NAME

tset − set terminal modes

SYNOPSIS

tset [ options ] [ −m [ident][test baudrate]:type ...  ] [ type ]

DESCRIPTION

Tset causes terminal dependent processing, such as, setting erase and kill characters, setting or resetting delays, and other similar functions.  It first determines the type of terminal involved, names for which are specified by the /etc/termcap data base, and then does necessary initializations and mode settings.  In the case where no argument types are specified, tset simply reads the terminal type out of the environment variable TERM and re-initializes the terminal.  The rest of this manual concerns itself with type initialization, done typically 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 sh(1) users) or .login (for csh(1) users) it is desirable to give information about the types of terminal usually used on terminals which are not hardwired. These ports are initially identified as being dialup or plugboard or arpanet etc.  To specify what terminal type is usually used on these ports −m is followed by the appropriate port type identifier, an optional baud-rate specification, and the terminal type to be used if the mapping conditions are satisfied.  If more than one mapping is specified, the first applicable mapping prevails.  A missing type identifier matches all identifiers. 

Baud rates are specified as with stty(1), and are compared with the speed of the diagnostic output (which is almost always the control terminal). The baud rate test may be any combination of: >, =, <, @, and !; @ is a synonym for = and !  inverts the sense of the test.  To avoid problems with metacharacters, it is best to place the entire argument to −m within “´” characters; users of csh(1) 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 (i.e. at 300 baud or less).  If the type above begins with a question mark, the user is asked if s/he really wants that type.  A null response means to use that type; otherwise, another type can be entered which will be used instead.  Thus, in this case, the user will be queried on a plugboard port as to whether they are using an adm3a.  For other ports the port type will be taken from the /etc/ttytype file or a final, default type option may be given on the command line not preceded by a −m. 

It is often desirable to return the terminal type, as specified by the −m options, and information about the terminal to a shell’s environment.  This can be done using the −s option; using the Bourne shell, sh(1):

eval `tset −s options...`

or using the C shell, csh(1):

set noglob; eval `tset −s options...`

These commands cause tset to generate as output a sequence of shell commands which place the variables TERM and TERMCAP in the environment; see environ(5).

Once the terminal type is known, tset engages in terminal mode setting.  This normally involves sending an initialization sequence to the terminal and setting the single character erase (and optionally the line-kill (full line erase)) characters. 

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 a Control-H (backspace). 

The options are:

−e set the erase character to be the named character c on all terminals, the default being the backspace character on the terminal, usually ^H. 

−k is similar to −e but for the line kill character rather than the erase character; c defaults to ^X (for purely historical reasons); ^U is the preferred setting.  No kill processing is done if −k is not specified. 

−I supresses outputting terminal initialization strings. 

−Q supresses printing the “Erase set to” and “Kill set to” messages. 

−S Outputs the strings to be assigned to TERM and TERMCAP in the environment rather than commands for a shell. 

−s Outputs setenv commands. 

−h Do not read from htmp or env. 

−u Do not update htmp. 

FILES

/etc/ttytypeterminal id to type map database
/etc/termcapterminal capability database

SEE ALSO

csh(1), setenv(1), sh(1), stty(1), environ(5), ttytype(5), termcap(5)

AUTHOR

Eric Allman

BUGS

Should be merged with stty(1).

NOTES

For compatibility with earlier versions of tset 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. 

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