a
               newline.  The echo_style shell variable may be set to emulate (or not) the flags  and  escape
               sequences of the BSD and/or System V versions of echo; see echo(1).

       echotc [-sv] arg ... (+)
               Exercises  the  terminal  capabilities  (see termcap(5)) in args.  For example, 'echotc home'
               sends the cursor to the home position, 'echotc cm 3 10' sends it to column 3 and row 10,  and
               'echotc  ts  0;  echo  "This  is a test."; echotc fs' prints "This is a test."  in the status

               If arg is 'baud', 'cols', 'lines', 'meta' or 'tabs', prints  the  value  of  that  capability
               ("yes"  or  "no"  indicating  that  the terminal does or does not have that capability).  One
               might use this to make the output from a shell script less  verbose  on  slow  terminals,  or
               limit command output to the number of lines on the screen:

                   > set history=`echotc lines`
                   > @ history--

               Termcap  strings  may contain wildcards which will not echo correctly.  One should use double
               quotes when setting a shell variable to a terminal capability string,  as  in  the  following
               example that places the date in the status line:

                   > set tosl="`echotc ts 0`"
                   > set frsl="`echotc fs`"
                   > echo -n "$tosl";date; echo -n "$frsl"

               With -s, nonexistent capabilities return the empty string rather than causing an error.  With
               -v, messages are verbose.

       endsw   See the description of the foreach, if, switch, and while statements below.

       eval arg ...
               Treats the arguments as input to the shell and executes the resulting command(s) in the  con-
               text  of the current shell.  This is usually used to execute commands generated as the result
               of command or variable substitution, because parsing occurs before these substitutions.   See
               tset(1) for a sample use of eval.

       exec command
               Executes the specified command in place of the current shell.

       exit [expr]
               The  shell  exits  either  with  the value of the specified expr (an expression, as described
               under Expressions) or, without expr, with the value of the status variable.

       fg [%job ...]
               Brings the specified jobs (or, without arguments, the current job) into the foreground,  con-
               tinuing  each  if  it  is  stopped.   job  may  be a number, a string, `', `%', `+' or `-' as
               described under Jobs.  See also the run-fg-editor editor command.

       filetest -op file ... (+)
               Applies op (which is a file inquiry operator as described under File  inquiry  operators)  to
               each file and returns the results as a space-separated list.

       foreach name (wordlist)
       end     Successively  sets  the variable name to each member of wordlist and executes the sequence of
               commands between this command and the matching end.  (Both foreach and end must appear  alone
               on  separate  lines.)   The  builtin command continue may be used to continue the loop prema-
               turely and the builtin command break to terminate it prematurely.  When this command is  read
               from  the  terminal, the loop is read once prompting with `foreach? ' (or prompt2) before any
               statements in the loop are executed.  If you make a mistake typing in a loop at the  terminal
               you can rub it out.

       getspath (+)
               Prints the system execution path.  (TCF only)

       getxvers (+)
               Prints the experimental version prefix.  (TCF only)

       glob wordlist
               Like  echo,  but  no `\' escapes are recognized and words are delimited by null characters in
               the output.  Useful for programs which wish to use the shell to filename  expand  a  list  of

       goto word
               word  is  filename  and command-substituted to yield a string of the form `label'.  The shell
               rewinds its input as much as possible, searches for a line of  the  form  `label:',  possibly
               preceded by blanks or tabs, and continues execution after that line.

               Prints  a statistics line indicating how effective the internal hash table has been at locat-
               ing commands (and avoiding exec's).  An exec is attempted for  each  component  of  the  path
               where  the hash function indicates a possible hit, and in each component which does not begin
               with a `/'.

               On machines without vfork(2), prints only the number and size of hash buckets.

       history [-hTr] [n]
       history -S|-L|-M [filename] (+)
       history -c (+)
               The first form prints the history event list.  If n is given only the n  most  recent  events
               are  printed  or saved.  With -h, the history list is printed without leading numbers.  If -T
               is specified, timestamps are printed also in comment form.  (This  can  be  used  to  produce
               files suitable for loading with 'history -L' or 'source -h'.)  With -r, the order of printing
               is most recent first rather than oldest first.

               With -S, the second form saves the history list to filename.  If the first word of the  save-
               hist  shell  variable  is  set to a number, at most that many lines are saved.  If the second
               word of savehist is set to `merge', the history list is merged with the existing history file
               instead  of replacing it (if there is one) and sorted by time stamp.  (+) Merging is intended
               for an environment like the X Window System with several shells in  simultaneous  use.   Cur-
               rently it succeeds only when the shells quit nicely one after another.

               With  -L,  the  shell  appends  filename,  which is presumably a history list saved by the -S
               option or the savehist mechanism, to the history list.  -M is like -L, but  the  contents  of
               filename  are merged into the history list and sorted by timestamp.  In either case, histfile
               is used if filename is not given and ~/.history is used if histfile is unset.   `history  -L'
               is exactly like 'source -h' except that it does not require a filename.

               Note  that login shells do the equivalent of `history -L' on startup and, if savehist is set,
               `history -S' before exiting.  Because only ~/.tcshrc is normally sourced  before  ~/.history,
               histfile should be set in ~/.tcshrc rather than ~/.login.

               If histlit is set, the first and second forms print and save the literal (unexpanded) form of
               the history list.

               The last form clears the history list.

       hup [command] (+)
               With command, runs command such that it will exit on a hangup signal  and  arranges  for  the
               shell  to send it a hangup signal when the shell exits.  Note that commands may set their own
               response to hangups, overriding hup.  Without an argument (allowed in only a  shell  script),
               causes  the  shell to exit on a hangup for the remainder of the script.  See also Signal han-
               dling and the nohup builtin command.

       if (expr) command
               If expr (an expression, as described under Expressions) evaluates true, then command is  exe-
               cuted.  Variable substitution on command happens early, at the same time it does for the rest
               of the if command.  command must be a simple command, not an alias,  a  pipeline,  a  command
               list  or  a  parenthesized command list, but it may have arguments.  Input/output redirection
               occurs even if expr is false and command is thus not executed; this is a bug.

       if (expr) then
       else if (expr2) then
       endif   If the specified expr is true then the commands to the first else are executed; otherwise  if
               expr2  is true then the commands to the second else are executed, etc.  Any number of else-if
               pairs are possible; only one endif is needed.  The else  part  is  likewise  optional.   (The
               words else and endif must appear at the beginning of input lines; the if must appear alone on
               its input line or after an else.)

       inlib shared-library ... (+)
               Adds each shared-library to the current environment.  There is no  way  to  remove  a  shared
               library.  (Domain/OS only)

       jobs [-l]
               Lists the active jobs.  With -l, lists process IDs in addition to the normal information.  On
               TCF systems, prints the site on which each job is executing.

       kill [-s signal] %job|pid ...
       kill -l The first and second forms sends the specified signal (or, if none is given, the TERM (termi-
               nate)  signal)  to  the specified jobs or processes.  job may be a number, a string, `', `%',
               `+' or `-' as described under Jobs.  Signals are either given by number or by name (as  given
               in  /usr/include/signal.h,  stripped  of  the prefix `SIG').  There is no default job; saying
               just `kill' does not send a signal to the current job.  If the  signal  being  sent  is  TERM
               (terminate)  or  HUP  (hangup),  then  the job or process is sent a CONT (continue) signal as
               well.  The third form lists the signal names.

       limit [-h] [resource [maximum-use]]
               Limits the consumption by the current process and each process it creates to not individually
               exceed  maximum-use  on the specified resource.  If no maximum-use is given, then the current
               limit is printed; if no resource is given, then all limitations are given.  If the -h flag is
               given,  the  hard  limits  are  used instead of the current limits.  The hard limits impose a
               ceiling on the values of the current limits.  Only the super-user may raise the hard  limits,
               but a user may lower or raise the current limits within the legal range.

               Controllable resources currently include (if supported by the OS):

                      the maximum number of cpu-seconds to be used by each process

                      the largest single file which can be created

                      the  maximum growth of the data+stack region via sbrk(2) beyond the end of the program

                      the maximum size of the automatically-extended stack region

                      the size of the largest core dump that will be created

                      the maximum amount of physical memory a process may have allocated to it  at  a  given

                      the maximum amount of memory a process may allocate per brk() system call

               descriptors or openfiles
                      the maximum number of open files for this process

                      the maximum number of threads for this process

                      the maximum size which a process may lock into memory using mlock(2)

                      the maximum number of simultaneous processes for this user id

               sbsize the maximum size of socket buffer usage for this user

               maximum-use  may be given as a (floating point or integer) number followed by a scale factor.
               For all limits other than cputime the default scale is `k' or  `kilobytes'  (1024  bytes);  a
               scale  factor  of  `m'  or  `megabytes' may also be used.  For cputime the default scaling is
               `seconds', while `m' for minutes or `h' for hours, or a time of the form `mm:ss' giving  min-
               utes and seconds may be used.

