LESS(1) LESS(1)
NAME
less - opposite of more
SYNOPSIS
less -?
less --help
less -V
less --version
less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[-# shift] [+[+]cmd] [--] [filename]...
(See the OPTIONS section for alternate option syntax with long option names.)
DESCRIPTION
Less is a program similar to more (1), but which allows backward movement in the file as well as for-ward forward
ward movement. Also, less does not have to read the entire input file before starting, so with large
input files it starts up faster than text editors like vi (1). Less uses termcap (or terminfo on
some systems), so it can run on a variety of terminals. There is even limited support for hardcopy
terminals. (On a hardcopy terminal, lines which should be printed at the top of the screen are pre-fixed prefixed
fixed with a caret.)
Commands are based on both more and vi. Commands may be preceded by a decimal number, called N in
the descriptions below. The number is used by some commands, as indicated.
COMMANDS
In the following descriptions, ^X means control-X. ESC stands for the ESCAPE key; for example ESC-v
means the two character sequence "ESCAPE", then "v".
h or H Help: display a summary of these commands. If you forget all the other commands, remember
this one.
SPACE or ^V or f or ^F
Scroll forward N lines, default one window (see option -z below). If N is more than the
screen size, only the final screenful is displayed. Warning: some systems use ^V as a special
literalization character.
z Like SPACE, but if N is specified, it becomes the new window size.
ESC-SPACE
Like SPACE, but scrolls a full screenful, even if it reaches end-of-file in the process.
RETURN or ^N or e or ^E or j or ^J
Scroll forward N lines, default 1. The entire N lines are displayed, even if N is more than
the screen size.
d or ^D
Scroll forward N lines, default one half of the screen size. If N is specified, it becomes
the new default for subsequent d and u commands.
b or ^B or ESC-v
Scroll backward N lines, default one window (see option -z below). If N is more than the
screen size, only the final screenful is displayed.
w Like ESC-v, but if N is specified, it becomes the new window size.
y or ^Y or ^P or k or ^K
Scroll backward N lines, default 1. The entire N lines are displayed, even if N is more than
the screen size. Warning: some systems use ^Y as a special job control character.
u or ^U
Scroll backward N lines, default one half of the screen size. If N is specified, it becomes
the new default for subsequent d and u commands.
ESC-) or RIGHTARROW
Scroll horizontally right N characters, default half the screen width (see the -# option). If
a number N is specified, it becomes the default for future RIGHTARROW and LEFTARROW commands.
While the text is scrolled, it acts as though the -S option (chop lines) were in effect.
ESC-( or LEFTARROW
Scroll horizontally left N characters, default half the screen width (see the -# option). If
a number N is specified, it becomes the default for future RIGHTARROW and LEFTARROW commands.
r or ^R or ^L
Repaint the screen.
R Repaint the screen, discarding any buffered input. Useful if the file is changing while it is
being viewed.
F Scroll forward, and keep trying to read when the end of file is reached. Normally this com-mand command
mand would be used when already at the end of the file. It is a way to monitor the tail of a
file which is growing while it is being viewed. (The behavior is similar to the "tail -f"
command.)
g or < or ESC-<
Go to line N in the file, default 1 (beginning of file). (Warning: this may be slow if N is
large.)
G or > or ESC->
Go to line N in the file, default the end of the file. (Warning: this may be slow if N is
large, or if N is not specified and standard input, rather than a file, is being read.)
p or % Go to a position N percent into the file. N should be between 0 and 100.
{ If a left curly bracket appears in the top line displayed on the screen, the { command will go
to the matching right curly bracket. The matching right curly bracket is positioned on the
bottom line of the screen. If there is more than one left curly bracket on the top line, a
number N may be used to specify the N-th bracket on the line.
} If a right curly bracket appears in the bottom line displayed on the screen, the } command
will go to the matching left curly bracket. The matching left curly bracket is positioned on
the top line of the screen. If there is more than one right curly bracket on the top line, a
number N may be used to specify the N-th bracket on the line.
( Like {, but applies to parentheses rather than curly brackets.
) Like }, but applies to parentheses rather than curly brackets.
[ Like {, but applies to square brackets rather than curly brackets.
] Like }, but applies to square brackets rather than curly brackets.
ESC-^F Followed by two characters, acts like {, but uses the two characters as open and close brack-ets, brackets,
ets, respectively. For example, "ESC ^F < >" could be used to go forward to the > which
matches the < in the top displayed line.
ESC-^B Followed by two characters, acts like }, but uses the two characters as open and close brack-
ets, respectively. For example, "ESC ^B < >" could be used to go backward to the < which
matches the > in the bottom displayed line.
m Followed by any lowercase letter, marks the current position with that letter.
' (Single quote.) Followed by any lowercase letter, returns to the position which was previ-ously previously
ously marked with that letter. Followed by another single quote, returns to the position at
which the last "large" movement command was executed. Followed by a ^ or $, jumps to the
beginning or end of the file respectively. Marks are preserved when a new file is examined,
so the ' command can be used to switch between input files.
^X^X Same as single quote.
/pattern
Search forward in the file for the N-th line containing the pattern. N defaults to 1. The
pattern is a regular expression, as recognized by the regular expression library supplied by
your system. The search starts at the second line displayed (but see the -a and -j options,
which change this).
Certain characters are special if entered at the beginning of the pattern; they modify the
type of search rather than become part of the pattern:
^N or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search reaches the END of the current file
without finding a match, the search continues in the next file in the command line
list.
^F or @
Begin the search at the first line of the FIRST file in the command line list, regard-less regardless
less of what is currently displayed on the screen or the settings of the -a or -j
options.
^K Highlight any text which matches the pattern on the current screen, but don't move to
the first match (KEEP current position).
^R Don't interpret regular expression metacharacters; that is, do a simple textual compar-ison. comparison.
ison.
?pattern
Search backward in the file for the N-th line containing the pattern. The search starts at
the line immediately before the top line displayed.
