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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 and then in the terminfo database to determine how to
       clear the screen.

       clear  ignores  any  command-line  parameters  that may be
       present.


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:

       o   In June 1999, xterm provided an extension to the stan-
           dard 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.

       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 exten-
           sion.

       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  Specifica-
       tions  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 20161203).



                                                               clear(1)