NAME

       clear - clear the terminal screen

SYNOPSIS

       clear [-x] [-T terminal-type]

       clear -V

DESCRIPTION

       clear  clears  your  terminal's screen and its scrollback buffer, if any.  clear retrieves
       the terminal type from the environment variable TERM, then consults the terminfo  terminal
       capability database entry for that type to determine how to perform these actions.

       The  capabilities  to  clear  the screen and scrollback buffer are named “clear” and “E3”,
       respectively.  The latter is a user-defined capability, applying  an  extension  mechanism
       introduced in ncurses 5.0 (1999).

OPTIONS

       clear recognizes the following options.

       -T type  produces  instructions  suitable for the terminal type.  Normally, this option is
                unnecessary, because the terminal type is inferred from the environment  variable
                TERM.  If this option is specified, clear ignores the environment variables LINES
                and COLUMNS as well.

       -V       reports the version of ncurses associated with this  program  and  exits  with  a
                successful status.

       -x       prevents clear from attempting to clear the scrollback buffer.

PORTABILITY

       Neither  IEEE  Std  1003.1/The  Open  Group Base Specifications Issue 7 (POSIX.1-2008) nor
       X/Open Curses Issue 7 documents clear.

       The latter documents tput, which could be used to replace this utility either via a  shell
       script or by an alias (such as a symbolic link) to run tput as clear.

HISTORY

       A  clear  command  using the termcap database and library appeared in 2BSD (1979).  Eighth
       Edition Unix (1985) later included it.

       The commercial Unix arm of AT&T adapted a different BSD  program  (tset)  to  make  a  new
       command,  tput,  and  replaced  the  clear  program  with a shell script that called “tput
       clear”.

           /usr/bin/tput ${1:+-T$1} clear 2> /dev/null
           exit

       In 1989, when Keith Bostic revised the BSD tput command to make it similar to AT&T's tput,
       he added a clear shell script as well.

           exec tput clear

       The remainder of the script in each case is a copyright notice.

       In  1995,  ncurses's clear began by adapting BSD's original clear command to use terminfo.
       The E3 extension came later.

       •   In June 1999, xterm provided  an  extension  to  the  standard  control  sequence  for
           clearing the screen.  Rather than clearing just the visible part of the screen using

               printf '\033[2J'

           one could clear the scrollback buffer as well by using

               printf '\033[3J'

           instead.  “XTerm Control Sequences” documents this feature as originating with xterm.

       •   A few other terminal emulators adopted it, such as PuTTY in 2006.

       •   In  April  2011,  a Red Hat developer submitted a patch to the Linux kernel, modifying
           its console driver to do the same thing.  Documentation of this change,  appearing  in
           Linux  3.0,  did not mention xterm, although that program was cited in the Red Hat bug
           report (#683733) motivating the feature.

       •   Subsequently, more terminal developers adopted the feature.  The  next  relevant  step
           was to change the ncurses clear program in 2013 to incorporate this extension.

       •   In  2013,  the  E3  capability  was not exercised by “tput clear”.  That oversight was
           addressed in 2016 by reorganizing tput to share its logic with clear and tset.

SEE ALSO

       tput(1), xterm(1), terminfo(5)