Certain characters are special as in the / command:
^N or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search reaches the beginning of the current
file without finding a match, the search continues in the previous file in the command
line list.
^F or @
Begin the search at the last line of the last file in the command line list, regardless
of what is currently displayed on the screen or the settings of the -a or -j options.
^K As in forward searches.
^R As in forward searches.
ESC-/pattern
Same as "/*".
ESC-?pattern
Same as "?*".
n Repeat previous search, for N-th line containing the last pattern. If the previous search was
modified by ^N, the search is made for the N-th line NOT containing the pattern. If the pre-vious previous
vious search was modified by ^E, the search continues in the next (or previous) file if not
satisfied in the current file. If the previous search was modified by ^R, the search is done
without using regular expressions. There is no effect if the previous search was modified by
^F or ^K.
N Repeat previous search, but in the reverse direction.
ESC-n Repeat previous search, but crossing file boundaries. The effect is as if the previous search
were modified by *.
ESC-N Repeat previous search, but in the reverse direction and crossing file boundaries.
ESC-u Undo search highlighting. Turn off highlighting of strings matching the current search pat-tern. pattern.
tern. If highlighting is already off because of a previous ESC-u command, turn highlighting
back on. Any search command will also turn highlighting back on. (Highlighting can also be
disabled by toggling the -G option; in that case search commands do not turn highlighting back
on.)
:e [filename]
Examine a new file. If the filename is missing, the "current" file (see the :n and :p com-mands commands
mands below) from the list of files in the command line is re-examined. A percent sign (%) in
the filename is replaced by the name of the current file. A pound sign (#) is replaced by the
name of the previously examined file. However, two consecutive percent signs are simply
replaced with a single percent sign. This allows you to enter a filename that contains a per-cent percent
cent sign in the name. Similarly, two consecutive pound signs are replaced with a single
pound sign. The filename is inserted into the command line list of files so that it can be
seen by subsequent :n and :p commands. If the filename consists of several files, they are
all inserted into the list of files and the first one is examined. If the filename contains
one or more spaces, the entire filename should be enclosed in double quotes (also see the -"
option).
^X^V or E
Same as :e. Warning: some systems use ^V as a special literalization character. On such sys-tems, systems,
tems, you may not be able to use ^V.
:n Examine the next file (from the list of files given in the command line). If a number N is
specified, the N-th next file is examined.
:p Examine the previous file in the command line list. If a number N is specified, the N-th pre-vious previous
vious file is examined.
:x Examine the first file in the command line list. If a number N is specified, the N-th file in
the list is examined.
:d Remove the current file from the list of files.
t Go to the next tag, if there were more than one matches for the current tag. See the -t
option for more details about tags.
T Go to the previous tag, if there were more than one matches for the current tag.
= or ^G or :f
Prints some information about the file being viewed, including its name and the line number
and byte offset of the bottom line being displayed. If possible, it also prints the length of
the file, the number of lines in the file and the percent of the file above the last displayed
line.
- Followed by one of the command line option letters (see OPTIONS below), this will change the
setting of that option and print a message describing the new setting. If a ^P (CONTROL-P) is
entered immediately after the dash, the setting of the option is changed but no message is
printed. If the option letter has a numeric value (such as -b or -h), or a string value (such
as -P or -t), a new value may be entered after the option letter. If no new value is entered,
a message describing the current setting is printed and nothing is changed.
-- Like the - command, but takes a long option name (see OPTIONS below) rather than a single
option letter. You must press RETURN after typing the option name. A ^P immediately after
the second dash suppresses printing of a message describing the new setting, as in the - com-mand. command.
mand.
-+ Followed by one of the command line option letters this will reset the option to its default
setting and print a message describing the new setting. (The "-+X" command does the same
thing as "-+X" on the command line.) This does not work for string-valued options.
--+ Like the -+ command, but takes a long option name rather than a single option letter.
-! Followed by one of the command line option letters, this will reset the option to the "oppo-site" "opposite"
site" of its default setting and print a message describing the new setting. This does not
work for numeric or string-valued options.
--! Like the -! command, but takes a long option name rather than a single option letter.
_ (Underscore.) Followed by one of the command line option letters, this will print a message
describing the current setting of that option. The setting of the option is not changed.
__ (Double underscore.) Like the _ (underscore) command, but takes a long option name rather
than a single option letter. You must press RETURN after typing the option name.
+cmd Causes the specified cmd to be executed each time a new file is examined. For example, +G
causes less to initially display each file starting at the end rather than the beginning.
V Prints the version number of less being run.
q or Q or :q or :Q or ZZ
Exits less.
The following four commands may or may not be valid, depending on your particular installation.
v Invokes an editor to edit the current file being viewed. The editor is taken from the envi-ronment environment
ronment variable VISUAL if defined, or EDITOR if VISUAL is not defined, or defaults to "vi" if
neither VISUAL nor EDITOR is defined. See also the discussion of LESSEDIT under the section
on PROMPTS below.
! shell-command
Invokes a shell to run the shell-command given. A percent sign (%) in the command is replaced
by the name of the current file. A pound sign (#) is replaced by the name of the previously
examined file. "!!" repeats the last shell command. "!" with no shell command simply invokes
a shell. On Unix systems, the shell is taken from the environment variable SHELL, or defaults
to "sh". On MS-DOS and OS/2 systems, the shell is the normal command processor.
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input file to the given shell command.
The section of the file to be piped is between the first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to indicate beginning or end of file
respectively. If <m> is . or newline, the current screen is piped.
s filename
Save the input to a file. This only works if the input is a pipe, not an ordinary file.
OPTIONS
Command line options are described below. Most options may be changed while less is running, via the
"-" command.
Most options may be given in one of two forms: either a dash followed by a single letter, or two
dashes followed by a long option name. A long option name may be abbreviated as long as the abbrevi-ation abbreviation
ation is unambiguous. For example, --quit-at-eof may be abbreviated --quit, but not --qui, since
both --quit-at-eof and --quiet begin with --qui. Some long option names are in uppercase, such as
--QUIT-AT-EOF, as distinct from --quit-at-eof. Such option names need only have their first letter
capitalized; the remainder of the name may be in either case. For example, --Quit-at-eof is equiva-lent equivalent
lent to --QUIT-AT-EOF.
