tset(1) General Commands Manual tset(1)
Name
tset - set terminal mode
Syntax
tset [options] [-m[ident] [test baudrate]:type] ... [ type ]
reset ...
Description
The command sets up your terminal when you first log in to a UNIX system. It does terminal dependent processing such as setting erase and
kill characters, setting or resetting delays, sending any sequences needed to properly initialized the terminal, and the like. It first
determines the type of terminal involved, and then does necessary initializations and mode settings. The type of terminal attached to each
UNIX port is specified in the /etc/ttys database. Type names for terminals may be found in the database. If a port is not wired perma-
nently to a specific terminal (not hardwired) it is given an appropriate generic identifier such as dialup.
In the case where no arguments are specified, simply reads the terminal type out of the environment variable TERM and re-initializes the
terminal. The rest of this manual concerns itself with mode and environment initialization, typically done once at login, and options used
at initialization time to determine the terminal type and set up terminal modes.
When used in a startup script (.profile for users or .login for users) it is desirable to give information about the type of terminal you
will usually use on ports which are not hardwired. These ports are identified in as dialup or plugboard or arpanet. To specify what ter-
minal type you usually use on these ports, the -m (map) option flag is followed by the appropriate port type identifier, an optional baud
rate specification, and the terminal type. (The effect is to ``map'' from some conditions to a terminal type, that is, to tell ``If I'm on
this kind of port, guess that I'm on that kind of terminal''.) If more than one mapping is specified, the first applicable mapping pre-
vails. A missing port type identifier matches all identifiers. Any of the alternate generic names given in may be used for the identi-
fier.
A baudrate is specified as with and is compared with the speed of the diagnostic output (which should be the control terminal). The baud
rate test may be any combination of: >, @, <, and !; @ means ``at'' and ! inverts the sense of the test. To avoid problems with metachar-
acters, it is best to place the entire argument to -m within ``''' characters; users of must also put a ``'' before any ``!'' used here.
Thus
tset -m 'dialup>300:adm3a' -m dialup:dw2 -m 'plugboard:?adm3a'
causes the terminal type to be set to an adm3a if the port in use is a dialup at a speed greater than 300 baud; to a dw2 if the port is
(otherwise) a dialup (that is, at 300 baud or less). (The examples given here appear to take up more than one line, for text processing
reasons. When you type in real commands, you must enter them entirely on one line.) If the type finally determined by begins with a ques-
tion mark, the user is asked if he really wants that type. A null response means to use that type; otherwise, another type can be entered
which is used instead. Thus, in the above case, the user is queried on a plugboard port as to whether they are actually using an adm3a.
If no mapping applies and a final type option, not preceded by a -m, is given on the command line then that type is used; otherwise the
identifier found in the database is assumed to be the terminal type. This should always be the case for hardwired ports.
It is usually desirable to return the terminal type, as finally determined by and information about the terminal's capabilities to a
shell's environment. This can be done using the - option; using the Bourne shell,
export TERM; TERM=`tset - options...`
Or using the C shell,
setenv TERM `tset - options...`
With it is convenient to make an alias in your .cshrc:
alias tset 'setenv TERM `tset - !*`'
Either of these aliases allow the command
tset 2621
to be invoked at any time from your login If you are using the Bourne shell, it is not possible to get this aliasing effect with a shell
script, because shell scripts cannot set the environment of their parent.
These commands cause to place the name of your terminal in the variable TERM in the environment. For further information, see
Once the terminal type is known, engages in terminal driver mode setting. This normally involves sending an initialization sequence to the
terminal, setting the single character erase (and optionally the line-kill (full line erase)) characters, and setting special character
delays. Tab and newline expansion are turned off during transmission of the terminal initialization sequence.
On terminals that can backspace but not overstrike (such as a CRT), and when the erase character is the default erase character (`#' on
standard systems), the erase character is changed to BACKSPACE (Control-H).
If is invoked as it will set cooked and echo modes, turn off cbreak and raw modes, turn on newline translation, and restore special charac-
ters to a sensible state before any terminal dependent processing is done. Any special character that is found to be NULL or ``-1'' is
reset to its default value.
This is most useful after a program dies leaving a terminal in a funny state. You may have to type ``<LF>reset<LF>'' to get it to work
since <CR> may not work in this state. Often none of this will echo.