               For both resource names and scale factors, unambiguous prefixes of the names suffice.

       log (+) Prints the watch shell variable and reports on each user indicated in watch who is logged in,
               regardless of when they last logged in.  See also watchlog.

       login   Terminates a login shell, replacing it with an instance of /bin/login. This is one way to log
               off, included for compatibility with sh(1).

       logout  Terminates a login shell.  Especially useful if ignoreeof is set.

       ls-F [-switch ...] [file ...] (+)
               Lists  files  like  `ls -F', but much faster.  It identifies each type of special file in the
               listing with a special character:

               /   Directory
               *   Executable
               #   Block device
               %   Character device
               |   Named pipe (systems with named pipes only)
               =   Socket (systems with sockets only)
               @   Symbolic link (systems with symbolic links only)
               +   Hidden directory (AIX only) or context dependent (HP/UX only)
               :   Network special (HP/UX only)

               If the listlinks shell variable is set, symbolic links are identified in more detail (on only
               systems that have them, of course):

               @   Symbolic link to a non-directory
               >   Symbolic link to a directory
               &   Symbolic link to nowhere

               listlinks  also  slows  down  ls-F and causes partitions holding files pointed to by symbolic
               links to be mounted.

               If the listflags shell variable is set to `x', `a' or `A', or any combination thereof  (e.g.,
               `xA'),  they  are used as flags to ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a
               combination (e.g., `ls -FxA').  On machines where `ls -C' is not the default, ls-F acts  like
               `ls -CF', unless listflags contains an `x', in which case it acts like `ls -xF'.  ls-F passes
               its arguments to ls(1) if it is given any switches, so `alias ls  ls-F'  generally  does  the
               right thing.

               The  ls-F  builtin  can list files using different colors depending on the filetype or exten-
               sion.  See the color tcsh variable and the LS_COLORS environment variable.

       migrate [-site] pid|%jobid ... (+)
       migrate -site (+)
               The first form migrates the process or job to the site specified or the default  site  deter-
               mined  by  the system path.  The second form is equivalent to `migrate -site $$': it migrates
               the current process to the specified site.  Migrating the shell itself can  cause  unexpected
               behavior, because the shell does not like to lose its tty.  (TCF only)

       newgrp [-] group (+)
               Equivalent to `exec newgrp'; see newgrp(1).  Available only if the shell was so compiled; see
               the version shell variable.

       nice [+number] [command]
               Sets the scheduling priority for the shell to number, or, without number, to  4.   With  com-
               mand,  runs  command  at  the appropriate priority.  The greater the number, the less cpu the
               process gets.  The super-user may specify negative priority  by  using  `nice  -number  ...'.
               Command  is always executed in a sub-shell, and the restrictions placed on commands in simple
               if statements apply.

       nohup [command]
               With command, runs command such that it will ignore hangup signals.  Note that  commands  may
               set  their own response to hangups, overriding nohup.  Without an argument (allowed in only a
               shell script), causes the shell to ignore hangups for the remainder of the script.  See  also
               Signal handling and the hup builtin command.

       notify [%job ...]
               Causes  the  shell  to notify the user asynchronously when the status of any of the specified
               jobs (or, without %job, the current job) changes, instead of waiting until the next prompt as
               is  usual.   job may be a number, a string, `', `%', `+' or `-' as described under Jobs.  See
               also the notify shell variable.

       onintr [-|label]
               Controls the action of the shell on interrupts.   Without  arguments,  restores  the  default
               action  of  the  shell on interrupts, which is to terminate shell scripts or to return to the
               terminal command input level.  With `-', causes all interrupts to be  ignored.   With  label,
               causes  the  shell to execute a `goto label' when an interrupt is received or a child process
               terminates because it was interrupted.

               onintr is ignored if the shell is running detached and in system startup files  (see  FILES),
               where interrupts are disabled anyway.

       popd [-p] [-l] [-n|-v] [+n]
               Without  arguments,  pops  the  directory stack and returns to the new top directory.  With a
               number `+n', discards the n'th entry in the stack.

               Finally, all forms of popd print the final directory stack, just like dirs.  The  pushdsilent
               shell  variable  can be set to prevent this and the -p flag can be given to override pushdsi-
               lent.  The -l, -n and -v flags have the same effect on popd as on dirs.  (+)

       printenv [name] (+)
               Prints the names and values of all environment variables or, with  name,  the  value  of  the
               environment variable name.

       pushd [-p] [-l] [-n|-v] [name|+n]
               Without  arguments, exchanges the top two elements of the directory stack.  If pushdtohome is
               set, pushd without arguments does `pushd ~', like cd.  (+)  With  name,  pushes  the  current
               working  directory onto the directory stack and changes to name.  If name is `-' it is inter-
               preted as the previous working directory (see Filename substitution).  (+) If dunique is set,
               pushd  removes  any  instances  of name from the stack before pushing it onto the stack.  (+)
               With a number `+n', rotates the nth element of the directory stack around to be the top  ele-
               ment  and changes to it.  If dextract is set, however, `pushd +n' extracts the nth directory,
               pushes it onto the top of the stack and changes to it.  (+)

               Finally, all forms of pushd print the final directory stack, just like dirs.  The pushdsilent
               shell  variable  can be set to prevent this and the -p flag can be given to override pushdsi-
               lent.  The -l, -n and -v flags have the same effect on pushd as on dirs.  (+)

       rehash  Causes the internal hash table of the contents of the directories in the path variable to  be
               recomputed.   This  is  needed if new commands are added to directories in path while you are
               logged in.  This should be necessary only if you add commands to one of your own directories,
               or  if  a  systems  programmer  changes  the contents of one of the system directories.  Also
               flushes the cache of home directories built by tilde expansion.

       repeat count command
               The specified command, which is subject to the same restrictions as the command  in  the  one
               line  if statement above, is executed count times.  I/O redirections occur exactly once, even
               if count is 0.

       rootnode //nodename (+)
               Changes the rootnode to  //nodename,  so  that  `/'  will  be  interpreted  as  `//nodename'.
               (Domain/OS only)

       sched (+)
       sched [+]hh:mm command (+)
       sched -n (+)
               The  first  form  prints  the  scheduled-event  list.  The sched shell variable may be set to
               define the format in which the scheduled-event list is printed.  The second form adds command
               to the scheduled-event list.  For example,

                   > sched 11:00 echo It\'s eleven o\'clock.

               causes  the  shell to echo `It's eleven o'clock.' at 11 AM.  The time may be in 12-hour AM/PM

                   > sched 5pm set prompt='[%h] It\'s after 5; go home: >'

               or may be relative to the current time:

                   > sched +2:15 /usr/lib/uucp/uucico -r1 -sother

               A relative time specification may not use AM/PM format.  The third form removes item  n  from
               the event list:

                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother
                        2  Wed Apr  4 17:00  set prompt=[%h] It's after 5; go home: >
                   > sched -2
                   > sched
                        1  Wed Apr  4 15:42  /usr/lib/uucp/uucico -r1 -sother

               A  command  in  the  scheduled-event list is executed just before the first prompt is printed
               after the time when the command is scheduled.  It is possible to miss the exact time when the
               command  is  to  be  run,  but an overdue command will execute at the next prompt.  A command
               which comes due while the shell is waiting for user input is executed immediately.   However,
               normal  operation  of an already-running command will not be interrupted so that a scheduled-
               event list element may be run.

               This mechanism is similar to, but not the same as, the at(1) command on  some  Unix  systems.
               Its  major  disadvantage is that it may not run a command at exactly the specified time.  Its
               major advantage is that because sched runs directly from the shell, it has  access  to  shell
               variables  and  other structures.  This provides a mechanism for changing one's working envi-
               ronment based on the time of day.

       set name ...
       set name=word ...
       set [-r] [-f|-l] name=(wordlist) ... (+)
       set name[index]=word ...
       set -r (+)
       set -r name ... (+)
       set -r name=word ... (+)
               The first form of the command prints the value of all shell variables.  Variables which  con-
               tain  more  than a single word print as a parenthesized word list.  The second form sets name
               to the null string.  The third form sets name to the single word.  The fourth form sets  name
               to  the  list of words in wordlist.  In all cases the value is command and filename expanded.
               If -r is specified, the value is set read-only.  If -f or -l are specified, set  only  unique
               words  keeping their order.  -f prefers the first occurrence of a word, and -l the last.  The
               fifth form sets the index'th component of name to word; this component  must  already  exist.
               The  sixth  form lists only the names of all shell variables that are read-only.  The seventh
               form makes name read-only, whether or not it has a value.  The second form sets name  to  the
               null  string.   The eighth form is the same as the third form, but make name read-only at the
               same time.

               These arguments can be repeated to set and/or make read-only multiple variables in  a  single
               set  command.   Note,  however,  that variable expansion happens for all arguments before any
               setting occurs.  Note also that `=' can be adjacent to both name and word or  separated  from
               both  by  whitespace,  but  cannot  be adjacent to only one or the other.  See also the unset
               builtin command.

       setenv [name [value]]
               Without arguments, prints the names and values of all  environment  variables.   Given  name,
               sets the environment variable name to value or, without value, to the null string.

       setpath path (+)
               Equivalent to setpath(1).  (Mach only)

       setspath LOCAL|site|cpu ... (+)
               Sets the system execution path.  (TCF only)

       settc cap value (+)
               Tells  the  shell  to believe that the terminal capability cap (as defined in termcap(5)) has
               the value value.  No sanity checking is done.  Concept terminal users may have to  `settc  xn
               no' to get proper wrapping at the rightmost column.

       setty [-d|-q|-x] [-a] [[+|-]mode] (+)
               Controls  which  tty modes (see Terminal management) the shell does not allow to change.  -d,
               -q or -x tells setty to act on the `edit', `quote' or `execute'  set  of  tty  modes  respec-
               tively; without -d, -q or -x, `execute' is used.