Options are also taken from the environment variable "LESS". For example, to avoid typing "less
-options ..." each time less is invoked, you might tell csh:
setenv LESS "-options"
or if you use sh:
LESS="-options"; export LESS
On MS-DOS, you don't need the quotes, but you should replace any percent signs in the options string
by double percent signs.
The environment variable is parsed before the command line, so command line options override the LESS
environment variable. If an option appears in the LESS variable, it can be reset to its default
value on the command line by beginning the command line option with "-+".
For options like -P or -D which take a following string, a dollar sign ($) must be used to signal the
end of the string. For example, to set two -D options on MS-DOS, you must have a dollar sign between
them, like this:
LESS="-Dn9.1$-Ds4.1"
-? or --help
This option displays a summary of the commands accepted by less (the same as the h command).
(Depending on how your shell interprets the question mark, it may be necessary to quote the
question mark, thus: "-\?".)
-a or --search-skip-screen
Causes searches to start after the last line displayed on the screen, thus skipping all lines
displayed on the screen. By default, searches start at the second line on the screen (or
after the last found line; see the -j option).
-bn or --buffers=n
Specifies the amount of buffer space less will use for each file, in units of kilobytes (1024
bytes). By default 64K of buffer space is used for each file (unless the file is a pipe; see
the -B option). The -b option specifies instead that n kilobytes of buffer space should be
used for each file. If n is -1, buffer space is unlimited; that is, the entire file is read
into memory.
-B or --auto-buffers
By default, when data is read from a pipe, buffers are allocated automatically as needed. If
a large amount of data is read from the pipe, this can cause a large amount of memory to be
allocated. The -B option disables this automatic allocation of buffers for pipes, so that
only 64K (or the amount of space specified by the -b option) is used for the pipe. Warning:
use of -B can result in erroneous display, since only the most recently viewed part of the
file is kept in memory; any earlier data is lost.
-c or --clear-screen
Causes full screen repaints to be painted from the top line down. By default, full screen
repaints are done by scrolling from the bottom of the screen.
-C or --CLEAR-SCREEN
The -C option is like -c, but the screen is cleared before it is repainted.
-d or --dumb
The -d option suppresses the error message normally displayed if the terminal is dumb; that
is, lacks some important capability, such as the ability to clear the screen or scroll back-ward. backward.
ward. The -d option does not otherwise change the behavior of less on a dumb terminal.
-Dxcolor or --color=xcolor
[MS-DOS only] Sets the color of the text displayed. x is a single character which selects the
type of text whose color is being set: n=normal, s=standout, d=bold, u=underlined, k=blink.
color is a pair of numbers separated by a period. The first number selects the foreground
color and the second selects the background color of the text. A single number N is the same
as N.0.
-e or --quit-at-eof
Causes less to automatically exit the second time it reaches end-of-file. By default, the
only way to exit less is via the "q" command.
-E or --QUIT-AT-EOF
Causes less to automatically exit the first time it reaches end-of-file.
-f or --force
Forces non-regular files to be opened. (A non-regular file is a directory or a device special
file.) Also suppresses the warning message when a binary file is opened. By default, less
will refuse to open non-regular files.
-F or --quit-if-one-screen
Causes less to automatically exit if the entire file can be displayed on the first screen.
-g or --hilite-search
Normally, less will highlight ALL strings which match the last search command. The -g option
changes this behavior to highlight only the particular string which was found by the last
search command. This can cause less to run somewhat faster than the default.
-G or --HILITE-SEARCH
The -G option suppresses all highlighting of strings found by search commands.
-hn or --max-back-scroll=n
Specifies a maximum number of lines to scroll backward. If it is necessary to scroll backward
more than n lines, the screen is repainted in a forward direction instead. (If the terminal
does not have the ability to scroll backward, -h0 is implied.)
-i or --ignore-case
Causes searches to ignore case; that is, uppercase and lowercase are considered identical.
This option is ignored if any uppercase letters appear in the search pattern; in other words,
if a pattern contains uppercase letters, then that search does not ignore case.
-I or --IGNORE-CASE
Like -i, but searches ignore case even if the pattern contains uppercase letters.
-jn or --jump-target=n
Specifies a line on the screen where the "target" line is to be positioned. A target line is
the object of a text search, tag search, jump to a line number, jump to a file percentage, or
jump to a marked position. The screen line is specified by a number: the top line on the
screen is 1, the next is 2, and so on. The number may be negative to specify a line relative
to the bottom of the screen: the bottom line on the screen is -1, the second to the bottom is
-2, and so on. If the -j option is used, searches begin at the line immediately after the
target line. For example, if "-j4" is used, the target line is the fourth line on the screen,
so searches begin at the fifth line on the screen.
-J or --status-column
Displays a status column at the left edge of the screen. The status column shows the lines
that matched the current search. The status column is also used if the -w or -W option is in
effect.
-kfilename or --lesskey-file=filename
Causes less to open and interpret the named file as a lesskey (1) file. Multiple -k options
may be specified. If the LESSKEY or LESSKEY_SYSTEM environment variable is set, or if a
lesskey file is found in a standard place (see KEY BINDINGS), it is also used as a lesskey
file.
-K or --quit-on-intr
Causes less to exit immediately when an interrupt character (usually ^C) is typed. Normally,
an interrupt character causes less to stop whatever it is doing and return to its command
prompt.
-L or --no-lessopen
Ignore the LESSOPEN environment variable (see the INPUT PREPROCESSOR section below). This
option can be set from within less, but it will apply only to files opened subsequently, not
to the file which is currently open.
-m or --long-prompt
Causes less to prompt verbosely (like more), with the percent into the file. By default, less
prompts with a colon.
-M or --LONG-PROMPT
Causes less to prompt even more verbosely than more.
