Manual Pages for UNIX Operating System command usage for man tset
User Commands 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 set-
ting 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, back-
space, 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 newline translation
and resets any unset special characters to their default
values before doing the terminal initialization described
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User Commands tset(1)
above. This is useful after a program dies leaving a termi-
nal in an abnormal state. Note, you may have to type
reset
(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 setup-
term. 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''.
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User Commands tset(1)
SETTING THE ENVIRONMENT
It is often desirable to enter the terminal type and infor-
mation 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 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 con-
ditions 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
operator 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 termi-
nal). The terminal 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
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User Commands tset(1)
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 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
terminal.
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
backslash character (``\'') before any exclamation marks
(``!'').
HISTORY
The tset command appeared in BSD 3.0. The ncurses implemen-
tation was lightly adapted from the 4.4BSD sources for a
terminfo environment by Eric S. Raymond
.
COMPATIBILITY
The tset utility has been provided for backward-
compatibility with BSD environments (under most modern
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 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
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User Commands tset(1)
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 recom-
mended 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 dis-
tinct, 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/gnu/share/terminfo
terminal capability database
SEE ALSO
csh(1), sh(1), stty(1), curs_terminfo(3X), tty(4), ter-
minfo(5), ttys(5), environ(7)
This describes ncurses version 5.7 (patch 20081102).
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