reset



tset(1)                                                                tset(1)




NAME

       tset, reset - terminal initialization


SYNOPSIS

       tset [-IQVqrs] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
       A reset [-IQVqrs] [-] [-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 standard
       error output device in the /etc/ttys file.  (On Linux and System-V-like
       UNIXes,  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 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 stan-
       dard 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 an 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:

       -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.

       -e   Set the erase character to ch.

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

       -Q   Don’t  display  any  values for the erase, interrupt and line kill
            characters.

       -V   reports the version of ncurses which was used in this program, and
            exits.

       -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.

       -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
       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 ... `



TERMINAL TYPE MAPPING

       When the terminal is not hardwired into the system (or the current sys-
       tem 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 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 partic-
       ular 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 opera-
       tor 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 map-
       pings 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 exclama-
       tion marks (‘‘!’’).


HISTORY

       The  tset  command appeared in BSD 3.0.  The ncurses implementation was
       lightly adapted from the 4.4BSD sources for a terminfo  environment  by
       Eric S. Raymond <esr@snark.thyrsus.com>.


COMPATIBILITY

       The  tset utility has been provided 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.

       The  -S  option of BSD tset no longer works; it prints an error message
       to stderr and dies.  The -s option only sets TERM, not  TERMCAP.   Both
       these  changes  are because the TERMCAP variable is no longer supported
       under terminfo-based ncurses, which makes tset -S useless (we  made  it
       die noisily 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  let-
       ter)  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  docu-
       mented  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.  The -adnp options are therefore omitted from the  usage
       summary above.

       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.


ENVIRONMENT

       The tset command uses the SHELL and TERM environment variables.


FILES

       /etc/ttys
            system  port  name to terminal type mapping database (BSD versions
            only).

       /usr/share/terminfo
            terminal capability database


SEE ALSO

       csh(1), sh(1), stty(1), tty(4), termcap(5), ttys(5), environ(7)




                                                                       tset(1)

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