-n or --line-numbers
Suppresses line numbers. The default (to use line numbers) may cause less to run more slowly
in some cases, especially with a very large input file. Suppressing line numbers with the -n
option will avoid this problem. Using line numbers means: the line number will be displayed
in the verbose prompt and in the = command, and the v command will pass the current line num-ber number
ber to the editor (see also the discussion of LESSEDIT in PROMPTS below).
-N or --LINE-NUMBERS
Causes a line number to be displayed at the beginning of each line in the display.
-ofilename or --log-file=filename
Causes less to copy its input to the named file as it is being viewed. This applies only when
the input file is a pipe, not an ordinary file. If the file already exists, less will ask for
confirmation before overwriting it.
-Ofilename or --LOG-FILE=filename
The -O option is like -o, but it will overwrite an existing file without asking for confirma-tion. confirmation.
tion.
If no log file has been specified, the -o and -O options can be used from within less to spec-ify specify
ify a log file. Without a file name, they will simply report the name of the log file. The
"s" command is equivalent to specifying -o from within less.
-ppattern or --pattern=pattern
The -p option on the command line is equivalent to specifying +/pattern; that is, it tells
less to start at the first occurrence of pattern in the file.
-Pprompt or --prompt=prompt
Provides a way to tailor the three prompt styles to your own preference. This option would
normally be put in the LESS environment variable, rather than being typed in with each less
command. Such an option must either be the last option in the LESS variable, or be terminated
by a dollar sign. -Ps followed by a string changes the default (short) prompt to that string.
-Pm changes the medium (-m) prompt. -PM changes the long (-M) prompt. -Ph changes the prompt
for the help screen. -P= changes the message printed by the = command. -Pw changes the mes-sage message
sage printed while waiting for data (in the F command). All prompt strings consist of a
sequence of letters and special escape sequences. See the section on PROMPTS for more
details.
-q or --quiet or --silent
Causes moderately "quiet" operation: the terminal bell is not rung if an attempt is made to
scroll past the end of the file or before the beginning of the file. If the terminal has a
"visual bell", it is used instead. The bell will be rung on certain other errors, such as
typing an invalid character. The default is to ring the terminal bell in all such cases.
-Q or --QUIET or --SILENT
Causes totally "quiet" operation: the terminal bell is never rung.
-r or --raw-control-chars
Causes "raw" control characters to be displayed. The default is to display control characters
using the caret notation; for example, a control-A (octal 001) is displayed as "^A". Warning:
when the -r option is used, less cannot keep track of the actual appearance of the screen
(since this depends on how the screen responds to each type of control character). Thus, var-ious various
ious display problems may result, such as long lines being split in the wrong place.
-R or --RAW-CONTROL-CHARS
Like -r, but only ANSI "color" escape sequences are output in "raw" form. Unlike -r, the
screen appearance is maintained correctly in most cases. ANSI "color" escape sequences are
sequences of the form:
ESC [ ... m
where the "..." is zero or more color specification characters For the purpose of keeping
track of screen appearance, ANSI color escape sequences are assumed to not move the cursor.
You can make less think that characters other than "m" can end ANSI color escape sequences by
setting the environment variable LESSANSIENDCHARS to the list of characters which can end a
color escape sequence. And you can make less think that characters other than the standard
ones may appear between the ESC and the m by setting the environment variable LESSANSIMIDCHARS
to the list of characters which can appear.
-s or --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a single blank line. This is useful when
viewing nroff output.
-S or --chop-long-lines
Causes lines longer than the screen width to be chopped rather than folded. That is, the por-tion portion
tion of a long line that does not fit in the screen width is not shown. The default is to
fold long lines; that is, display the remainder on the next line.
-ttag or --tag=tag
The -t option, followed immediately by a TAG, will edit the file containing that tag. For
this to work, tag information must be available; for example, there may be a file in the cur-rent current
rent directory called "tags", which was previously built by ctags (1) or an equivalent com-mand. command.
mand. If the environment variable LESSGLOBALTAGS is set, it is taken to be the name of a com-mand command
mand compatible with global (1), and that command is executed to find the tag. (See
http://www.gnu.org/software/global/global.html) The -t option may also be specified from
within less (using the - command) as a way of examining a new file. The command ":t" is
equivalent to specifying -t from within less.
-Ttagsfile or --tag-file=tagsfile
Specifies a tags file to be used instead of "tags".
-u or --underline-special
Causes backspaces and carriage returns to be treated as printable characters; that is, they
are sent to the terminal when they appear in the input.
-U or --UNDERLINE-SPECIAL
Causes backspaces, tabs and carriage returns to be treated as control characters; that is,
they are handled as specified by the -r option.
By default, if neither -u nor -U is given, backspaces which appear adjacent to an underscore
character are treated specially: the underlined text is displayed using the terminal's hard-
ware underlining capability. Also, backspaces which appear between two identical characters
are treated specially: the overstruck text is printed using the terminal's hardware boldface
capability. Other backspaces are deleted, along with the preceding character. Carriage
returns immediately followed by a newline are deleted. other carriage returns are handled as
specified by the -r option. Text which is overstruck or underlined can be searched for if
neither -u nor -U is in effect.
-V or --version
Displays the version number of less.
-w or --hilite-unread
Temporarily highlights the first "new" line after a forward movement of a full page. The
first "new" line is the line immediately following the line previously at the bottom of the
screen. Also highlights the target line after a g or p command. The highlight is removed at
the next command which causes movement. The entire line is highlighted, unless the -J option
is in effect, in which case only the status column is highlighted.
-W or --HILITE-UNREAD
Like -w, but temporarily highlights the first new line after any forward movement command
larger than one line.
-xn,... or --tabs=n,...
Sets tab stops. If only one n is specified, tab stops are set at multiples of n. If multiple
values separated by commas are specified, tab stops are set at those positions, and then con-
tinue with the same spacing as the last two. For example, -x9,17 will set tabs at positions
9, 17, 25, 33, etc. The default for n is 8.
