TSET(1)                                                                TSET(1)


NAME
       tset - terminal dependent initialization

SYNOPSIS
       tset [ options ] [ -m [ident][test baudrate]:type ] ... [ type ]

       reset [ options ] [ -m [ident][test baudrate]:type ] ... [ type ]

DESCRIPTION
       Tset  sets up your terminal when you first log in to a UNIX system.  It
       does terminal dependent processing such as setting erase and kill char‐
       acters,  setting  or  resetting delays, sending any sequences needed to
       properly initialized the terminal, and the like.  It  first  determines
       the  type of terminal involved, and then does necessary initializations
       and mode settings.  The type of terminal attached to each UNIX port  is
       specified  in  the /etc/ttys(5) database.  Type names for terminals may
       be found in the termcap(5) database.  If a port  is  not  wired  perma‐
       nently  to  a  specific  terminal  (not  hardwired) it will be given an
       appropriate generic identifier such as dialup.

       In the case where no arguments are specified,  tset  simply  reads  the
       terminal  type  out of the environment variable TERM and re-initializes
       the terminal.  The rest of this manual concerns itself  with  mode  and
       environment  initialization,  typically done once at login, and options
       used at initialization time to determine the terminal type and  set  up
       terminal modes.

       When  used  in a startup script (.profile for sh(1) users or .login for
       csh(1) users) it is desirable to give information  about  the  type  of
       terminal  you will usually use on ports which are not hardwired.  These
       ports are identified in /etc/ttys as dialup or  plugboard  or  arpanet,
       etc.  To specify what terminal type you usually use on these ports, the
       -m (map) option flag is followed by the appropriate port  type  identi‐
       fier, an optional baud rate specification, and the terminal type.  (The
       effect is to ‘‘map’’ from some conditions to a terminal type, that  is,
       to tell tset ‘‘If I’m on this kind of port, guess that I’m on that kind
       of terminal’’.)  If more than  one  mapping  is  specified,  the  first
       applicable  mapping  prevails.   A missing port type identifier matches
       all identifiers.  Any of the alternate generic names given  in  termcap
       may be used for the identifier.

       A baudrate is specified as with stty(1), and is compared with the speed
       of the diagnostic output (which should be the control  terminal).   The
       baud  rate  test  may  be  any  combination of: >, @, <, and !; @ means
       ‘‘at’’ and !  inverts the sense of the test.  To  avoid  problems  with
       metacharacters,  it  is  best to place the entire argument to -m within
       ‘‘´’’ characters; users of csh(1) must also  put  a  ‘‘\’’  before  any
       ‘‘!’’ used here.

       Thus

              tset -m ´dialup>300:adm3a´ -m dialup:dw2 -m ´plugboard:?adm3a´

       causes  the terminal type to be set to an adm3a if the port in use is a
       dialup at a speed greater than 300 baud; to a dw2 if the port is  (oth‐
       erwise) a dialup (i.e. at 300 baud or less).  (NOTE: the examples given
       here appear to take up more than one line, for text processing reasons.
       When  you  type  in real tset commands, you must enter them entirely on
       one line.)  If the type finally determined by tset begins with a  ques‐
       tion  mark,  the  user is asked if s/he really wants that type.  A null
       response means to use that type; otherwise, another type can be entered
       which  will be used instead.  Thus, in the above case, the user will be
       queried on a plugboard port as to whether they are  actually  using  an
       adm3a.

       If no mapping applies and a final type option, not preceded by a -m, is
       given on the command line then that type is used;  otherwise  the  type
       found  in the /etc/ttys database will be taken to be the terminal type.
       This should always be the case for hardwired ports.

       It is usually desirable to return the terminal type, as finally  deter‐
       mined  by  tset, and information about the terminal’s capabilities to a
       shell’s environment.  This can be done using the -  option;  using  the
       Bourne shell, sh(1):

              export TERM; TERM=`tset - options...`

       or using the C shell, csh(1):

              setenv TERM `tset - options...`

       With  csh  it is preferable to use the following command in your .login
       file to initialize the TERM and TERMCAP environment  variables  at  the
       same time.

              eval `tset -s options...`

       It is also convenient to make an alias in your .cshrc:

              alias tset ´eval `tset -s \!*`´

       This allows the command:

              tset 2621

       to be invoked at any time to set the terminal and environment.  Note to
       Bourne Shell users: It is not possible to get this aliasing effect with
       a  shell  script,  because  shell scripts cannot set the environment of
       their parent.  (If a process could set its parent’s  environment,  none
       of this nonsense would be necessary in the first place.)

       These  commands  cause  tset  to place the name of your terminal in the
       variable TERM in the environment; see environ(7).

       Once the terminal type is known, tset engages in terminal  driver  mode
       setting.   This normally involves sending an initialization sequence to
       the terminal, setting the single character erase  (and  optionally  the
       line-kill  (full line erase)) characters, and setting special character
       delays.  Tab and newline expansion are turned off  during  transmission
       of the terminal initialization sequence.

       On terminals that can backspace but not overstrike (such as a CRT), and
       when the erase character is the default erase character (‘#’  on  stan‐
       dard systems), the erase character is changed to BACKSPACE (Control-H).

       The options are:

       -ec    set the erase character to be the named character c on all  ter‐
              minals,  the default being the backspace character on the termi‐
              nal, usually ^H.  The character c can either be typed  directly,
              or entered using the hat notation used here.

