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tset

Section: User Commands (1)
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NAME

tset, reset - terminal initialization

SYNOPSIS

tset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
reset [-IQVcqrsw] [-] [-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.

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 standarderror output device in the /etc/ttys file. (On Linux andSystem-V-like UNIXes, getty does this job by settingTERM according to the type passed to it by /etc/inittab.)

4. The default terminal type, ``unknown''.

If the terminal type was not specified on the command-line, the -moption mappings are then applied (see the sectionTERMINAL TYPE MAPPINGfor more information).Then, if the terminal type begins with a question mark (``?''), theuser is prompted for confirmation of the terminal type. An emptyresponse confirms the type, or, another type can be entered to specifya new type. Once the terminal type has been determined, the terminfoentry for the terminal is retrieved. If no terminfo entry is foundfor the type, the user is prompted for another terminal type.

Once the terminfo entry is retrieved, the window size, backspace, interruptand line kill characters (among many other things) are set and the terminaland 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 thestandard error output.Use the -c or -w option to select only the window sizingversus 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 translation andresets any unset special characters to their default values beforedoing the terminal initialization described above. This is usefulafter 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 terminalto 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.-eSet 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 sectionTERMINAL TYPE MAPPINGfor more information.
-Q: Do not display any values for the erase, interrupt and line kill characters.Normally tset displays the values for control characters whichdiffer from the system's default values.
-q: The terminal type is displayed to the standard output, and the terminal isnot initialized in any way. The option `-' by itself is equivalent butarchaic.
-r: Print the terminal type to the standard error output.
-s: Print the sequence of shell commands to initialize the environment variableTERM to the standard output.See the sectionSETTING THE ENVIRONMENTfor 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 -koptions 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 aboutthe 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 informationinto the shell's environment are written to the standard output. Ifthe SHELL environmental variable ends in ``csh'', the commandsare for csh, otherwise, they are for sh.Note, the csh commands set and unset the shell variablenoglob, leaving it unset. The following line in the .loginor .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 currentsystem information is incorrect) the terminal type derived from the/etc/ttys file or the TERM environmental variable is oftensomething generic like network, dialup, or unknown.When tset is used in a startup script it is often desirable toprovide information about the type of terminal used on such ports.

The purpose of the -m option is to mapfrom some set of conditions to a terminal type, that is, totell tset``If I'm on this port at a particular speed, guess that I'm on thatkind of terminal''.

The argument to the -m option consists of an optional port type, anoptional operator, an optional baud rate specification, an optionalcolon (``:'') character and a terminal type. The port type is astring (delimited by either the operator or the colon character). Theoperator may be any combination of ``>'', ``<'', ``@'', and ``!''; ``>''means greater than, ``<'' means less than, ``@'' means equal toand ``!'' inverts the sense of the test.The baud rate is specified as a number and is compared with the speedof 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 -mmappings are applied to the terminal type. If the port type and baudrate match the mapping, the terminal type specified in the mappingreplaces the current type. If more than one mapping is specified, thefirst applicable mapping is used.

For example, consider the following mapping: dialup>9600:vt100.The port type is dialup , the operator is >, the baud ratespecification is 9600, and the terminal type is vt100. The result ofthis mapping is to specify that if the terminal type is dialup,and the baud rate is greater than 9600 baud, a terminal type ofvt100 will be used.

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 :?xtermwill cause any dialup port, regardless of baud rate, to match the terminaltype vt100, and any non-dialup port type to match the terminal type ?xterm.Note, because of the leading question mark, the user will bequeried on a default port as to whether they are actually using an xtermterminal.

No whitespace characters are permitted in the -m option argument.Also, to avoid problems with meta-characters, it is suggested that theentire -m option argument be placed within single quote characters,and that csh users insert a backslash character (``\'') beforeany exclamation marks (``!'').

HISTORY

The tset command appeared in BSD 3.0. The ncurses implementationwas lightly adapted from the 4.4BSD sources for a terminfo environment by EricS. Raymond <esrAATTsnark.thyrsus.com>.

COMPATIBILITY

The tset utility has been provided for backward-compatibility with BSDenvironments (under most modern UNIXes, /etc/inittab and getty(1)can set TERM appropriately for each dial-up line; this obviates what wastset's most important use). This implementation behaves like 4.4BSDtset, with a few exceptions specified here.

The -S option of BSD tset no longer works; it prints an error message to stderrand dies. The -s option only sets TERM, not TERMCAP. Both thesechanges are because the TERMCAP variable is no longer supported underterminfo-based ncurses, which makes tset -S useless (we made it dienoisily 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 beginning with an upper-case letter) set theterminal to use upper-case only. This feature has been omitted.

The -A, -E, -h, -u and -voptions were deleted from the tsetutility in 4.4BSD.None of them were documented in 4.3BSD and all areof limited utility at best.The -a, -d, and -p options are similarlynot documented or useful, but were retained as they appear to be inwidespread use. It is strongly recommended that any usage of thesethree options be changed to use the -m option instead. The-n option remains, but has no effect. The -adnp options are thereforeomitted from the usage summary above.

It is still permissible to specify the -e, -i, and -k options withoutarguments, although it is strongly recommended that such usage be fixed toexplicitly specify the character.

As of 4.4BSD, executing tset as reset no longer implies the -Qoption. Also, the interaction between the - option and the terminalargument in some historic implementations of tset has been removed.

ENVIRONMENT

The tset command uses these environment variables:

SHELL: tells tset whether to initialize TERM using sh orcsh syntax.
TERM: Denotes your terminal type.Each terminal type is distinct, though many are similar.
TERMCAP: 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 lookingfor the terminal description.

FILES

/etc/ttys: system port name to terminal type mapping database (BSD versions only).
/usr/share/terminfo: terminal capability database

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