               Without other arguments, setty lists the modes in the chosen set which are fixed on (`+mode')
               or off (`-mode').  The available modes, and thus the display, vary  from  system  to  system.
               With  -a,  lists  all tty modes in the chosen set whether or not they are fixed.  With +mode,
               -mode or mode, fixes mode on or off or removes control from mode  in  the  chosen  set.   For
               example,  `setty +echok echoe' fixes `echok' mode on and allows commands to turn `echoe' mode
               on or off, both when the shell is executing commands.

       setxvers [string] (+)
               Set the experimental version prefix to string, or removes it  if  string  is  omitted.   (TCF

       shift [variable]
               Without  arguments,  discards  argv[1]  and shifts the members of argv to the left.  It is an
               error for argv not to be set or to have less than one word as value.  With variable, performs
               the same function on variable.

       source [-h] name [args ...]
               The  shell reads and executes commands from name.  The commands are not placed on the history
               list.  If any args are given, they are placed in argv.  (+) source commands may be nested; if
               they  are  nested too deeply the shell may run out of file descriptors.  An error in a source
               at any level terminates all nested source commands.  With -h, commands are placed on the his-
               tory list instead of being executed, much like `history -L'.

       stop %job|pid ...
               Stops  the  specified  jobs or processes which are executing in the background.  job may be a
               number, a string, `', `%', `+' or `-' as described under Jobs.  There is no default job; say-
               ing just `stop' does not stop the current job.

       suspend Causes  the  shell  to stop in its tracks, much as if it had been sent a stop signal with ^Z.
               This is most often used to stop shells started by su(1).

       switch (string)
       case str1:
       endsw   Each case label is successively matched, against the specified string which is first  command
               and filename expanded.  The file metacharacters `*', `?' and `[...]'  may be used in the case
               labels, which are variable expanded.  If none of the labels match before a `default' label is
               found,  then  the  execution begins after the default label.  Each case label and the default
               label must appear at the beginning of a line.  The command breaksw causes execution  to  con-
               tinue  after the endsw.  Otherwise control may fall through case labels and default labels as
               in C.  If no label matches and there is no default, execution continues after the endsw.

       telltc (+)
               Lists the values of all terminal capabilities (see termcap(5)).

       termname [terminal type] (+)
               Tests if terminal type (or the current value of TERM if no terminal type  is  given)  has  an
               entry in the hosts termcap(5) or terminfo(5) database. Prints the terminal type to stdout and
               returns 0 if an entry is present otherwise returns 1.

       time [command]
               Executes command (which must be a simple command, not an alias, a pipeline, a command list or
               a parenthesized command list) and prints a time summary as described under the time variable.
               If necessary, an extra shell is created to print the time statistic  when  the  command  com-
               pletes.  Without command, prints a time summary for the current shell and its children.

       umask [value]
               Sets  the  file  creation mask to value, which is given in octal.  Common values for the mask
               are 002, giving all access to the group and read and execute access to others, and 022,  giv-
               ing  read and execute access to the group and others.  Without value, prints the current file
               creation mask.

       unalias pattern
               Removes all aliases whose names match pattern.  `unalias *' thus removes all aliases.  It  is
               not an error for nothing to be unaliased.

       uncomplete pattern (+)
               Removes  all  completions whose names match pattern.  `uncomplete *' thus removes all comple-
               tions.  It is not an error for nothing to be uncompleted.

       unhash  Disables use of the internal hash table to speed location of executed programs.

       universe universe (+)
               Sets the universe to universe.  (Masscomp/RTU only)

       unlimit [-h] [resource]
               Removes the limitation on resource or, if no resource is specified, all resource limitations.
               With  -h,  the corresponding hard limits are removed.  Only the super-user may do this.  Note
               that unlimit may not exit successful, since most systems  do  not  allow  descriptors  to  be

       unset pattern
               Removes  all  variables whose names match pattern, unless they are read-only.  `unset *' thus
               removes all variables unless they are read-only; this is a bad idea.  It is not an error  for
               nothing to be unset.

       unsetenv pattern
               Removes  all  environment variables whose names match pattern.  `unsetenv *' thus removes all
               environment variables; this is a bad idea.  It is not an error for nothing to be  unsetenved.

       ver [systype [command]] (+)
               Without  arguments, prints SYSTYPE.  With systype, sets SYSTYPE to systype.  With systype and
               command, executes command under systype.  systype may be `bsd4.3'  or  `sys5.3'.   (Domain/OS

       wait    The shell waits for all background jobs.  If the shell is interactive, an interrupt will dis-
               rupt the wait and cause the shell to print the names and job numbers of all outstanding jobs.

       warp universe (+)
               Sets the universe to universe.  (Convex/OS only)

       watchlog (+)
               An  alternate  name  for  the log builtin command (q.v.).  Available only if the shell was so
               compiled; see the version shell variable.

       where command (+)
               Reports all known instances of command, including aliases, builtins and executables in  path.

       which command (+)
               Displays  the command that will be executed by the shell after substitutions, path searching,
               etc.  The builtin command is just like which(1), but it correctly reports  tcsh  aliases  and
               builtins and is 10 to 100 times faster.  See also the which-command editor command.

       while (expr)
       end     Executes  the  commands  between the while and the matching end while expr (an expression, as
               described under Expressions) evaluates non-zero.  while and end must appear  alone  on  their
               input  lines.   break and continue may be used to terminate or continue the loop prematurely.
               If the input is a terminal, the user is prompted the first time  through  the  loop  as  with

   Special aliases (+)
       If  set,  each of these aliases executes automatically at the indicated time.  They are all initially

       beepcmd Runs when the shell wants to ring the terminal bell.

       cwdcmd  Runs after every change of working directory.  For example, if the user is working  on  an  X
               window  system using xterm(1) and a re-parenting window manager that supports title bars such
               as twm(1) and does

                   > alias cwdcmd  'echo -n "^[]2;${HOST}:$cwd ^G"'

               then the shell will change the title of the running xterm(1) to be the name of  the  host,  a
               colon, and the full current working directory.  A fancier way to do that is

                   > alias cwdcmd 'echo -n "^[]2;${HOST}:$cwd^G^[]1;${HOST}^G"'

               This  will  put  the hostname and working directory on the title bar but only the hostname in
               the icon manager menu.

               Note that putting a cd, pushd or popd in cwdcmd may  cause  an  infinite  loop.   It  is  the
               author's opinion that anyone doing so will get what they deserve.

       jobcmd  Runs  before  each command gets executed, or when the command changes state.  This is similar
               to postcmd, but it does not print builtins.

                   > alias jobcmd  'echo -n "^[]2\;\!#^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

               Invoked by the run-help editor command.  The command name for which help is sought is  passed
               as sole argument.  For example, if one does

                   > alias helpcommand '\!:1 --help'

               then  the help display of the command itself will be invoked, using the GNU help calling con-
               vention.  Currently there is no easy way to account for various  calling  conventions  (e.g.,
               the customary Unix `-h'), except by using a table of many commands.

               Runs  every  tperiod  minutes.   This  provides a convenient means for checking on common but
               infrequent changes such as new mail.  For example, if one does

                   > set tperiod = 30
                   > alias periodic checknews

               then the checknews(1) program runs every 30 minutes.  If periodic is set but tperiod is unset
               or set to 0, periodic behaves like precmd.

       precmd  Runs just before each prompt is printed.  For example, if one does

                   > alias precmd date

               then  date(1)  runs  just  before the shell prompts for each command.  There are no limits on
               what precmd can be set to do, but discretion should be used.

       postcmd Runs before each command gets executed.

                   > alias postcmd  'echo -n "^[]2\;\!#^G"'

               then executing vi foo.c will put the command string in the xterm title bar.

       shell   Specifies the interpreter for executable scripts which do not themselves  specify  an  inter-
               preter.   The  first  word  should  be  a  full  path  name to the desired interpreter (e.g.,
               `/bin/csh' or `/usr/local/bin/tcsh').

   Special shell variables
       The variables described in this section have special meaning to the shell.

       The shell sets addsuffix, argv, autologout, csubstnonl, command, echo_style, edit, gid, group,  home,
       loginsh, oid, path, prompt, prompt2, prompt3, shell, shlvl, tcsh, term, tty, uid, user and version at
       startup; they do not change thereafter unless changed by the user.  The shell updates cwd,  dirstack,
       owd and status when necessary, and sets logout on logout.