Options
- Name of terminal is output on stndout, captured by the shell, and placed in the environment variable TERM.
-ec Uses the specified character as the erase character. The default is the backspace character on the terminal, usually ^H. The charac-
ter c can either be typed directly, or entered using the hat notation used here.
-I Suppresses transmitting terminal initialization strings.
-kc Uses the specified character as the kill character. It is similar to -e but for the line kill character rather than the erase charac-
ter; c defaults to ^X (for purely historical reasons). The kill characters is left alone if -k is not specified. The hat notation
can also be used for this option.
-n Initializes the new tty driver, if applicable. On systems with the Berkeley 4BSD tty driver, specifies that the new tty driver modes
should be initialized for this terminal. For a CRT, the CRTERASE and CRTKILL modes are set only if the baud rate is 1200 or greater.
See for more detail.
-Q Suppresses erase and kill character message.
-s Output commands for TERM. This option can be used with tset -s ... and is to be preferred to setenv TERM tset - ... because -s also
sets the TERMCAP variable.
-S Similar to -s, but outputs 2 strings suitable for use in csh files as follows:
set noglob
set term=(`tset -S .....`)
setenv TERM $term[1]
setenv TERMCAP "$term[2]"
unset term
unset noglob
Restrictions
For compatibility with earlier versions of a number of flags are accepted whose use is discouraged:
-d type equivalent to -m dialup:type
-p type equivalent to -m plugboard:type
-a type equivalent to -m arpanet:type
-E c Sets the erase character to c only if the terminal can backspace.
- prints the terminal type on the standard output
-r prints the terminal type on the diagnostic output.
Examples
These examples all assume the Bourne shell and use the - option. If you use use one of the variations described above. Note that a typi-
cal use of in a .profile or .login will also use the -e and -k options, and often the -n or -Q options as well. These options have not
been included here to keep the examples small. (NOTE: some of the examples given here appear to take up more than one line, for text pro-
cessing reasons. When you type in real commands, you must enter them entirely on one line.)
At the moment, you are on a 2621. This is suitable for typing by hand but not for a .profile, unless you are always on a 2621.
export TERM; TERM=`tset - 2621`
You have an h19 at home which you dial up on, but your office terminal is hardwired and known in /etc/ttys.
export TERM; TERM=`tset - -m dialup:h19`
You have a switch which connects everything to everything, making it nearly impossible to key on what port you are coming in on. You use a
vt100 in your office at 9600 baud, and dial up to switch ports at 1200 baud from home on a 2621. Sometimes you use someone elses terminal
at work, so you want it to ask you to make sure what terminal type you have at high speeds, but at 1200 baud you are always on a 2621.
Note the placement of the question mark, and the quotes to protect the greater than and question mark from interpretation by the shell.
export TERM; TERM=`tset - -m 'switch>1200:?vt100' -m
'switch<=1200:2621'
All of the above entries will fall back on the terminal type specified in if none of the conditions hold. The following entry is appropri-
ate if you always dial up, always at the same baud rate, on many different kinds of terminals. Your most common terminal is an adm3a. It
always asks you what kind of terminal you are on, defaulting to adm3a.
export TERM; TERM=`tset - .EE
If the file
is not properly installed and you want to
key entirely on the baud rate, the following can be used:
export TERM; TERM=`tset - -m '>1200:vt100' 2621`
Here is a fancy example to illustrate the power of and to hopelessly confuse anyone who has made it this far. You dial up at 1200 baud or
less on a concept100, sometimes over switch ports and sometimes over regular dialups. You use various terminals at speeds higher than 1200
over switch ports, most often the terminal in your office, which is a vt100. However, sometimes you log in from the university you used to
go to, over the ARPANET; in this case you are on an ALTO emulating a dm2500. You also often log in on various hardwired ports, such as the
console, all of which are properly entered in You want your erase character set to control H, your kill character set to control U, and do
not want to print the ``Erase set to Backspace, Kill set to Control U'' message.
export TERM; TERM=`tset -e -k^U -Q - -m
'switch<=1200:concept100' -m 'switch:?vt100' -m
dialup:concept100 -m arpanet:dm2500`
Files
port name to terminal type mapping database
terminal capability database
See Also
csh(1), sh(1), stty(1), termcap(5), ttys(5), environ(7)
tset(1)