-X or --no-init
Disables sending the termcap initialization and deinitialization strings to the terminal.
This is sometimes desirable if the deinitialization string does something unnecessary, like
clearing the screen.
--no-keypad
Disables sending the keypad initialization and deinitialization strings to the terminal. This
is sometimes useful if the keypad strings make the numeric keypad behave in an undesirable
manner.
-yn or --max-forw-scroll=n
Specifies a maximum number of lines to scroll forward. If it is necessary to scroll forward
more than n lines, the screen is repainted instead. The -c or -C option may be used to
repaint from the top of the screen if desired. By default, any forward movement causes
scrolling.
-[z]n or --window=n
Changes the default scrolling window size to n lines. The default is one screenful. The z
and w commands can also be used to change the window size. The "z" may be omitted for compat-
ibility with more. If the number n is negative, it indicates n lines less than the current
screen size. For example, if the screen is 24 lines, -z-4 sets the scrolling window to 20
lines. If the screen is resized to 40 lines, the scrolling window automatically changes to 36
lines.
-"cc or --quotes=cc
Changes the filename quoting character. This may be necessary if you are trying to name a
file which contains both spaces and quote characters. Followed by a single character, this
changes the quote character to that character. Filenames containing a space should then be
surrounded by that character rather than by double quotes. Followed by two characters,
changes the open quote to the first character, and the close quote to the second character.
Filenames containing a space should then be preceded by the open quote character and followed
by the close quote character. Note that even after the quote characters are changed, this
option remains -" (a dash followed by a double quote).
-~ or --tilde
Normally lines after end of file are displayed as a single tilde (~). This option causes
lines after end of file to be displayed as blank lines.
-# or --shift
Specifies the default number of positions to scroll horizontally in the RIGHTARROW and LEFTAR-
ROW commands. If the number specified is zero, it sets the default number of positions to one
half of the screen width.
-- A command line argument of "--" marks the end of option arguments. Any arguments following
this are interpreted as filenames. This can be useful when viewing a file whose name begins
with a "-" or "+".
+ If a command line option begins with +, the remainder of that option is taken to be an initial
command to less. For example, +G tells less to start at the end of the file rather than the
beginning, and +/xyz tells it to start at the first occurrence of "xyz" in the file. As a
special case, +<number> acts like +<number>g; that is, it starts the display at the specified
line number (however, see the caveat under the "g" command above). If the option starts with
++, the initial command applies to every file being viewed, not just the first one. The +
command described previously may also be used to set (or change) an initial command for every
file.
LINE EDITING
When entering command line at the bottom of the screen (for example, a filename for the :e command,
or the pattern for a search command), certain keys can be used to manipulate the command line. Most
commands have an alternate form in [ brackets ] which can be used if a key does not exist on a par-
ticular keyboard. (The bracketed forms do not work in the MS-DOS version.) Any of these special
keys may be entered literally by preceding it with the "literal" character, either ^V or ^A. A back-
slash itself may also be entered literally by entering two backslashes.
LEFTARROW [ ESC-h ]
Move the cursor one space to the left.
RIGHTARROW [ ESC-l ]
Move the cursor one space to the right.
^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
(That is, CONTROL and LEFTARROW simultaneously.) Move the cursor one word to the left.
^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
(That is, CONTROL and RIGHTARROW simultaneously.) Move the cursor one word to the right.
HOME [ ESC-0 ]
Move the cursor to the beginning of the line.
END [ ESC-$ ]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or cancel the command if the command line is
empty.
DELETE or [ ESC-x ]
Delete the character under the cursor.
^BACKSPACE [ ESC-BACKSPACE ]
(That is, CONTROL and BACKSPACE simultaneously.) Delete the word to the left of the cursor.
^DELETE [ ESC-X or ESC-DELETE ]
(That is, CONTROL and DELETE simultaneously.) Delete the word under the cursor.
UPARROW [ ESC-k ]
Retrieve the previous command line.
DOWNARROW [ ESC-j ]
Retrieve the next command line.
TAB Complete the partial filename to the left of the cursor. If it matches more than one file-
name, the first match is entered into the command line. Repeated TABs will cycle thru the
other matching filenames. If the completed filename is a directory, a "/" is appended to the
filename. (On MS-DOS systems, a "\" is appended.) The environment variable LESSSEPARATOR can
be used to specify a different character to append to a directory name.
BACKTAB [ ESC-TAB ]
Like, TAB, but cycles in the reverse direction thru the matching filenames.
^L Complete the partial filename to the left of the cursor. If it matches more than one file-
name, all matches are entered into the command line (if they fit).
^U (Unix and OS/2) or ESC (MS-DOS)
Delete the entire command line, or cancel the command if the command line is empty. If you
have changed your line-kill character in Unix to something other than ^U, that character is
used instead of ^U.
KEY BINDINGS
You may define your own less commands by using the program lesskey (1) to create a lesskey file.
This file specifies a set of command keys and an action associated with each key. You may also use
lesskey to change the line-editing keys (see LINE EDITING), and to set environment variables. If the
environment variable LESSKEY is set, less uses that as the name of the lesskey file. Otherwise, less
looks in a standard place for the lesskey file: On Unix systems, less looks for a lesskey file called
"$HOME/.less". On MS-DOS and Windows systems, less looks for a lesskey file called "$HOME/_less",
and if it is not found there, then looks for a lesskey file called "_less" in any directory specified
in the PATH environment variable. On OS/2 systems, less looks for a lesskey file called
"$HOME/less.ini", and if it is not found, then looks for a lesskey file called "less.ini" in any
directory specified in the INIT environment variable, and if it not found there, then looks for a
lesskey file called "less.ini" in any directory specified in the PATH environment variable. See the
lesskey manual page for more details.