       The  shell  synchronizes  afsuser, group, home, path, shlvl, term and user with the environment vari-
       ables of the same names: whenever the environment variable changes the shell changes the  correspond-
       ing  shell  variable  to  match  (unless  the shell variable is read-only) and vice versa.  Note that
       although cwd and PWD have identical meanings, they are not synchronized in this manner, and that  the
       shell automatically interconverts the different formats of path and PATH.

       addsuffix (+)
               If set, filename completion adds `/' to the end of directories and a space to the end of nor-
               mal files when they are matched exactly.  Set by default.

       afsuser (+)
               If set, autologout's autolock feature uses its value instead of the local username  for  ker-
               beros authentication.

       ampm (+)
               If set, all times are shown in 12-hour AM/PM format.

       argv    The  arguments  to  the  shell.   Positional  parameters  are  taken from argv, i.e., `$1' is
               replaced by `$argv[1]', etc.  Set by default, but usually empty in interactive shells.

       autocorrect (+)
               If set, the spell-word  editor  command  is  invoked  automatically  before  each  completion

       autoexpand (+)
               If  set,  the  expand-history  editor command is invoked automatically before each completion

       autolist (+)
               If set, possibilities are listed after an ambiguous completion.  If set to `ambiguous',  pos-
               sibilities are listed only when no new characters are added by completion.

       autologout (+)
               The  first word is the number of minutes of inactivity before automatic logout.  The optional
               second word is the number of minutes of inactivity before automatic locking.  When the  shell
               automatically  logs out, it prints `auto-logout', sets the variable logout to `automatic' and
               exits.  When the shell automatically locks, the user is required to  enter  his  password  to
               continue  working.   Five  incorrect attempts result in automatic logout.  Set to `60' (auto-
               matic logout after 60 minutes, and no locking) by default in login and superuser shells,  but
               not  if  the  shell thinks it is running under a window system (i.e., the DISPLAY environment
               variable is set), the tty is a pseudo-tty (pty) or the shell was not  so  compiled  (see  the
               version shell variable).  See also the afsuser and logout shell variables.

       backslash_quote (+)
               If  set,  backslashes  (`\')  always  quote `\', `'', and `"'.  This may make complex quoting
               tasks easier, but it can cause syntax errors in csh(1) scripts.

       catalog The file name of the message catalog.  If set, tcsh use `tcsh.${catalog}' as a message  cata-
               log instead of default `tcsh'.

       cdpath  A  list  of  directories in which cd should search for subdirectories if they aren't found in
               the current directory.

       color   If set, it enables color display for the builtin ls-F  and  it  passes  --color=auto  to  ls.
               Alternatively,  it  can  be  set to only ls-F or only ls to enable color to only one command.
               Setting it to nothing is equivalent to setting it to (ls-F ls).

               If set, it enables color escape sequence for NLS message files.   And  display  colorful  NLS

       command (+)
               If set, the command which was passed to the shell with the -c flag (q.v.).

       complete (+)
               If  set to `enhance', completion 1) ignores case and 2) considers periods, hyphens and under-
               scores (`.', `-' and `_') to be word separators and hyphens and underscores to be equivalent.
               If set to `igncase', the completion becomes case insensitive.

       continue (+)
               If  set to a list of commands, the shell will continue the listed commands, instead of start-
               ing a new one.

       continue_args (+)
               Same as continue, but the shell will execute:

                   echo `pwd` $argv > ~/.<cmd>_pause; %<cmd>

       correct (+)
               If set to `cmd', commands are automatically spelling-corrected.  If set to  `complete',  com-
               mands are automatically completed.  If set to `all', the entire command line is corrected.

       csubstnonl (+)
               If set, newlines and carriage returns in command substitution are replaced by spaces.  Set by

       cwd     The full pathname of the current directory.  See also the dirstack and owd shell variables.

       dextract (+)
               If set, `pushd +n' extracts the nth directory from the directory stack rather  than  rotating
               it to the top.

       dirsfile (+)
               The  default  location  in  which `dirs -S' and `dirs -L' look for a history file.  If unset,
               ~/.cshdirs is used.  Because only ~/.tcshrc is normally sourced before  ~/.cshdirs,  dirsfile
               should be set in ~/.tcshrc rather than ~/.login.

       dirstack (+)
               An  array of all the directories on the directory stack.  `$dirstack[1]' is the current work-
               ing directory, `$dirstack[2]' the first directory on the stack, etc.  Note that  the  current
               working  directory is `$dirstack[1]' but `=0' in directory stack substitutions, etc.  One can
               change the stack arbitrarily by setting dirstack, but the first element (the current  working
               directory) is always correct.  See also the cwd and owd shell variables.

       dspmbyte (+)
               Has  an  affect iff 'dspm' is listed as part of the version shell variable.  If set to `euc',
               it enables display and editing EUC-kanji(Japanese) code.  If set to `sjis', it  enables  dis-
               play  and editing Shift-JIS(Japanese) code.  If set to `big5', it enables display and editing
               Big5(Chinese) code.  If set to `utf8', it enables display and editing Utf8(Unicode) code.  If
               set  to the following format, it enables display and editing of original multi-byte code for-

                   > set dspmbyte = 0000....(256 bytes)....0000

               The table requires just 256 bytes.  Each character of 256 characters corresponds  (from  left
               to right) to the ASCII codes 0x00, 0x01, ... 0xff.  Each character is set to number 0,1,2 and
               3.  Each number has the following meaning:
                 0 ... not used for multi-byte characters.
                 1 ... used for the first byte of a multi-byte character.
                 2 ... used for the second byte of a multi-byte character.
                 3 ... used for both the first byte and second byte of a multi-byte character.

               If set to `001322', the first character (means 0x00 of the ASCII code) and  second  character
               (means  0x01  of ASCII code) are set to `0'.  Then, it is not used for multi-byte characters.
               The 3rd character (0x02) is set to '1', indicating that it is used for the first  byte  of  a
               multi-byte  character.   The  4th  character(0x03) is set '3'.  It is used for both the first
               byte and the second byte of a multi-byte character.  The 5th and 6th  characters  (0x04,0x05)
               are  set to '2', indicating that they are used for the second byte of a multi-byte character.

               The GNU fileutils version of ls cannot display multi-byte filenames without the -N  (  --lit-
               eral  ) option.   If you are using this version, set the second word of dspmbyte to "ls".  If
               not, for example, "ls-F -l" cannot display multi-byte filenames.

               This variable can only be used if KANJI and DSPMBYTE has been defined at compile time.

       dunique (+)
               If set, pushd removes any instances of name from the stack before pushing it onto the  stack.

       echo    If  set,  each  command  with  its  arguments is echoed just before it is executed.  For non-
               builtin commands all expansions occur before echoing.  Builtin  commands  are  echoed  before
               command  and  filename  substitution,  because these substitutions are then done selectively.
               Set by the -x command line option.

       echo_style (+)
               The style of the echo builtin.  May be set to

               bsd     Don't echo a newline if the first argument is `-n'.
               sysv    Recognize backslashed escape sequences in echo strings.
               both    Recognize both the `-n' flag and backslashed escape sequences; the default.
               none    Recognize neither.

               Set by default to the local system default.  The BSD and System V options  are  described  in
               the echo(1) man pages on the appropriate systems.

       edit (+)
               If set, the command-line editor is used.  Set by default in interactive shells.

       ellipsis (+)
               If  set,  the  `%c'/`%.'  and  `%C' prompt sequences (see the prompt shell variable) indicate
               skipped directories with an ellipsis (`...')  instead of `/<skipped>'.

       fignore (+)
               Lists file name suffixes to be ignored by completion.

       filec   In tcsh, completion is always used and this variable is ignored by default. If edit is unset,
               then the traditional csh completion is used.  If set in csh, filename completion is used.

       gid (+) The user's real group ID.

       group (+)
               The user's group name.

               A  string  value  determining  the characters used in History substitution (q.v.).  The first
               character of its value is used as the history substitution character, replacing  the  default
               character `!'.  The second character of its value replaces the character `^' in quick substi-

       histdup (+)
               Controls handling of duplicate entries in the history list.  If set to `all' only unique his-
               tory  events are entered in the history list.  If set to `prev' and the last history event is
               the same as the current command, then the current command is not entered in the history.   If
               set  to  `erase'  and the same event is found in the history list, that old event gets erased
               and the current one gets inserted.  Note that the `prev' and `all' options  renumber  history
               events so there are no gaps.

       histfile (+)
               The  default  location  in  which  `history -S' and `history -L' look for a history file.  If
               unset, ~/.history is used.  histfile is useful when sharing the same home  directory  between
               different  machines,  or when saving separate histories on different terminals.  Because only
               ~/.tcshrc is normally sourced before ~/.history, histfile should be set in  ~/.tcshrc  rather
               than ~/.login.

       histlit (+)
               If  set,  builtin and editor commands and the savehist mechanism use the literal (unexpanded)
               form of lines in the history list.  See also the toggle-literal-history editor command.

       history The first word indicates the number of history events to save.  The optional second word  (+)
               indicates  the format in which history is printed; if not given, `%h\t%T\t%R\n' is used.  The
               format sequences are described below under prompt; note the variable meaning of `%R'.  Set to
               `100' by default.

       home    Initialized  to  the  home directory of the invoker.  The filename expansion of `~' refers to
               this variable.

