tset(1) tset(1)
NAME
tset, reset - terminal initialization
SYNOPSIS
tset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
reset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
DESCRIPTION
Tset initializes terminals. Tset first determines the type of terminal that you are using. This
determination is done as follows, using the first terminal type found.
1. The terminal argument specified on the command line.
2. The value of the TERM environmental variable.
3. (BSD systems only.) The terminal type associated with the standard error output device in the
/etc/ttys file. (On Linux and System-V-like UNIXes, getty does this job by setting TERM according to
the type passed to it by /etc/inittab.)
4. The default terminal type, ``unknown''.
If the terminal type was not specified on the command-line, the -m option mappings are then applied
(see the section TERMINAL TYPE MAPPING for more information). Then, if the terminal type begins with
a question mark (``?''), the user is prompted for confirmation of the terminal type. An empty
response confirms the type, or, another type can be entered to specify a new type. Once the terminal
type has been determined, the terminfo entry for the terminal is retrieved. If no terminfo entry is
found for the type, the user is prompted for another terminal type.
Once the terminfo entry is retrieved, the window size, backspace, interrupt and line kill characters
(among many other things) are set and the terminal and tab initialization strings are sent to the
standard error output. Finally, if the erase, interrupt and line kill characters have changed, or
are not set to their default values, their values are displayed to the standard error output. Use
the -c or -w option to select only the window sizing versus the other initialization. If neither
option is given, both are assumed.
When invoked as reset, tset sets cooked and echo modes, turns off cbreak and raw modes, turns on new-line newline
line translation and resets any unset special characters to their default values before doing the
terminal initialization described above. This is useful after a program dies leaving a terminal in
an abnormal state. Note, you may have to type
<LF>reset<LF>
(the line-feed character is normally control-J) to get the terminal to work, as carriage-return may
no longer work in the abnormal state. Also, the terminal will often not echo the command.
The options are as follows:
-c Set control characters and modes. -e Set the erase character to ch.
-I Do not send the terminal or tab initialization strings to the terminal.
-i Set the interrupt character to ch.
-k Set the line kill character to ch.
-m Specify a mapping from a port type to a terminal. See the section TERMINAL TYPE MAPPING for
more information.
-Q Do not display any values for the erase, interrupt and line kill characters. Normally tset dis-plays displays
plays the values for control characters which differ from the system's default values.
-q The terminal type is displayed to the standard output, and the terminal is not initialized in
any way. The option `-' by itself is equivalent but archaic.
-r Print the terminal type to the standard error output.
-s Print the sequence of shell commands to initialize the environment variable TERM to the standard
output. See the section SETTING THE ENVIRONMENT for details.
-V reports the version of ncurses which was used in this program, and exits.
-w Resize the window to match the size deduced via setupterm. Normally this has no effect, unless
setupterm is not able to detect the window size.
The arguments for the -e, -i, and -k options may either be entered as actual characters or by using
the `hat' notation, i.e. control-h may be specified as ``^H'' or ``^h''.
SETTING THE ENVIRONMENT
It is often desirable to enter the terminal type and information about the terminal's capabilities
into the shell's environment. This is done using the -s option.
When the -s option is specified, the commands to enter the information into the shell's environment
are written to the standard output. If the SHELL environmental variable ends in ``csh'', the com-mands commands
mands are for csh, otherwise, they are for sh. Note, the csh commands set and unset the shell vari-able variable
able noglob, leaving it unset. The following line in the .login or .profile files will initialize
the environment correctly:
eval `tset -s options ... `
TERMINAL TYPE MAPPING
When the terminal is not hardwired into the system (or the current system information is incorrect)
the terminal type derived from the /etc/ttys file or the TERM environmental variable is often some-thing something
thing generic like network, dialup, or unknown. When tset is used in a startup script it is often
desirable to provide information about the type of terminal used on such ports.
The purpose of the -m option is to map from some set of conditions to a terminal type, that is, to
tell tset ``If I'm on this port at a particular speed, guess that I'm on that kind of terminal''.
