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NAME | SYNOPSIS | DESCRIPTION | HISTORY | PORTABILITY | SEE ALSO | COLOPHON |
@CLEAR@(1) General Commands Manual @CLEAR@(1)
@CLEAR@ - clear the terminal screen
@CLEAR@
@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.
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@.
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@.
@TPUT@(1), terminfo(5)
This describes ncurses version @NCURSES_MAJOR@.@NCURSES_MINOR@ (patch
@NCURSES_PATCH@).
This page is part of the ncurses (new curses) project. Information
about the project can be found at
⟨https://www.gnu.org/software/ncurses/ncurses.html⟩. If you have a
bug report for this manual page, send it to
bug-ncurses-request@gnu.org. This page was obtained from the
project's upstream Git mirror of the CVS repository
⟨git://ncurses.scripts.mit.edu/ncurses.git⟩ on 2017-07-05. If you
discover any rendering problems in this HTML version of the page, or
you believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
@CLEAR@(1)
Pages that refer to this page: reset(1), setterm(1)