Provided by: ncurses-bin_6.3+20220423-2_amd64 bug


       tset, reset - terminal initialization


       tset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]
       reset [-IQVcqrsw] [-] [-e ch] [-i ch] [-k ch] [-m mapping] [terminal]


   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 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 convention,
       getty(8)  does  this  job  by  setting  TERM  according  to  the  type  passed  to  it  by

       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” values:

       •   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.


       The options are as follows:

       -c   Set control characters and modes.

       -e ch
            Set the erase character to ch.

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

       -i ch
            Set the interrupt character to ch.

       -k ch
            Set the line kill character to ch.

       -m mapping
            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(1).  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 (“!”).


       A reset command appeared in 1BSD (March 1978), 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.  That version of reset did not
       use the termcap database.

       A separate tset command was provided in 1BSD by Eric Allman, using the  termcap  database.
       Allman's  comments  in  the  source  code  indicate  that  he  began work in October 1977,
       continuing development over the next few years.

       According to comments in the source code, the tset program was modified in September 1980,
       to  use  logic  copied  from  the 3BSD “reset” when it was invoked as reset.  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

       The  tset  utility  provides  for backward-compatibility with BSD environments (under most
       modern UNIXes, /etc/inittab and getty(8) 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 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 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 4.4BSD.

       •   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

       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.


       The tset command uses these environment variables:

            tells tset whether to initialize TERM using sh(1) or csh(1) 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 description.


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

            terminal capability database


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

       This describes ncurses version 6.3 (patch 20220423).