A system-wide lesskey file may also be set up to provide key bindings. If a key is defined in both a
local lesskey file and in the system-wide file, key bindings in the local file take precedence over
those in the system-wide file. If the environment variable LESSKEY_SYSTEM is set, less uses that as
the name of the system-wide lesskey file. Otherwise, less looks in a standard place for the system-
wide lesskey file: On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. (How-
ever, if less was built with a different sysconf directory than /usr/local/etc, that directory is
where the sysless file is found.) On MS-DOS and Windows systems, the system-wide lesskey file is
c:\_sysless. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.
INPUT PREPROCESSOR
You may define an "input preprocessor" for less. Before less opens a file, it first gives your input
preprocessor a chance to modify the way the contents of the file are displayed. An input preproces-
sor is simply an executable program (or shell script), which writes the contents of the file to a
different file, called the replacement file. The contents of the replacement file are then displayed
in place of the contents of the original file. However, it will appear to the user as if the origi-
nal file is opened; that is, less will display the original filename as the name of the current file.
An input preprocessor receives one command line argument, the original filename, as entered by the
user. It should create the replacement file, and when finished, print the name of the replacement
file to its standard output. If the input preprocessor does not output a replacement filename, less
uses the original file, as normal. The input preprocessor is not called when viewing standard input.
To set up an input preprocessor, set the LESSOPEN environment variable to a command line which will
invoke your input preprocessor. This command line should include one occurrence of the string "%s",
which will be replaced by the filename when the input preprocessor command is invoked.
When less closes a file opened in such a way, it will call another program, called the input postpro-
cessor, which may perform any desired clean-up action (such as deleting the replacement file created
by LESSOPEN). This program receives two command line arguments, the original filename as entered by
the user, and the name of the replacement file. To set up an input postprocessor, set the LESSCLOSE
environment variable to a command line which will invoke your input postprocessor. It may include
two occurrences of the string "%s"; the first is replaced with the original name of the file and the
second with the name of the replacement file, which was output by LESSOPEN.
For example, on many Unix systems, these two scripts will allow you to keep files in compressed for-
mat, but still let less view them directly:
lessopen.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac
lessclose.sh:
#! /bin/sh
rm $2
To use these scripts, put them both where they can be executed and set LESSOPEN="lessopen.sh %s", and
LESSCLOSE="lessclose.sh %s %s". More complex LESSOPEN and LESSCLOSE scripts may be written to accept
other types of compressed files, and so on.
It is also possible to set up an input preprocessor to pipe the file data directly to less, rather
than putting the data into a replacement file. This avoids the need to decompress the entire file
before starting to view it. An input preprocessor that works this way is called an input pipe. An
input pipe, instead of writing the name of a replacement file on its standard output, writes the
entire contents of the replacement file on its standard output. If the input pipe does not write any
characters on its standard output, then there is no replacement file and less uses the original file,
as normal. To use an input pipe, make the first character in the LESSOPEN environment variable a
vertical bar (|) to signify that the input preprocessor is an input pipe.
For example, on many Unix systems, this script will work like the previous example scripts:
lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
;;
esac
To use this script, put it where it can be executed and set LESSOPEN="|lesspipe.sh %s". When an
input pipe is used, a LESSCLOSE postprocessor can be used, but it is usually not necessary since
there is no replacement file to clean up. In this case, the replacement file name passed to the
LESSCLOSE postprocessor is "-".
NATIONAL CHARACTER SETS
There are three types of characters in the input file:
normal characters
can be displayed directly to the screen.
control characters
should not be displayed directly, but are expected to be found in ordinary text files (such as
backspace and tab).
binary characters
should not be displayed directly and are not expected to be found in text files.
A "character set" is simply a description of which characters are to be considered normal, control,
and binary. The LESSCHARSET environment variable may be used to select a character set. Possible
values for LESSCHARSET are:
ascii BS, TAB, NL, CR, and formfeed are control characters, all chars with values between 32 and 126
are normal, and all others are binary.
iso8859
Selects an ISO 8859 character set. This is the same as ASCII, except characters between 160
and 255 are treated as normal characters.
latin1 Same as iso8859.
latin9 Same as iso8859.
dos Selects a character set appropriate for MS-DOS.
ebcdic Selects an EBCDIC character set.
IBM-1047
Selects an EBCDIC character set used by OS/390 Unix Services. This is the EBCDIC analogue of
latin1. You get similar results by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in
your environment.
koi8-r Selects a Russian character set.
next Selects a character set appropriate for NeXT computers.
utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
windows
Selects a character set appropriate for Microsoft Windows (cp 1251).
In special cases, it may be desired to tailor less to use a character set other than the ones defin-
able by LESSCHARSET. In this case, the environment variable LESSCHARDEF can be used to define a
character set. It should be set to a string where each character in the string represents one char-
acter in the character set. The character "." is used for a normal character, "c" for control, and
"b" for binary. A decimal number may be used for repetition. For example, "bccc4b." would mean
character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal. All char-
acters after the last are taken to be the same as the last, so characters 9 through 255 would be nor-
mal. (This is an example, and does not necessarily represent any real character set.)
This table shows the value of LESSCHARDEF which is equivalent to each of the possible values for
LESSCHARSET:
ascii 8bcccbcc18b95.b
dos 8bcccbcc12bc5b95.b.
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
191.b
iso8859 8bcccbcc18b95.33b.
koi8-r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb
If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings "UTF-8", "UTF8", "utf-8" or
"utf8" is found in the LC_ALL, LC_TYPE or LANG environment variables, then the default character set
is utf-8.
If that string is not found, but your system supports the setlocale interface, less will use setlo-
cale to determine the character set. setlocale is controlled by setting the LANG or LC_CTYPE envi-
ronment variables.
Finally, if the setlocale interface is also not available, the default character set is latin1.
