NAME

       clear - clear the terminal screen

SYNOPSIS

       clear [-Ttype] [-V] [-x]

DESCRIPTION

       clear  clears  your  screen  if  this  is possible, including its scrollback buffer (if the extended “E3”
       capability is defined).  clear looks in the environment for the terminal type given  by  the  environment
       variable TERM, and then in the terminfo database to determine how to clear the screen.

       clear  writes  to  the  standard  output.  You can redirect the standard output to a file (which prevents
       clear from actually clearing the screen), and later cat the file to  the  screen,  clearing  it  at  that
       point.

OPTIONS

       -T type
            indicates  the  type of terminal.  Normally this option is unnecessary, because the default is taken
            from the environment variable TERM.  If -T is specified, then the shell variables LINES and  COLUMNS
            will also be ignored.

       -V   reports  the  version  of  ncurses  which  was  used in this program, and exits.  The options are as
            follows:

       -x   do not attempt to clear the terminal's scrollback buffer using the extended “E3” capability.

HISTORY

       A clear command appeared in 2.79BSD dated February 24, 1979.  Later that was provided in Unix 8th edition
       (1985).

       AT&T  adapted  a  different BSD program (tset) to make a new command (tput), and used this to replace the
       clear command with a shell script which calls tput clear, e.g.,

           /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 the AT&T tput, he  added  a
       shell script for the clear command:

           exec tput clear

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

       The  ncurses  clear  command  began in 1995 by adapting the original BSD clear command (with terminfo, of
       course).

       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 using

               printf '\033[3J'

           This is documented in XTerm Control Sequences as a feature originating with xterm.

       •   A few other terminal developers adopted the feature, e.g., 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.  The Linux change, part of the  3.0  release,  did  not  mention  xterm,
           although it was cited in the Red Hat bug report (#683733) which led to the change.

       •   Again,  a few other terminal developers adopted the feature.  But the next relevant step was a change
           to the clear program in 2013 to incorporate this extension.

       •   In 2013, the E3 extension was overlooked in tput with the “clear” parameter.  That was  addressed  in
           2016 by reorganizing tput to share its logic with clear and tset.

PORTABILITY

       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 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.

SEE ALSO

       tput(1), terminfo(5)

       This describes ncurses version 6.1 (patch 20180127).

                                                                                                        clear(1)