               If set to the empty string or `0' and the input device is a terminal, the end-of-file command
               (usually  generated  by  the  user by typing `^D' on an empty line) causes the shell to print
               `Use "exit" to leave tcsh.' instead of exiting.  This prevents the  shell  from  accidentally
               being  killed.   Historically this setting exited after 26 successive EOF's to avoid infinite
               loops.  If set to a number n, the shell ignores n - 1 consecutive end-of-files and  exits  on
               the nth.  (+) If unset, `1' is used, i.e., the shell exits on a single `^D'.

       implicitcd (+)
               If  set,  the shell treats a directory name typed as a command as though it were a request to
               change to that directory.  If set to verbose, the change of directory is echoed to the  stan-
               dard  output.   This  behavior  is inhibited in non-interactive shell scripts, or for command
               strings with more than one word.  Changing directory takes precedence over executing a  like-
               named  command, but it is done after alias substitutions.  Tilde and variable expansions work
               as expected.

       inputmode (+)
               If set to `insert' or `overwrite', puts the editor into that input mode at the  beginning  of
               each line.

       killdup (+)
               Controls handling of duplicate entries in the kill ring.  If set to `all' only unique strings
               are entered in the kill ring.  If set to `prev' and the last killed string is the same as the
               current killed string, then the current string is not entered in the ring.  If set to `erase'
               and the same string is found in the kill ring, the old string is erased and the  current  one
               is inserted.

       killring (+)
               Indicates  the number of killed strings to keep in memory.  Set to `30' by default.  If unset
               or set to less than `2', the shell will only keep the most recently killed  string.   Strings
               are put in the killring by the editor commands that delete (kill) strings of text, e.g. back-
               ward-delete-word, kill-line, etc, as well as the copy-region-as-kill command.  The yank  edi-
               tor  command  will yank the most recently killed string into the command-line, while yank-pop
               (see Editor commands) can be used to yank earlier killed strings.

       listflags (+)
               If set to `x', `a' or `A', or any combination thereof (e.g., `xA'), they are used as flags to
               ls-F, making it act like `ls -xF', `ls -Fa', `ls -FA' or a combination (e.g., `ls -FxA'): `a'
               shows all files (even if they start with a `.'), `A' shows all files but `.'  and  `..',  and
               `x'  sorts across instead of down.  If the second word of listflags is set, it is used as the
               path to `ls(1)'.

       listjobs (+)
               If set, all jobs are listed when a job is suspended.  If set to `long',  the  listing  is  in
               long format.

       listlinks (+)
               If set, the ls-F builtin command shows the type of file to which each symbolic link points.

       listmax (+)
               The  maximum  number  of items which the list-choices editor command will list without asking

       listmaxrows (+)
               The maximum number of rows of items which the list-choices editor command will  list  without
               asking first.

       loginsh (+)
               Set  by  the  shell  if  it  is a login shell.  Setting or unsetting it within a shell has no
               effect.  See also shlvl.

       logout (+)
               Set by the shell to `normal' before a normal logout, `automatic' before an automatic  logout,
               and  `hangup' if the shell was killed by a hangup signal (see Signal handling).  See also the
               autologout shell variable.

       mail    The names of the files or directories to check for incoming mail,  separated  by  whitespace,
               and  optionally  preceded  by  a numeric word.  Before each prompt, if 10 minutes have passed
               since the last check, the shell checks each file and says `You have new mail.' (or,  if  mail
               contains  multiple  files, `You have new mail in name.') if the filesize is greater than zero
               in size and has a modification time greater than its access time.

               If you are in a login shell, then no mail file is reported unless it has been modified  after
               the  time  the shell has started up, to prevent redundant notifications.  Most login programs
               will tell you whether or not you have mail when you log in.

               If a file specified in mail is a directory, the shell will count each file within that direc-
               tory  as  a  separate  message,  and  will report `You have n mails.' or `You have n mails in
               name.' as appropriate.  This functionality is provided  primarily  for  those  systems  which
               store mail in this manner, such as the Andrew Mail System.

               If  the  first  word of mail is numeric it is taken as a different mail checking interval, in

               Under very rare circumstances, the shell may report `You have mail.' instead of `You have new

       matchbeep (+)
               If  set to `never', completion never beeps.  If set to `nomatch', it beeps only when there is
               no match.  If set to `ambiguous', it beeps when there are multiple matches.  If set to `notu-
               nique',  it beeps when there is one exact and other longer matches.  If unset, `ambiguous' is

       nobeep (+)
               If set, beeping is completely disabled.  See also visiblebell.

               If set, restrictions are placed on output redirection to insure that files are  not  acciden-
               tally  destroyed  and  that  `>>'  redirections  refer to existing files, as described in the
               Input/output section.

       noding  If set, disable the printing of `DING!' in the prompt time specifiers at the change of  hour.

       noglob  If set, Filename substitution and Directory stack substitution (q.v.) are inhibited.  This is
               most useful in shell scripts which do not deal with filenames, or after a list  of  filenames
               has been obtained and further expansions are not desirable.

       nokanji (+)
               If  set and the shell supports Kanji (see the version shell variable), it is disabled so that
               the meta key can be used.

               If set, a Filename substitution or Directory stack substitution (q.v.) which does  not  match
               any  existing files is left untouched rather than causing an error.  It is still an error for
               the substitution to be malformed, e.g., `echo [' still gives an error.

       nostat (+)
               A list of directories (or glob-patterns which match directories; see  Filename  substitution)
               that  should not be stat(2)ed during a completion operation.  This is usually used to exclude
               directories which take too much time to stat(2), for example /afs.

       notify  If set, the shell announces job completions asynchronously.  The default is  to  present  job
               completions just before printing a prompt.

       oid (+) The user's real organization ID.  (Domain/OS only)

       owd (+) The  old working directory, equivalent to the `-' used by cd and pushd.  See also the cwd and
               dirstack shell variables.

       path    A list of directories in which to look for executable commands.  A null  word  specifies  the
               current  directory.   If  there  is  no path variable then only full path names will execute.
               path is set by the shell at startup from the PATH environment variable or, if PATH  does  not
               exist,  to  a system-dependent default something like `(/usr/local/bin /usr/bsd /bin /usr/bin
               .)'.  The shell may put `.' first or last in path or omit it entirely depending on how it was
               compiled;  see  the version shell variable.  A shell which is given neither the -c nor the -t
               option hashes the contents of the directories in path after reading ~/.tcshrc and  each  time
               path  is  reset.  If one adds a new command to a directory in path while the shell is active,
               one may need to do a rehash for the shell to find it.

       printexitvalue (+)
               If set and an interactive program exits with a non-zero status, the shell prints  `Exit  sta-

       prompt  The  string  which  is  printed  before  reading  each command from the terminal.  prompt may
               include any of the following formatting sequences (+), which are replaced by the given infor-

               %/  The current working directory.
               %~  The current working directory, but with one's home directory represented by `~' and other
                   users' home directories represented by `~user' as  per  Filename  substitution.   `~user'
                   substitution happens only if the shell has already used `~user' in a pathname in the cur-
                   rent session.
               %c[[0]n], %.[[0]n]
                   The trailing component of the current working directory, or n trailing  components  if  a
                   digit  n  is  given.   If n begins with `0', the number of skipped components precede the
                   trailing component(s) in the format `/<skipped>trailing'.  If the ellipsis shell variable
                   is set, skipped components are represented by an ellipsis so the whole becomes `...trail-
                   ing'.  `~' substitution is done as in `%~' above, but the `~' component is  ignored  when
                   counting trailing components.
               %C  Like %c, but without `~' substitution.
               %h, %!, !
                   The current history event number.
               %M  The full hostname.
               %m  The hostname up to the first `.'.
               %S (%s)
                   Start (stop) standout mode.
               %B (%b)
                   Start (stop) boldfacing mode.
               %U (%u)
                   Start (stop) underline mode.
               %t, %@
                   The time of day in 12-hour AM/PM format.
               %T  Like `%t', but in 24-hour format (but see the ampm shell variable).
               %p  The `precise' time of day in 12-hour AM/PM format, with seconds.
               %P  Like `%p', but in 24-hour format (but see the ampm shell variable).
               \c  c is parsed as in bindkey.
               ^c  c is parsed as in bindkey.
               %%  A single `%'.
               %n  The user name.
               %j  The number of jobs.
               %d  The weekday in `Day' format.
               %D  The day in `dd' format.
               %w  The month in `Mon' format.
               %W  The month in `mm' format.
               %y  The year in `yy' format.
               %Y  The year in `yyyy' format.
               %l  The shell's tty.
               %L  Clears from the end of the prompt to end of the display or the end of the line.
               %$  Expands the shell or environment variable name immediately after the `$'.
               %#  `>'  (or the first character of the promptchars shell variable) for normal users, `#' (or
                   the second character of promptchars) for the superuser.
                   Includes string as a literal escape sequence.  It should be used only to change  terminal
                   attributes  and should not move the cursor location.  This cannot be the last sequence in
               %?  The return code of the command executed just before the prompt.
               %R  In prompt2, the status of the parser.  In prompt3, the corrected string.  In history, the
                   history string.

               `%B',  `%S', `%U' and `%{string%}' are available in only eight-bit-clean shells; see the ver-
               sion shell variable.

               The bold, standout and underline sequences are often used to distinguish a  superuser  shell.
               For example,

                   > set prompt = "%m [%h] %B[%@]%b [%/] you rang? "
                   tut [37] [2:54pm] [/usr/accts/sys] you rang? _

               If  `%t', `%@', `%T', `%p', or `%P' is used, and noding is not set, then print `DING!' on the
               change of hour (i.e, `:00' minutes) instead of the actual time.

               Set by default to `%# ' in interactive shells.

       prompt2 (+)
               The string with which to prompt in while and foreach loops and after  lines  ending  in  `\'.
               The same format sequences may be used as in prompt (q.v.); note the variable meaning of `%R'.
               Set by default to `%R? ' in interactive shells.

       prompt3 (+)
               The string with which to prompt when confirming automatic spelling correction.  The same for-
               mat  sequences  may  be  used as in prompt (q.v.); note the variable meaning of `%R'.  Set by
               default to `CORRECT>%R (y|n|e|a)? ' in interactive shells.

       promptchars (+)
               If set (to a two-character string), the `%#' formatting sequence in the prompt shell variable
               is  replaced with the first character for normal users and the second character for the supe-

       pushdtohome (+)
               If set, pushd without arguments does `pushd ~', like cd.

       pushdsilent (+)
               If set, pushd and popd do not print the directory stack.

       recexact (+)
               If set, completion completes on an exact match even if a longer match is possible.

       recognize_only_executables (+)
               If set, command listing displays only files in the path that are executable.  Slow.

       rmstar (+)
               If set, the user is prompted before `rm *' is executed.

       rprompt (+)
               The string to print on the right-hand side of the screen (after the command input)  when  the
               prompt  is  being  displayed  on  the  left.  It recognizes the same formatting characters as
               prompt.  It will automatically disappear and reappear as necessary, to  ensure  that  command
               input  isn't obscured, and will appear only if the prompt, command input, and itself will fit
               together on the first line.  If edit isn't set, then rprompt will be printed after the prompt
               and before the command input.

       savedirs (+)
               If  set,  the  shell does `dirs -S' before exiting.  If the first word is set to a number, at
               most that many directory stack entries are saved.

