tset initializes terminals.
tset first determines the type of terminal that you
are using. This determination is done as follows, using the first terminal
- The terminal argument specified on the command line.
- The value of the
- The terminal type associated with the standard error output device in the /etc/ttys file.
- 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
TERMINAL TYPE MAPPING
section below 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
-w option to select only the window sizing versus
the other initialization. If neither option is given, both are assumed.
When invoked as
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 options are as follows:
- The terminal type is displayed to the standard output, and the terminal is
not initialized in any way. This option has been deprecated in favor of
- Set control characters and modes.
- Set the erase character to ch.
- Do not send the terminal or tab initialization strings to the terminal.
- Set the interrupt character to ch.
- Set the line kill character to ch.
- Specify a mapping from a port type to a terminal. See the TERMINAL TYPE MAPPING section below for more information.
- Don't display any values for the erase, interrupt and line kill
tsetdisplays the values for control characters which differ from the system's default values.
- The terminal type is displayed to the standard output, and the terminal is not initialized in any way.
- Print the terminal type to the standard error output.
- Print the sequence of shell commands to initialize the environment
TERMto the standard output. See the SETTING THE ENVIRONMENT section below for details.
- Report the version of ncurses which was used in this program, and exit.
- Resize the window to match the size deduced via setupterm(3). Normally this has no effect, unless setupterm(3) is not able to detect the window size.
The arguments for the
-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
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
-s option is specified, the
commands to enter the information into the shell's environment are written
to the standard output. If the
variable ends in “csh”, the commands are for
csh(1), otherwise, they are for
Note, the csh(1) 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
environment variable is often something generic like
“network”, “dialup”, or “unknown”.
tset is used in a startup script
users or .login for
csh(1) users), 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,
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
combination of: ‘
>’ 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 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 terminal type is “dialup”, and the baud rate is greater than 9600 baud, a terminal type of “vt100” will be used.
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
option argument be placed within single quote characters, and that
csh(1) users insert a backslash character
\’) before any exclamation marks
tset command utilizes the
- port name to terminal type mapping database
- terminal capability database
csh(1), sh(1), stty(1), tty(4), terminfo(5), ttys(5), environ(7)
tset command now uses the
terminfo(5) database where previous versions used
Historic versions of the
termcap(3) library limited entries to 1023 bytes. Modern
terminfo(3) entries are often much larger, making it impossible to
store the full entry in the
variable. Because of this, the
-S option is no
longer supported (it prints an error message to the standard error and
exits) and the
-s option only sets
-v options have been deleted from the
tset utility. None of them were documented in
4.3BSD and all are of limited utility at best. The
-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
option remains, but has no effect. It is still permissible to specify the
-k options without arguments, although it is
strongly recommended that such usage be fixed to explicitly specify the
reset no longer implies the
-Q option. Also, the interaction between the
- option and the terminal
argument in some historic implementations of
has been removed.
tset implementation has been
completely redone (as part of the addition to the system of a
IEEE Std 1003.1-1988 (“POSIX.1”)
compliant terminal interface) and will no longer compile on systems with
older terminal interfaces.
utilities first appeared in 1BSD.
The original version of
tset was written
by Eric P. Allman in October 1977, and
reset was originally written by
Kurt Shoens. The current version also contains code
by Zeyd M. Ben-Halim, Eric S.
Raymond, and Thomas E. Dickey.