# clear 1

    clear(1)                                                              clear(1)

## NAME

           clear - clear the terminal screen

## SYNOPSIS

           clear

## 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.

           clear ignores any command-line parameters that  may  be  present.   The
           analogous  "tput  clear"  has  command-line parameters including -T for
           overriding the TERM environment variable.

## 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 sim-
           ilar 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:

           o   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 origi-
               nating with xterm.

           o   A few other terminal developers adopted the feature, e.g., PuTTY in
               2006.

           o   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.

           o   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.

           o   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 6.0 (patch 20170603).

                                                                          clear(1)