       -kc    is similar to -e but for the line kill character rather than the
              erase character; c defaults to ^X (for  purely  historical  rea‐
              sons).   The  kill  characters is left alone if -k is not speci‐
              fied.  The hat notation can also be used for this option.

       -ic    is similar to -e but for the interrupt character rather than the
              erase character; c defaults to ^C.  The hat notation can also be
              used for this option.

       -      The name of the terminal finally decided upon is output  on  the
              standard  output.   This is intended to be captured by the shell
              and placed in the environment variable TERM.

       -s     Print the sequence of csh commands to initialize the environment
              variables  TERM  and  TERMCAP  based on the name of the terminal
              finally decided upon.

       -n     On systems with the Berkeley 4BSD tty driver, specifies that the
              new  tty  driver  modes should be initialized for this terminal.
              For a CRT, the CRTERASE and CRTKILL modes are set  only  if  the
              baud rate is 1200 or greater.  See tty(4) for more detail.

       -I     suppresses transmitting terminal initialization strings.

       -Q     suppresses  printing  the  ‘‘Erase  set to’’ and ‘‘Kill set to’’
              messages.

       If tset is invoked as reset, it will set cooked and  echo  modes,  turn
       off cbreak and raw modes, turn on newline translation, and restore spe‐
       cial characters to a sensible state before any terminal dependent  pro‐
       cessing  is  done.   Any  special character that is found to be NULL or
       ‘‘-1’’ is reset to its default value.  All arguments  to  tset  may  be
       used with reset.

       This  is most useful after a program dies leaving a terminal in a funny
       state. You may have to type ‘‘<LF>reset<LF>’’ to get it to  work  since
       <CR> may not work in this state. Often none of this will echo.

EXAMPLES
       These  examples  all  assume the Bourne shell and use the - option.  If
       you use csh, use one of the variations described above.   Note  that  a
       typical use of tset in a .profile or .login will also use the -e and -k
       options, and often the -n or -Q options as well.   These  options  have
       not  been included here to keep the examples small.  (NOTE: some of the
       examples given here appear to take up more than one line, for text pro‐
       cessing  reasons.   When you type in real tset commands, you must enter
       them entirely on one line.)

       At the moment, you are on a 2621.  This is suitable for typing by  hand
       but not for a .profile, unless you are always on a 2621.

              export TERM; TERM=`tset - 2621`

       You  have an h19 at home which you dial up on, but your office terminal
       is hardwired and known in /etc/ttys.

              export TERM; TERM=`tset - -m dialup:h19`

       You have a switch which connects everything to  everything,  making  it
       nearly  impossible to key on what port you are coming in on.  You use a
       vt100 in your office at 9600 baud, and dial up to switch ports at  1200
       baud  from home on a 2621.  Sometimes you use someone elses terminal at
       work, so you want it to ask you to make sure  what  terminal  type  you
       have  at  high speeds, but at 1200 baud you are always on a 2621.  Note
       the placement of the question mark,  and  the  quotes  to  protect  the
       greater than and question mark from interpretation by the shell.

              export   TERM;   TERM=`tset   -   -m   ’switch>1200:?vt100’   -m
              ’switch<=1200:2621’

       All of the above entries will fall back on the terminal type  specified
       in  /etc/ttys  if  none of the conditions hold.  The following entry is
       appropriate if you always dial up, always at the  same  baud  rate,  on
       many  different  kinds  of  terminals.  Your most common terminal is an
       adm3a.  It always asks you what kind of terminal you are on, defaulting
       to adm3a.

              export TERM; TERM=`tset - .PP If the file /etc/ttys is not prop‐
              erly installed and you want to key entirely on  the  baud  rate,
              the following can be used:

              export TERM; TERM=`tset - -m ’>1200:vt100’ 2621`

       Here  is  a  fancy example to illustrate the power of tset and to hope‐
       lessly confuse anyone who has made it this far.  You dial  up  at  1200
       baud or less on a concept100, sometimes over switch ports and sometimes
       over regular dialups.  You use various terminals at speeds higher  than
       1200  over  switch ports, most often the terminal in your office, which
       is a vt100.  However, sometimes you log in from the university you used
       to go to, over the ARPANET; in this case you are on an ALTO emulating a
       dm2500.  You also often log in on various hardwired ports, such as  the
       console, all of which are properly entered in /etc/ttys.  You want your
       erase character set to control H, your kill character set to control U,
       and  don’t want tset to print the ‘‘Erase set to Backspace, Kill set to
       Control U’’ message.

              export TERM; TERM=`tset  -e  -k^U  -Q  -  -m  ’switch<=1200:con‐
              cept100’    -m    ’switch:?vt100’    -m   dialup:concept100   -m
              arpanet:dm2500`

FILES
       /etc/ttys port name to terminal type mapping database
       /etc/termcap   terminal capability database

SEE ALSO
       csh(1), sh(1), stty(1), ttys(5), termcap(5), environ(7)

BUGS
       The tset command is one of the first commands a user must  master  when
       getting started on a UNIX system.  Unfortunately, it is one of the most
       complex, largely because of the extra effort the user must  go  through
       to  get  the environment of the login shell set.  Something needs to be
       done to make all this simpler, either the login(1)  program  should  do
       this  stuff,  or  a default shell alias should be made, or a way to set
       the environment of the parent should exist.

       This program can’t intuit personal choices  for  erase,  interrupt  and
       line  kill characters, so it leaves these set to the local system stan‐
       dards.


4th Berkeley Distribution         May 5, 1986                          TSET(1)
 
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