Control and binary characters are displayed in standout (reverse video). Each such character is dis-
played in caret notation if possible (e.g. ^A for control-A). Caret notation is used only if invert-
ing the 0100 bit results in a normal printable character. Otherwise, the character is displayed as a
hex number in angle brackets. This format can be changed by setting the LESSBINFMT environment vari-
able. LESSBINFMT may begin with a "*" and one character to select the display attribute: "*k" is
blinking, "*d" is bold, "*u" is underlined, "*s" is standout, and "*n" is normal. If LESSBINFMT does
not begin with a "*", normal attribute is assumed. The remainder of LESSBINFMT is a string which may
include one printf-style escape sequence (a % followed by x, X, o, d, etc.). For example, if LESS-
BINFMT is "*u[%x]", binary characters are displayed in underlined hexadecimal surrounded by brackets.
The default if no LESSBINFMT is specified is "*s<%X>". The default if no LESSBINFMT is specified is
"*s<%02X>". Warning: the result of expanding the character via LESSBINFMT must be less than 31 char-
acters.
When the character set is utf-8, the LESSUTFBINFMT environment variable acts similarly to LESSBINFMT
but it applies to Unicode code points that were successfully decoded but are unsuitable for display
(e.g., unassigned code points). Its default value is "<U+%04lX>". Note that LESSUTFBINFMT and LESS-
BINFMT share their display attribute setting ("*x") so specifying one will affect both; LESSUTFBINFMT
is read after LESSBINFMT so its setting, if any, will have priority. Problematic octets in a UTF-8
file (octets of a truncated sequence, octets of a complete but non-shortest form sequence, illegal
octets, and stray trailing octets) are displayed individually using LESSBINFMT so as to facilitate
diagnostic of how the UTF-8 file is ill-formed.
PROMPTS
The -P option allows you to tailor the prompt to your preference. The string given to the -P option
replaces the specified prompt string. Certain characters in the string are interpreted specially.
The prompt mechanism is rather complicated to provide flexibility, but the ordinary user need not
understand the details of constructing personalized prompt strings.
A percent sign followed by a single character is expanded according to what the following character
is:
%bX Replaced by the byte offset into the current input file. The b is followed by a single char-
acter (shown as X above) which specifies the line whose byte offset is to be used. If the
character is a "t", the byte offset of the top line in the display is used, an "m" means use
the middle line, a "b" means use the bottom line, a "B" means use the line just after the bot-
tom line, and a "j" means use the "target" line, as specified by the -j option.
%B Replaced by the size of the current input file.
%c Replaced by the column number of the text appearing in the first column of the screen.
%dX Replaced by the page number of a line in the input file. The line to be used is determined by
the X, as with the %b option.
%D Replaced by the number of pages in the input file, or equivalently, the page number of the
last line in the input file.
%E Replaced by the name of the editor (from the VISUAL environment variable, or the EDITOR envi-
ronment variable if VISUAL is not defined). See the discussion of the LESSEDIT feature below.
%f Replaced by the name of the current input file.
%i Replaced by the index of the current file in the list of input files.
%lX Replaced by the line number of a line in the input file. The line to be used is determined by
the X, as with the %b option.
%L Replaced by the line number of the last line in the input file.
%m Replaced by the total number of input files.
%pX Replaced by the percent into the current input file, based on byte offsets. The line used is
determined by the X as with the %b option.
%PX Replaced by the percent into the current input file, based on line numbers. The line used is
determined by the X as with the %b option.
%s Same as %B.
%t Causes any trailing spaces to be removed. Usually used at the end of the string, but may
appear anywhere.
%x Replaced by the name of the next input file in the list.
If any item is unknown (for example, the file size if input is a pipe), a question mark is printed
instead.
The format of the prompt string can be changed depending on certain conditions. A question mark fol-
lowed by a single character acts like an "IF": depending on the following character, a condition is
evaluated. If the condition is true, any characters following the question mark and condition char-
acter, up to a period, are included in the prompt. If the condition is false, such characters are
not included. A colon appearing between the question mark and the period can be used to establish an
"ELSE": any characters between the colon and the period are included in the string if and only if the
IF condition is false. Condition characters (which follow a question mark) may be:
?a True if any characters have been included in the prompt so far.
?bX True if the byte offset of the specified line is known.
?B True if the size of current input file is known.
?c True if the text is horizontally shifted (%c is not zero).
?dX True if the page number of the specified line is known.
?e True if at end-of-file.
?f True if there is an input filename (that is, if input is not a pipe).
?lX True if the line number of the specified line is known.
?L True if the line number of the last line in the file is known.
?m True if there is more than one input file.
?n True if this is the first prompt in a new input file.
?pX True if the percent into the current input file, based on byte offsets, of the specified line
is known.
?PX True if the percent into the current input file, based on line numbers, of the specified line
is known.
?s Same as "?B".
?x True if there is a next input file (that is, if the current input file is not the last one).
Any characters other than the special ones (question mark, colon, period, percent, and backslash)
become literally part of the prompt. Any of the special characters may be included in the prompt
literally by preceding it with a backslash.
Some examples:
?f%f:Standard input.
This prompt prints the filename, if known; otherwise the string "Standard input".
?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
This prompt would print the filename, if known. The filename is followed by the line number, if
known, otherwise the percent if known, otherwise the byte offset if known. Otherwise, a dash is
printed. Notice how each question mark has a matching period, and how the % after the %pt is
included literally by escaping it with a backslash.
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
This prints the filename if this is the first prompt in a file, followed by the "file N of N" message
if there is more than one input file. Then, if we are at end-of-file, the string "(END)" is printed
followed by the name of the next file, if there is one. Finally, any trailing spaces are truncated.
This is the default prompt. For reference, here are the defaults for the other two prompts (-m and
-M respectively). Each is broken into two lines here for readability only.
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
?pB%pB\%:byte %bB?s/%s...%t
?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
And here is the default message produced by the = command:
?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
The prompt expansion features are also used for another purpose: if an environment variable LESSEDIT
is defined, it is used as the command to be executed when the v command is invoked. The LESSEDIT
string is expanded in the same way as the prompt strings. The default value for LESSEDIT is:
%E ?lm+%lm. %f
Note that this expands to the editor name, followed by a + and the line number, followed by the file
name. If your editor does not accept the "+linenumber" syntax, or has other differences in invoca-
tion syntax, the LESSEDIT variable can be changed to modify this default.