               If set, the shell does `history -S' before exiting.  If the first word is set to a number, at
               most  that many lines are saved.  (The number must be less than or equal to history.)  If the
               second word is set to `merge', the history list is merged  with  the  existing  history  file
               instead of replacing it (if there is one) and sorted by time stamp and the most recent events
               are retained.  (+)

       sched (+)
               The format in which the  sched  builtin  command  prints  scheduled  events;  if  not  given,
               `%h\t%T\t%R\n'  is  used.   The  format  sequences are described above under prompt; note the
               variable meaning of `%R'.

       shell   The file in which the shell resides.  This is used in forking shells to interpret files which
               have  execute  bits set, but which are not executable by the system.  (See the description of
               Builtin and non-builtin command execution.)  Initialized to the  (system-dependent)  home  of
               the shell.

       shlvl (+)
               The number of nested shells.  Reset to 1 in login shells.  See also loginsh.

       status  The  status returned by the last command.  If it terminated abnormally, then 0200 is added to
               the status.  Builtin commands which fail return exit status `1', all other  builtin  commands
               return status `0'.

       symlinks (+)
               Can be set to several different values to control symbolic link (`symlink') resolution:

               If  set  to  `chase', whenever the current directory changes to a directory containing a sym-
               bolic link, it is expanded to the real name of the directory to which the link points.   This
               does not work for the user's home directory; this is a bug.

               If  set to `ignore', the shell tries to construct a current directory relative to the current
               directory before the link was crossed.  This means that cding through  a  symbolic  link  and
               then  `cd  ..'ing  returns one to the original directory.  This affects only builtin commands
               and filename completion.

               If set to `expand', the shell tries to fix symbolic links  by  actually  expanding  arguments
               which  look  like  path  names.  This affects any command, not just builtins.  Unfortunately,
               this does not work for  hard-to-recognize  filenames,  such  as  those  embedded  in  command
               options.  Expansion may be prevented by quoting.  While this setting is usually the most con-
               venient, it is sometimes misleading and sometimes confusing when it  fails  to  recognize  an
               argument  which  should be expanded.  A compromise is to use `ignore' and use the editor com-
               mand normalize-path (bound by default to ^X-n) when necessary.

               Some examples are in order.  First, let's set up some play directories:

                   > cd /tmp
                   > mkdir from from/src to
                   > ln -s from/src to/dst

               Here's the behavior with symlinks unset,

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to `chase',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               here's the behavior with symlinks set to `ignore',

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd

               and here's the behavior with symlinks set to `expand'.

                   > cd /tmp/to/dst; echo $cwd
                   > cd ..; echo $cwd
                   > cd /tmp/to/dst; echo $cwd
                   > cd ".."; echo $cwd
                   > /bin/echo ..
                   > /bin/echo ".."

               Note that `expand' expansion 1) works just like `ignore' for builtins like  cd,  2)  is  pre-
               vented by quoting, and 3) happens before filenames are passed to non-builtin commands.

       tcsh (+)
               The  version number of the shell in the format `R.VV.PP', where `R' is the major release num-
               ber, `VV' the current version and `PP' the patchlevel.

       term    The terminal type.  Usually set in ~/.login as described under Startup and shutdown.

       time    If set to a number, then the time builtin (q.v.) executes automatically  after  each  command
               which takes more than that many CPU seconds.  If there is a second word, it is used as a for-
               mat string for the output of the time builtin.  (u) The following sequences may  be  used  in
               the format string:

               %U  The time the process spent in user mode in cpu seconds.
               %S  The time the process spent in kernel mode in cpu seconds.
               %E  The elapsed (wall clock) time in seconds.
               %P  The CPU percentage computed as (%U + %S) / %E.
               %W  Number of times the process was swapped.
               %X  The average amount in (shared) text space used in Kbytes.
               %D  The average amount in (unshared) data/stack space used in Kbytes.
               %K  The total space used (%X + %D) in Kbytes.
               %M  The maximum memory the process had in use at any time in Kbytes.
               %F  The number of major page faults (page needed to be brought from disk).
               %R  The number of minor page faults.
               %I  The number of input operations.
               %O  The number of output operations.
               %r  The number of socket messages received.
               %s  The number of socket messages sent.
               %k  The number of signals received.
               %w  The number of voluntary context switches (waits).
               %c  The number of involuntary context switches.

               Only  the first four sequences are supported on systems without BSD resource limit functions.
               The default time format is `%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww' for systems  that  support
               resource usage reporting and `%Uu %Ss %E %P' for systems that do not.

               Under  Sequent's  DYNIX/ptx, %X, %D, %K, %r and %s are not available, but the following addi-
               tional sequences are:

               %Y  The number of system calls performed.
               %Z  The number of pages which are zero-filled on demand.
               %i  The number of times a process's resident set size was increased by the kernel.
               %d  The number of times a process's resident set size was decreased by the kernel.
               %l  The number of read system calls performed.
               %m  The number of write system calls performed.
               %p  The number of reads from raw disk devices.
               %q  The number of writes to raw disk devices.

               and the default time format is `%Uu %Ss %E %P %I+%Oio %Fpf+%Ww'.  Note that the CPU  percent-
               age can be higher than 100% on multi-processors.

       tperiod (+)
               The period, in minutes, between executions of the periodic special alias.

       tty (+) The name of the tty, or empty if not attached to one.

       uid (+) The user's real user ID.

       user    The user's login name.

       verbose If  set, causes the words of each command to be printed, after history substitution (if any).
               Set by the -v command line option.

       version (+)
               The version ID stamp.  It contains the shell's version number  (see  tcsh),  origin,  release
               date, vendor, operating system and machine (see VENDOR, OSTYPE and MACHTYPE) and a comma-sep-
               arated list of options which were set at compile time.  Options which are set by  default  in
               the distribution are noted.

               8b    The shell is eight bit clean; default
               7b    The shell is not eight bit clean
               wide  The shell is multibyte encoding clean (like UTF-8)
               nls   The system's NLS is used; default for systems with NLS
               lf    Login shells execute /etc/csh.login before instead of after /etc/csh.cshrc and ~/.login
                     before instead of after ~/.tcshrc and ~/.history.
               dl    `.' is put last in path for security; default
               nd    `.' is omitted from path for security
               vi    vi-style editing is the default rather than emacs
               dtr   Login shells drop DTR when exiting
               bye   bye is a synonym for logout and log is an alternate name for watchlog
               al    autologout is enabled; default
               kan   Kanji is used if appropriate according to locale settings,  unless  the  nokanji  shell
                     variable is set
               sm    The system's malloc(3) is used
               hb    The `#!<program> <args>' convention is emulated when executing shell scripts
               ng    The newgrp builtin is available
               rh    The shell attempts to set the REMOTEHOST environment variable
               afs   The  shell  verifies  your  password  with  the kerberos server if local authentication
                     fails.  The afsuser shell variable or the AFSUSER environment  variable  override  your
                     local username if set.

               An administrator may enter additional strings to indicate differences in the local version.

       visiblebell (+)
               If set, a screen flash is used rather than the audible bell.  See also nobeep.

       watch (+)
               A  list  of user/terminal pairs to watch for logins and logouts.  If either the user is `any'
               all terminals are watched for the given user and vice versa.  Setting watch  to  `(any  any)'
               watches all users and terminals.  For example,

                   set watch = (george ttyd1 any console $user any)

               reports  activity  of  the user `george' on ttyd1, any user on the console, and oneself (or a
               trespasser) on any terminal.

               Logins and logouts are checked every 10 minutes by default, but the first word of  watch  can
               be set to a number to check every so many minutes.  For example,

                   set watch = (1 any any)

               reports any login/logout once every minute.  For the impatient, the log builtin command trig-
               gers a watch report at any time.  All current logins are reported (as with the  log  builtin)
               when watch is first set.

               The who shell variable controls the format of watch reports.

       who (+) The  format  string  for  watch  messages.  The following sequences are replaced by the given

               %n  The name of the user who logged in/out.
               %a  The observed action, i.e., `logged on', `logged off' or `replaced olduser on'.
               %l  The terminal (tty) on which the user logged in/out.
               %M  The full hostname of the remote host, or `local' if the login/logout was from  the  local
               %m  The  hostname  of the remote host up to the first `.'.  The full name is printed if it is
                   an IP address or an X Window System display.

               %M and %m are available on only systems that store the  remote  hostname  in  /etc/utmp.   If
               unset,  `%n  has %a %l from %m.' is used, or `%n has %a %l.' on systems which don't store the
               remote hostname.

       wordchars (+)
               A list of non-alphanumeric characters to be considered part of a word  by  the  forward-word,
               backward-word etc., editor commands.  If unset, `*?_-.[]~=' is used.

