tset(1) — Linux manual page


@TSET@(1)                  General Commands Manual                 @TSET@(1)

NAME         top

       @TSET@, @RESET@ - terminal initialization

SYNOPSIS         top

       @TSET@ [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping]
       @RESET@ [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping]

DESCRIPTION         top

   tset - initialization
       This program initializes terminals.

       First, @TSET@ retrieves the current terminal mode settings for your
       terminal.  It does this by successively testing

       ·   the standard error,

       ·   standard output,

       ·   standard input and

       ·   ultimately “/dev/tty”

       to obtain terminal settings.  Having retrieved these settings, @TSET@
       remembers which file descriptor to use when updating settings.

       Next, @TSET@ determines the type of terminal that you are using.
       This determination is done as follows, using the first terminal type

       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 standard
       error output device in the /etc/ttys file.  (On System-V-like UNIXes
       and systems using that convention, getty does this job by setting
       TERM 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 -m
       option mappings are then applied (see the section TERMINAL TYPE
       MAPPING 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 terminal description for the terminal is
       retrieved.  If no terminal description is found for the type, the
       user is prompted for another terminal type.

       Once the terminal description is retrieved,

       ·   if the “-w” option is enabled, @TSET@ may update the terminal's
           window size.

           If the window size cannot be obtained from the operating system,
           but the terminal description (or environment, e.g., LINES and
           COLUMNS variables specify this), use this to set the operating
           system's notion of the window size.

       ·   if the “-c” option is enabled, the backspace, interrupt and line
           kill characters (among many other things) are set

       ·   unless the “-I” option is enabled, the terminal and tab
           initialization strings are sent to the standard error output, and
           @TSET@ waits one second (in case a hardware reset was issued).

       ·   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.

   reset - reinitialization
       When invoked as @RESET@, @TSET@ sets the terminal modes to “sane”

       ·   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.  Also,
       rather than using the terminal initialization strings, it uses the
       terminal reset strings.

       The @RESET@ command is useful after a program dies leaving a terminal
       in an abnormal state:

       ·   you may have to type


           (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.

OPTIONS         top

       The options are as follows:

       -c   Set control characters and modes.

       -e   Set the erase character to ch.

       -I   Do not send the terminal or tab initialization strings to the

       -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
            section TERMINAL TYPE MAPPING for more information.

       -Q   Do not display any values for the erase, interrupt and line kill
            characters.  Normally @TSET@ displays the values for control
            characters which differ from the system's default values.

       -q   The terminal type is displayed to the standard output, and the
            terminal is not initialized in any way.  The option “-” by
            itself is equivalent but archaic.

       -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 SETTING THE ENVIRONMENT for 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(3X).
            Normally this has no effect, unless setupterm is not able to
            detect the window size.

       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”.

       If neither -c or -w is given, both options are assumed.


       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 csh, otherwise, they are for sh.  Note, the csh
       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 ... `


       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 it is often desirable to provide information about the
       type of terminal used on such ports.

       The -m options maps 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 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 :?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 -m option argument be placed within single quote
       characters, and that csh users insert a backslash character (“\”)
       before any exclamation marks (“!”).

HISTORY         top

       A reset command appeared in 2BSD (April 1979), written by Kurt
       Shoens.  This program set the erase and kill characters to ^H
       (backspace) and @ respectively.  Mark Horton improved that in 3BSD
       (October 1979), adding intr, quit, start/stop and eof characters as
       well as changing the program to avoid modifying any user settings.

       Later in 4.1BSD (December 1980), Mark Horton added a call to the tset
       program using the -I and -Q options, i.e., using that to improve the
       terminal modes.  With those options, that version of reset did not
       use the termcap database.

       A separate tset command was provided in 2BSD by Eric Allman.  While
       the oldest published source (from 1979) provides both tset and reset,
       Allman's comments in the 2BSD source code indicate that he began work
       in October 1977, continuing development over the next few years.

       In September 1980, Eric Allman modified tset, adding the code from
       the existing “reset” feature when tset was invoked as reset.  Rather
       than simply copying the existing program, in this merged version,
       tset used the termcap database to do additional (re)initialization of
       the terminal.  This version appeared in 4.1cBSD, late in 1982.

       Other developers (e.g., Keith Bostic and Jim Bloom) continued to
       modify tset until 4.4BSD was released in 1993.

       The ncurses implementation was lightly adapted from the 4.4BSD
       sources for a terminfo environment by Eric S. Raymond


       Neither IEEE Std 1003.1/The Open Group Base Specifications Issue 7
       (POSIX.1-2008) nor X/Open Curses Issue 7 documents @TSET@ or @RESET@.

       The AT&T tput utility (AIX, HPUX, Solaris) incorporated the terminal-
       mode manipulation as well as termcap-based features such as resetting
       tabstops from tset in BSD (4.1c), presumably with the intention of
       making tset obsolete.  However, each of those systems still provides
       tset.  In fact, the commonly-used reset utility is always an alias
       for tset.

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

       A few options are different because the TERMCAP variable is no longer
       supported under terminfo-based ncurses:

       ·   The -S option of BSD tset no longer works; it prints an error
           message to the standard error and dies.

       ·   The -s option only sets TERM, not TERMCAP.

       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 the terminal to use upper-case only.  This feature has
       been omitted.

       The -A, -E, -h, -u and -v options were deleted from the @TSET@
       utility in 4.4BSD.  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
       -a, -d, and -p options are therefore omitted from the usage summary

       Very old systems, e.g., 3BSD, used a different terminal driver which
       was replaced in 4BSD in the early 1980s.  To accommodate these older
       systems, the 4BSD @TSET@ provided a -n option to specify that the new
       terminal driver should be used.  This implementation does not provide
       that choice.

       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.

       As of 4.4BSD, 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 -c and -w options are not found in earlier implementations.
       However, a different window size-change feature was provided in

       ·   In 4.4BSD, tset uses the window size from the termcap description
           to set the window size if tset is not able to obtain the window
           size from the operating system.

       ·   In ncurses, @TSET@ obtains the window size using setupterm, which
           may be from the operating system, the LINES and COLUMNS
           environment variables or the terminal description.

       Obtaining the window size from the terminal description is common to
       both implementations, but considered obsolescent.  Its only practical
       use is for hardware terminals.  Generally speaking, a window size
       would be unset only if there were some problem obtaining the value
       from the operating system (and setupterm would still fail).  For that
       reason, the LINES and COLUMNS environment variables may be useful for
       working around window-size problems.  Those have the drawback that if
       the window is resized, those variables must be recomputed and
       reassigned.  To do this more easily, use the resize(1) program.

ENVIRONMENT         top

       The @TSET@ command uses these environment variables:

            tells @TSET@ whether to initialize TERM using sh or csh syntax.

       TERM Denotes your terminal type.  Each terminal type is distinct,
            though many are similar.

            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 looking for the terminal

FILES         top

            system port name to terminal type mapping database (BSD versions

            terminal capability database

SEE ALSO         top

       csh(1), sh(1), stty(1), curs_terminfo(3X), tty(4), terminfo(5),
       ttys(5), environ(7)

       This describes ncurses version @NCURSES_MAJOR@.@NCURSES_MINOR@ (patch

COLOPHON         top

       This page is part of the ncurses (new curses) project.  Information
       about the project can be found at 
       ⟨https://www.gnu.org/software/ncurses/ncurses.html⟩.  If you have a
       bug report for this manual page, send it to
       bug-ncurses-request@gnu.org.  This page was obtained from the
       project's upstream Git mirror of the CVS repository
       ⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2020-09-18.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-08-17.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to man-pages@man7.org


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