SECURITY
When the environment variable LESSSECURE is set to 1, less runs in a "secure" mode. This means these
features are disabled:
! the shell command
| the pipe command
:e the examine command.
v the editing command
s -o log files
-k use of lesskey files
-t use of tags files
metacharacters in filenames, such as *
filename completion (TAB, ^L)
Less can also be compiled to be permanently in "secure" mode.
ENVIRONMENT VARIABLES
Environment variables may be specified either in the system environment as usual, or in a lesskey (1)
file. If environment variables are defined in more than one place, variables defined in a local
lesskey file take precedence over variables defined in the system environment, which take precedence
over variables defined in the system-wide lesskey file.
COLUMNS
Sets the number of columns on the screen. Takes precedence over the number of columns speci-
fied by the TERM variable. (But if you have a windowing system which supports TIOCGWINSZ or
WIOCGETD, the window system's idea of the screen size takes precedence over the LINES and COL-
UMNS environment variables.)
EDITOR The name of the editor (used for the v command).
HOME Name of the user's home directory (used to find a lesskey file on Unix and OS/2 systems).
HOMEDRIVE, HOMEPATH
Concatenation of the HOMEDRIVE and HOMEPATH environment variables is the name of the user's
home directory if the HOME variable is not set (only in the Windows version).
INIT Name of the user's init directory (used to find a lesskey file on OS/2 systems).
LANG Language for determining the character set.
LC_CTYPE
Language for determining the character set.
LESS Options which are passed to less automatically.
LESSANSIENDCHARS
Characters which may end an ANSI color escape sequence (default "m").
LESSANSIMIDCHARS
Characters which may appear between the ESC character and the end character in an ANSI color
escape sequence (default "0123456789;[?!"'#%()*+ ".
LESSBINFMT
Format for displaying non-printable, non-control characters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSCLOSE
Command line to invoke the (optional) input-postprocessor.
LESSECHO
Name of the lessecho program (default "lessecho"). The lessecho program is needed to expand
metacharacters, such as * and ?, in filenames on Unix systems.
LESSEDIT
Editor prototype string (used for the v command). See discussion under PROMPTS.
LESSGLOBALTAGS
Name of the command used by the -t option to find global tags. Normally should be set to
"global" if your system has the global (1) command. If not set, global tags are not used.
LESSHISTFILE
Name of the history file used to remember search commands and shell commands between invoca-
tions of less. If set to "-", a history file is not used. The default is "$HOME/.lesshst" on
Unix systems, "$HOME/_lesshst" on DOS and Windows systems, or "$HOME/lesshst.ini" or
"$INIT/lesshst.ini" on OS/2 systems.
LESSHISTSIZE
The maximum number of commands to save in the history file. The default is 100.
LESSKEY
Name of the default lesskey(1) file.
LESSKEY_SYSTEM
Name of the default system-wide lesskey(1) file.
LESSMETACHARS
List of characters which are considered "metacharacters" by the shell.
LESSMETAESCAPE
Prefix which less will add before each metacharacter in a command sent to the shell. If LESS-
METAESCAPE is an empty string, commands containing metacharacters will not be passed to the
shell.
LESSOPEN
Command line to invoke the (optional) input-preprocessor.
LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.
LESSSEPARATOR
String to be appended to a directory name in filename completion.
LESSUTFBINFMT
Format for displaying non-printable Unicode code points.
LINES Sets the number of lines on the screen. Takes precedence over the number of lines specified
by the TERM variable. (But if you have a windowing system which supports TIOCGWINSZ or
WIOCGETD, the window system's idea of the screen size takes precedence over the LINES and COL-
UMNS environment variables.)
PATH User's search path (used to find a lesskey file on MS-DOS and OS/2 systems).
SHELL The shell used to execute the ! command, as well as to expand filenames.
TERM The type of terminal on which less is being run.
VISUAL The name of the editor (used for the v command).
SEE ALSO
lesskey(1)
WARNINGS
The = command and prompts (unless changed by -P) report the line numbers of the lines at the top and
bottom of the screen, but the byte and percent of the line after the one at the bottom of the screen.
If the :e command is used to name more than one file, and one of the named files has been viewed pre-
viously, the new files may be entered into the list in an unexpected order.
On certain older terminals (the so-called "magic cookie" terminals), search highlighting will cause
an erroneous display. On such terminals, search highlighting is disabled by default to avoid possi-
ble problems.
In certain cases, when search highlighting is enabled and a search pattern begins with a ^, more text
than the matching string may be highlighted. (This problem does not occur when less is compiled to
use the POSIX regular expression package.)
When viewing text containing ANSI color escape sequences using the -R option, searching will not find
text containing an embedded escape sequence. Also, search highlighting may change the color of some
of the text which follows the highlighted text.
On some systems, setlocale claims that ASCII characters 0 thru 31 are control characters rather than
binary characters. This causes less to treat some binary files as ordinary, non-binary files. To
workaround this problem, set the environment variable LESSCHARSET to "ascii" (or whatever character
set is appropriate).
This manual is too long.
See http://www.greenwoodsoftware.com/less for the list of known bugs in all versions of less.
COPYRIGHT
Copyright (C) 1984-2005 Mark Nudelman
less is part of the GNU project and is free software. You can redistribute it and/or modify it under
the terms of either (1) the GNU General Public License as published by the Free Software Foundation;
or (2) the Less License. See the file README in the less distribution for more details regarding
redistribution. You should have received a copy of the GNU General Public License along with the
source for less; see the file COPYING. If not, write to the Free Software Foundation, 59 Temple
Place, Suite 330, Boston, MA 02111-1307, USA. You should also have received a copy of the Less
License; see the file LICENSE.
less is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
AUTHOR
Mark Nudelman <markn@greenwoodsoftware.com>
Send bug reports or comments to the above address or to bug-less@gnu.org.
For more information, see the less homepage at http://www.greenwoodsoftware.com/less
Version 394: 03 Dec 2005 LESS(1)
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