The argument to the -m option consists of an optional port type, an optional operator, an optional
baud rate specification, an optional colon (``:'') character and a terminal type. The port type is a
string (delimited by either the operator or the colon character). The operator may be any combina-tion combination
tion of ``>'', ``<'', ``@'', and ``!''; ``>'' means greater than, ``<'' means less than, ``@'' means
equal to and ``!'' inverts the sense of the test. The baud rate is specified as a number and is com-
pared with the speed of the standard error output (which should be the control terminal). The termi-nal terminal
nal type is a string.
If the terminal type is not specified on the command line, the -m mappings are applied to the termi-nal terminal
nal type. If the port type and baud rate match the mapping, the terminal type specified in the map-ping mapping
ping replaces the current type. If more than one mapping is specified, the first applicable mapping
is used.
For example, consider the following mapping: dialup>9600:vt100. The port type is dialup , the opera-tor operator
tor is >, the baud rate specification is 9600, and the terminal type is vt100. The result of this
mapping is to specify that if the terminal type is dialup, and the baud rate is greater than 9600
baud, a terminal type of vt100 will be used.
If no baud rate is specified, the terminal type will match any baud rate. If no port type is speci-fied, specified,
fied, the terminal type will match any port type. For example, -m dialup:vt100 -m :?xterm will cause
any dialup port, regardless of baud rate, to match the terminal type vt100, and any non-dialup port
type to match the terminal type ?xterm. Note, because of the leading question mark, the user will be
queried on a default port as to whether they are actually using an xterm terminal.
No whitespace characters are permitted in the -m option argument. Also, to avoid problems with meta-characters, metacharacters,
characters, it is suggested that the entire -m option argument be placed within single quote charac-ters, characters,
ters, and that csh users insert a backslash character (``\'') before any exclamation marks (``!'').
HISTORY
The tset command appeared in BSD 3.0. The ncurses implementation was lightly adapted from the 4.4BSD
sources for a terminfo environment by Eric S. Raymond <esr@snark.thyrsus.com>.
COMPATIBILITY
The tset utility has been provided for backward-compatibility with BSD environments (under most mod-ern modern
ern UNIXes, /etc/inittab and getty(1) can set TERM appropriately for each dial-up line; this obviates
what was tset's most important use). This implementation behaves like 4.4BSD tset, with a few excep-tions exceptions
tions specified here.
The -S option of BSD tset no longer works; it prints an error message to stderr and dies. The -s
option only sets TERM, not TERMCAP. Both these changes are because the TERMCAP variable is no longer
supported under terminfo-based ncurses, which makes tset -S useless (we made it die noisily rather
than silently induce lossage).
There was an undocumented 4.4BSD feature that invoking tset via a link named `TSET` (or via any other
name beginning with an upper-case letter) set the terminal to use upper-case only. This feature has
been omitted.
The -A, -E, -h, -u and -v options were deleted from the tset utility in 4.4BSD. None of them were
documented in 4.3BSD and all are of limited utility at best. The -a, -d, and -p options are simi-larly similarly
larly not documented or useful, but were retained as they appear to be in widespread use. It is
strongly recommended that any usage of these three options be changed to use the -m option instead.
The -n option remains, but has no effect. The -adnp options are therefore omitted from the usage
summary above.
It is still permissible to specify the -e, -i, and -k options without arguments, although it is
strongly recommended that such usage be fixed to explicitly specify the character.
As of 4.4BSD, executing tset as reset no longer implies the -Q option. Also, the interaction between
the - option and the terminal argument in some historic implementations of tset has been removed.
ENVIRONMENT
The tset command uses the SHELL and TERM environment variables.
FILES
/etc/ttys
system port name to terminal type mapping database (BSD versions only).
/usr/share/terminfo
terminal capability database
SEE ALSO
csh(1), sh(1), stty(1), setupterm(3), tty(4), termcap(5), ttys(5), environ(7)
tset(1)
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