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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
System-V-like UNIXes and systems using that convention, 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 TER-
MINAL 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 dis-
played to the standard error output. Use the -c or -w option to select only the window sizing versus the other initial-
ization. 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 newline 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 displays 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 envi-
ronment. 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 commands are for csh, otherwise, they are for
sh. Note, the csh commands set and unset the shell variable 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 something 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 specifica-
tion, an optional colon (``:'') character and a terminal type. The port type is a string (delimited by either the opera-
tor or the colon character). The operator may be any combination 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 compared with the speed of the standard error output (which should be the control terminal). The termi-
nal type is a string.
If the terminal type is not specified on the command line, the -m mappings are applied to the terminal type. If the port
type and baud rate match the mapping, the terminal type specified in the mapping 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 operator is >, the baud
rate specification is 9600, and the terminal type is vt100. The result of this mapping is to specify that if the termi-
nal 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 specified, 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 ter-
minal.
No whitespace characters are permitted in the -m option argument. Also, to avoid problems with meta-characters, it is
suggested that the entire -m option argument be placed within single quote characters, and that csh users insert a back-
slash 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 ter-
minfo environment by Eric S. Raymond <esrATsnark.com>.
COMPATIBILITY
The tset utility has been provided for backward-compatibility with BSD environments (under most modern UNIXes, /etc/init-
tab 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 exceptions 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 similarly 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 these environment variables:
SHELL
tells tset whether to initialize TERM using sh or csh syntax.
TERM Denotes your terminal type. Each terminal type is distinct, though many are similar.
TERMCAP
may denote the location of a termcap database. If it is not an absolute pathname, e.g., begins with a `/', tset
removes the variable from the environment before looking for the terminal description.
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), curs_terminfo(3X), tty(4), terminfo(5), ttys(5), environ(7)
This describes ncurses version 5.7 (patch 20100703).
tset(1)
