tset, reset - terminal initialization
tset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping]
reset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping]
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
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 ter-
minal 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 ter-
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 initializa-
tion 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 transla-
tion 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
(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 infor-
-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 out-
put, 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' nota-
tion, 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 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
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 specifi-
cation, 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
terminal). 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 applica-
ble 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 termi-
nal type is vt100. The result of this mapping is to spec-
ify that if the terminal type is dialup, and the baud rate
is greater than 9600 baud, a terminal type of vt100 will
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 exclama-
tion marks (``!'').
The tset command appeared in BSD 3.0. The ncurses imple-
mentation was lightly adapted from the 4.4BSD sources for
a terminfo environment by Eric S. Raymond <firstname.lastname@example.org-
The tset utility has been provided for backward-compati-
bility 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 begin-
ning 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 recom-
mended that such usage be fixed to explicitly specify the
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.
The tset command uses these environment variables:
tells tset whether to initialize TERM using sh or csh
TERM Denotes your terminal type. Each terminal type is
distinct, though many are similar.
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.
system port name to terminal type mapping database
(BSD versions only).
terminal capability database
csh(1), sh(1), stty(1), curs_terminfo(3x), tty(4), ter-
minfo(5), ttys(5), environ(7)
This describes ncurses version 5.6 (patch 20080621).
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