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TSET(1) General Commands Manual TSET(1)
NAME
tset, reset - terminal initialization
SYNOPSIS
tset [-IQrs] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
reset [-IQrs] [-] [-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.
⊕ The terminal argument specified on the command line.
⊕ The value of the TERM environmental variable.
⊕ 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 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.
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 a 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:
- The terminal type is displayed to the standard output, and the
terminal is not initialized in any way.
-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 below for
more information.
-Q Don't display any values for the erase, interrupt and line kill
characters.
-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 below on
setting the environment for details.
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 commands are for the
csh(1), otherwise, they are for sh(1). 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 ... `
To demonstrate a simple use of the -S option, the following lines in the
.login file have an equivalent effect:
set noglob
set term=(`tset -S options ...`)
setenv TERM $term[1]
unset term
unset noglob
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
(.profile for sh(1) 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, 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 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 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 metacharacters, it is suggested that the entire -m
option argument be placed within single quote characters, and that csh(1)
users insert a backslash character (``\'') before any exclamation marks
(``!'').
ENVIRONMENT
The tset command uses the SHELL and TERM environment variables.
FILES
/etc/ttys system port name to terminal type mapping
database
/usr/share/misc/terminfo terminal capability database
COMPATIBILITY
The -A, -E, -h, -u and -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 -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.
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.
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 -E and -S options have been removed as they only make sense for
termcap and tset now uses terminfo. As such, the TERMCAP entry has been
removed from -s.
Finally, the 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.
SEE ALSO
csh(1), sh(1), stty(1), tty(4), terminfo(5), ttys(5), environ(7)
HISTORY
The reset and tset commands appeared in 1BSD.
NetBSD 10.99 April 5, 2012 NetBSD 10.99