# tset 1

    tset(1)                                                         tset(1)

## 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 - initialization

           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  System-V-like  UNIXes  and systems using that conven-
           tion, 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 termi-
           nal 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  ter-
           minal 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 initializa-
           tion 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 the standard error output.

### reset - reinitialization

           When  invoked  as  reset, tset sets cooked and echo modes,
           turns off cbreak and raw modes, turns on newline  transla-
           tion  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.

## OPTIONS

           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 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 section TERMINAL TYPE MAPPING for more infor-
                mation.

           -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  out-
                put,  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.   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"  nota-
           tion, i.e., control-h may be specified as "^H" or "^h".

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

## 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 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 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 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 specifi-
           cation,  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 applica-
           ble 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  termi-
           nal type is vt100.  The result of this mapping is to spec-
           ify 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

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

## COMPATIBILITY

           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 tset utility has been provided  for  backward-compati-
           bility  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 of 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 begin-
           ning 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 above.

           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 recom-
           mended 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 implementa-
           tions.   However,  a  different window size-change feature
           was provided in 4.4BSD.

           o   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.

           o   In  ncurses,  tset  obtains  the  window  size   using
               setupterm, which may be from the operating system, the
               LINES and COLUMNS environment variables or the  termi-
               nal description.

           Obtaining the window size from the terminal description is
           common to both implementations,  but  considered  obsoles-
           cent.   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 oper-
           ating 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

           The tset command uses these environment variables:

           SHELL
                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.

           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
                looking for the terminal description.

## 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),   curs_terminfo(3x),   tty(4),
           terminfo(5), ttys(5), environ(7)

           This describes ncurses version 6.0 (patch 20160611).

                                                                    tset(1)