       AFSUSER (+)
               Equivalent to the afsuser shell variable.

       COLUMNS The number of columns in the terminal.  See Terminal management.

       DISPLAY Used by X Window System (see X(1)).  If set, the shell does not set autologout (q.v.).

       EDITOR  The  pathname  to a default editor.  See also the VISUAL environment variable and the run-fg-
               editor editor command.

       GROUP (+)
               Equivalent to the group shell variable.

       HOME    Equivalent to the home shell variable.

       HOST (+)
               Initialized to the name of the machine on which the shell is running, as  determined  by  the
               gethostname(2) system call.

       HOSTTYPE (+)
               Initialized  to  the  type of machine on which the shell is running, as determined at compile
               time.  This variable is obsolete and will be removed in a future version.

       HPATH (+)
               A colon-separated list of directories in which the run-help editor command looks for  command

       LANG    Gives the preferred character environment.  See Native Language System support.

               If set, only ctype character handling is changed.  See Native Language System support.

       LINES   The number of lines in the terminal.  See Terminal management.

               The  format  of this variable is reminiscent of the termcap(5) file format; a colon-separated
               list of expressions of the form "xx=string", where "xx" is  a  two-character  variable  name.
               The variables with their associated defaults are:

                   no   0      Normal (non-filename) text
                   fi   0      Regular file
                   di   01;34  Directory
                   ln   01;36  Symbolic link
                   pi   33     Named pipe (FIFO)
                   so   01;35  Socket
                   do   01;35  Door
                   bd   01;33  Block device
                   cd   01;32  Character device
                   ex   01;32  Executable file
                   mi   (none) Missing file (defaults to fi)
                   or   (none) Orphaned symbolic link (defaults to ln)
                   lc   ^[[    Left code
                   rc   m      Right code
                   ec   (none) End code (replaces lc+no+rc)

               You need to include only the variables you want to change from the default.

               File  names  can  also  be  colorized  based on filename extension.  This is specified in the
               LS_COLORS variable using the syntax "*ext=string".  For example, using  ISO  6429  codes,  to
               color  all  C-language  source  files  blue you would specify "*.c=34".  This would color all
               files ending in .c in blue (34) color.

               Control characters can be written either in C-style-escaped notation, or in stty-like ^-nota-
               tion.   The  C-style  notation  adds ^[ for Escape, _ for a normal space character, and ? for
               Delete.  In addition, the ^[ escape character can be used to override the default interpreta-
               tion of ^[, ^, : and =.

               Each  file  will  be  written as <lc> <color-code> <rc> <filename> <ec>.  If the <ec> code is
               undefined, the sequence <lc> <no> <rc> will be used instead.  This is generally  more  conve-
               nient to use, but less general.  The left, right and end codes are provided so you don't have
               to type common parts over and over again and to support weird terminals; you  will  generally
               not need to change them at all unless your terminal does not use ISO 6429 color sequences but
               a different system.

               If your terminal does use ISO 6429 color codes, you can compose the  type  codes  (i.e.,  all
               except  the  lc, rc, and ec codes) from numerical commands separated by semicolons.  The most
               common commands are:

                       0   to restore default color
                       1   for brighter colors
                       4   for underlined text
                       5   for flashing text
                       30  for black foreground
                       31  for red foreground
                       32  for green foreground
                       33  for yellow (or brown) foreground
                       34  for blue foreground
                       35  for purple foreground
                       36  for cyan foreground
                       37  for white (or gray) foreground
                       40  for black background
                       41  for red background
                       42  for green background
                       43  for yellow (or brown) background
                       44  for blue background
                       45  for purple background
                       46  for cyan background
                       47  for white (or gray) background

               Not all commands will work on all systems or display devices.

               A few terminal programs do not recognize the default end code properly.   If  all  text  gets
               colorized  after  you  do a directory listing, try changing the no and fi codes from 0 to the
               numerical codes for your standard fore- and background colors.

       MACHTYPE (+)
               The machine type (microprocessor class or machine model), as determined at compile time.

       NOREBIND (+)
               If set, printable characters are not rebound to  self-insert-command.   See  Native  Language
               System support.

       OSTYPE (+)
               The operating system, as determined at compile time.

       PATH    A  colon-separated  list  of directories in which to look for executables.  Equivalent to the
               path shell variable, but in a different format.

       PWD (+) Equivalent to the cwd shell variable, but not synchronized  to  it;  updated  only  after  an
               actual directory change.

       REMOTEHOST (+)
               The  host  from  which  the user has logged in remotely, if this is the case and the shell is
               able to determine it.  Set only if the shell was so compiled; see the version shell variable.

       SHLVL (+)
               Equivalent to the shlvl shell variable.

       SYSTYPE (+)
               The current system type.  (Domain/OS only)

       TERM    Equivalent to the term shell variable.

       TERMCAP The terminal capability string.  See Terminal management.

       USER    Equivalent to the user shell variable.

       VENDOR (+)
               The vendor, as determined at compile time.

       VISUAL  The  pathname  to a default full-screen editor.  See also the EDITOR environment variable and
               the run-fg-editor editor command.

       /etc/csh.cshrc  Read first by every shell.  ConvexOS, Stellix and Intel use /etc/cshrc and NeXTs  use
                       /etc/cshrc.std.   A/UX,  AMIX,  Cray  and IRIX have no equivalent in csh(1), but read
                       this file in tcsh anyway.  Solaris 2.x does  not  have  it  either,  but  tcsh  reads
                       /etc/.cshrc.  (+)
       /etc/csh.login  Read  by  login  shells  after  /etc/csh.cshrc.   ConvexOS,  Stellix  and  Intel  use
                       /etc/login, NeXTs use /etc/login.std, Solaris 2.x uses /etc/.login  and  A/UX,  AMIX,
                       Cray and IRIX use /etc/cshrc.
       ~/.tcshrc (+)   Read by every shell after /etc/csh.cshrc or its equivalent.
       ~/.cshrc        Read  by every shell, if ~/.tcshrc doesn't exist, after /etc/csh.cshrc or its equiva-
                       lent.  This manual uses `~/.tcshrc' to mean `~/.tcshrc or, if ~/.tcshrc is not found,
       ~/.history      Read by login shells after ~/.tcshrc if savehist is set, but see also histfile.
       ~/.login        Read  by  login  shells  after ~/.tcshrc or ~/.history.  The shell may be compiled to
                       read ~/.login before instead of after ~/.tcshrc and ~/.history; see the version shell
       ~/.cshdirs (+)  Read by login shells after ~/.login if savedirs is set, but see also dirsfile.
       /etc/csh.logout Read  by  login  shells  at  logout.  ConvexOS, Stellix and Intel use /etc/logout and
                       NeXTs use /etc/logout.std.  A/UX, AMIX, Cray and IRIX have no equivalent  in  csh(1),
                       but  read  this  file  in tcsh anyway.  Solaris 2.x does not have it either, but tcsh
                       reads /etc/.logout.  (+)
       ~/.logout       Read by login shells at logout after /etc/csh.logout or its equivalent.
       /bin/sh         Used to interpret shell scripts not starting with a `#'.
       /tmp/sh*        Temporary file for `<<'.
       /etc/passwd     Source of home directories for `~name' substitutions.

       The order in which startup files are read may differ if the shell was so compiled;  see  Startup  and
       shutdown and the version shell variable.

       This  manual describes tcsh as a single entity, but experienced csh(1) users will want to pay special
       attention to tcsh's new features.

       A command-line editor, which supports GNU Emacs or vi(1)-style key bindings.   See  The  command-line
       editor and Editor commands.

       Programmable,  interactive  word completion and listing.  See Completion and listing and the complete
       and uncomplete builtin commands.

       Spelling correction (q.v.) of filenames, commands and variables.

       Editor commands (q.v.) which perform other useful functions in the middle of typed commands,  includ-
       ing  documentation  lookup (run-help), quick editor restarting (run-fg-editor) and command resolution

       An enhanced history mechanism.  Events in the history list are time-stamped.  See  also  the  history
       command  and  its associated shell variables, the previously undocumented `#' event specifier and new
       modifiers under History substitution, the *-history, history-search-*,  i-search-*,  vi-search-*  and
       toggle-literal-history editor commands and the histlit shell variable.

       Enhanced  directory  parsing and directory stack handling.  See the cd, pushd, popd and dirs commands
       and their associated shell variables, the description of Directory stack substitution, the  dirstack,
       owd and symlinks shell variables and the normalize-command and normalize-path editor commands.

       Negation in glob-patterns.  See Filename substitution.

       New File inquiry operators (q.v.) and a filetest builtin which uses them.

       A variety of Automatic, periodic and timed events (q.v.) including scheduled events, special aliases,
       automatic logout and terminal locking, command timing and watching for logins and logouts.

       Support for the Native Language System (see Native Language System support), OS variant features (see
       OS  variant  support  and  the  echo_style  shell  variable) and system-dependent file locations (see

       Extensive terminal-management capabilities.  See Terminal management.

       New builtin commands including builtins, hup, ls-F, newgrp, printenv, which and where (q.v.).

       New variables that make useful information easily available to the shell.  See the gid, loginsh, oid,
       shlvl,  tcsh,  tty,  uid  and  version  shell  variables and the HOST, REMOTEHOST, VENDOR, OSTYPE and
       MACHTYPE environment variables.

       A new syntax for including useful information in the prompt string (see prompt).  and special prompts
       for loops and spelling correction (see prompt2 and prompt3).

