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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

       This program initializes terminals.

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

       o   the standard error,

       o   standard output,

       o   standard input and

       o   ultimately "/dev/tty"

       to obtain terminal settings.  Having retrieved these  set-
       tings,  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 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  -m options maps from some set of conditions to a ter-
       minal type, that is, to tell tset "If I'm on this port  at
       a  particular speed, guess that I'm on that kind of termi-
       nal".

       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

       A reset command appeared in 2BSD (1979), written  by  Kurt
       Shoens.

       A  separate tset command was provided in 2BSD by Eric All-
       man.  While the oldest published source (from  1979)  pro-
       vides  both programs, Allman's comments in the 2BSD source
       code indicate that he began work in October 1977, continu-
       ing development over the next few years.

       In  1980,  Eric  Allman modified tset to provide a "reset"
       feature when the program was invoked as reset.

       The ncurses implementation was lightly  adapted  from  the
       4.4BSD  sources for a terminfo environment by Eric S. Ray-
       mond <esr@snark.thyrsus.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 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 obso-
       lete.  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:

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

       o   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 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 20161203).



                                                                tset(1)