       Read-only variables.  See Variable substitution.

       When  a  suspended command is restarted, the shell prints the directory it started in if this is dif-
       ferent from the current directory.  This can be misleading (i.e., wrong) as the job may have  changed
       directories internally.

       Shell builtin functions are not stoppable/restartable.  Command sequences of the form `a ; b ; c' are
       also not handled gracefully when stopping is attempted.  If you suspend  `b',  the  shell  will  then
       immediately  execute `c'.  This is especially noticeable if this expansion results from an alias.  It
       suffices to place the sequence of commands in ()'s to force it to a subshell, i.e., `( a ; b ; c  )'.

       Control  over  tty output after processes are started is primitive; perhaps this will inspire someone
       to work on a good virtual terminal interface.  In a virtual terminal interface much more  interesting
       things could be done with output control.

       Alias  substitution is most often used to clumsily simulate shell procedures; shell procedures should
       be provided rather than aliases.

       Commands within loops are not placed in the history list.  Control structures should be parsed rather
       than being recognized as built-in commands.  This would allow control commands to be placed anywhere,
       to be combined with `|', and to be used with `&' and `;' metasyntax.

       foreach doesn't ignore here documents when looking for its end.

       It should be possible to use the `:' modifiers on the output of command substitutions.

       The screen update for lines longer than the screen width is very poor if the terminal cannot move the
       cursor up (i.e., terminal type `dumb').

       HPATH and NOREBIND don't need to be environment variables.

       Glob-patterns which do not use `?', `*' or `[]' or which use `{}' or `~' are not negated correctly.

       The single-command form of if does output redirection even if the expression is false and the command
       is not executed.

       ls-F includes file identification characters when sorting filenames and does not handle control char-
       acters in filenames well.  It cannot be interrupted.

       Command substitution supports multiple commands and conditions, but not cycles or backward gotos.

       Report  bugs  at  preferably with fixes.  If you want to help maintain and test
       tcsh, send mail to with the text `subscribe tcsh' on a line by itself  in  the

       In 1964, DEC produced the PDP-6.  The PDP-10 was a later re-implementation.  It was re-christened the
       DECsystem-10 in 1970 or so when DEC brought out the second model, the KI10.

       TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts think tank)  in  1972  as  an
       experiment  in  demand-paged  virtual  memory  operating systems.  They built a new pager for the DEC
       PDP-10 and created the OS to go with it.  It was extremely successful in academia.

       In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to have only a version of
       TENEX,  which  they had licensed from BBN, for the new box.  They called their version TOPS-20 (their
       capitalization is trademarked).  A lot of TOPS-10 users (`The OPerating System for PDP-10') objected;
       thus  DEC  found  themselves supporting two incompatible systems on the same hardware--but then there
       were 6 on the PDP-11!

       TENEX, and TOPS-20 to version 3, had command completion  via  a  user-code-level  subroutine  library
       called ULTCMD.  With version 3, DEC moved all that capability and more into the monitor (`kernel' for
       you Unix types), accessed by the COMND% JSYS (`Jump to SYStem' instruction, the supervisor call mech-
       anism [are my IBM roots also showing?]).

       The  creator  of tcsh was impressed by this feature and several others of TENEX and TOPS-20, and cre-
       ated a version of csh which mimicked them.

       Words can be no longer than 1024 characters.

       The system limits argument lists to 10240 characters.

       The number of arguments to a command which involves filename expansion is limited to 1/6th the number
       of characters allowed in an argument list.

       Command substitutions may substitute no more characters than are allowed in an argument list.

       To detect looping, the shell restricts the number of alias substitutions on a single line to 20.

       csh(1),  emacs(1),  ls(1),  newgrp(1),  sh(1),  setpath(1),  stty(1),  su(1),  tset(1),  vi(1), x(1),
       access(2), execve(2),  fork(2),  killpg(2),  pipe(2),  setrlimit(2),  sigvec(2),  stat(2),  umask(2),
       vfork(2),  wait(2),  malloc(3),  setlocale(3),  tty(4),  a.out(5), termcap(5), environ(7), termio(7),
       Introduction to the C Shell

       This manual documents tcsh 6.14.00 (Astron) 2005-03-25.

       William Joy
         Original author of csh(1)
       J.E. Kulp, IIASA, Laxenburg, Austria
         Job control and directory stack features
       Ken Greer, HP Labs, 1981
         File name completion
       Mike Ellis, Fairchild, 1983
         Command name recognition/completion
       Paul Placeway, Ohio State CIS Dept., 1983-1993
         Command line editor, prompt routines, new glob syntax and numerous fixes and speedups
       Karl Kleinpaste, CCI 1983-4
         Special aliases, directory stack extraction stuff, login/logout watch, scheduled  events,  and  the
         idea of the new prompt format
       Rayan Zachariassen, University of Toronto, 1984
         ls-F and which builtins and numerous bug fixes, modifications and speedups
       Chris Kingsley, Caltech
         Fast storage allocator routines
       Chris Grevstad, TRW, 1987
         Incorporated 4.3BSD csh into tcsh
       Christos S. Zoulas, Cornell U. EE Dept., 1987-94
         Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS support and a new version of
       James J Dempsey, BBN, and Paul Placeway, OSU, 1988
         A/UX port
       Daniel Long, NNSC, 1988
       Patrick Wolfe, Kuck and Associates, Inc., 1988
         vi mode cleanup
       David C Lawrence, Rensselaer Polytechnic Institute, 1989
         autolist and ambiguous completion listing
       Alec Wolman, DEC, 1989
         Newlines in the prompt
       Matt Landau, BBN, 1989
       Ray Moody, Purdue Physics, 1989
         Magic space bar history expansion
       Mordechai ????, Intel, 1989
         printprompt() fixes and additions
       Kazuhiro Honda, Dept. of Computer Science, Keio University, 1989
         Automatic spelling correction and prompt3
       Per Hedeland, Ellemtel, Sweden, 1990-
         Various bugfixes, improvements and manual updates
       Hans J. Albertsson (Sun Sweden)
         ampm, settc and telltc
       Michael Bloom
         Interrupt handling fixes
       Michael Fine, Digital Equipment Corp
         Extended key support
       Eric Schnoebelen, Convex, 1990
         Convex support, lots of csh bug fixes, save and restore of directory stack
       Ron Flax, Apple, 1990
         A/UX 2.0 (re)port
       Dan Oscarsson, LTH Sweden, 1990
         NLS support and simulated NLS support for non NLS sites, fixes
       Johan Widen, SICS Sweden, 1990
         shlvl, Mach support, correct-line, 8-bit printing
       Matt Day, Sanyo Icon, 1990
         POSIX termio support, SysV limit fixes
       Jaap Vermeulen, Sequent, 1990-91
         Vi mode fixes, expand-line, window change fixes, Symmetry port
       Martin Boyer, Institut de recherche d'Hydro-Quebec, 1991
         autolist beeping options, modified the history search to search  for  the  whole  string  from  the
         beginning of the line to the cursor.
       Scott Krotz, Motorola, 1991
         Minix port
       David Dawes, Sydney U. Australia, Physics Dept., 1991
         SVR4 job control fixes
       Jose Sousa, Interactive Systems Corp., 1991
         Extended vi fixes and vi delete command
       Marc Horowitz, MIT, 1991
         ANSIfication fixes, new exec hashing code, imake fixes, where
       Bruce Sterling Woodcock,, 1991-1995
         ETA  and Pyramid port, Makefile and lint fixes, ignoreeof=n addition, and various other portability
         changes and bug fixes
       Jeff Fink, 1992
         complete-word-fwd and complete-word-back
       Harry C. Pulley, 1992
         Coherent port
       Andy Phillips, Mullard Space Science Lab U.K., 1992
         VMS-POSIX port
       Beto Appleton, IBM Corp., 1992
         Walking process group fixes, csh bug fixes, POSIX file tests, POSIX SIGHUP
       Scott Bolte, Cray Computer Corp., 1992
         CSOS port
       Kaveh R. Ghazi, Rutgers University, 1992
         Tek, m88k, Titan and Masscomp ports and fixes.  Added autoconf support.
       Mark Linderman, Cornell University, 1992
         OS/2 port
       Mika Liljeberg, liljeber@kruuna.Helsinki.FI, 1992
         Linux port
       Tim P. Starrin, NASA Langley Research Center Operations, 1993
         Read-only variables
       Dave Schweisguth, Yale University, 1993-4
         New man page and tcsh.man2html
       Larry Schwimmer, Stanford University, 1993
         AFS and HESIOD patches
       Luke Mewburn, RMIT University, 1994-6
         Enhanced directory printing in prompt, added ellipsis and rprompt.
       Edward Hutchins, Silicon Graphics Inc., 1996
         Added implicit cd.
       Martin Kraemer, 1997
         Ported to Siemens Nixdorf EBCDIC machine
       Amol Deshpande, Microsoft, 1997
         Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing library and message catalog code
         to interface to Windows.
       Taga Nayuta, 1998
         Color ls additions.

       Bryan  Dunlap,  Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana Smetters, Bob Sutter-
       field, Mark Verber, Elizabeth Zwicky and all the other people  at  Ohio  State  for  suggestions  and

       All  the  people  on the net, for putting up with, reporting bugs in, and suggesting new additions to
       each and every version

       Richard M. Alderson III, for writing the `T in tcsh' section

Astron 6.14.00                                  25 March 2005                                        TCSH(1)

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