clear man page

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 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:

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 20170212).

Referenced By

setterm(1), tabs(1), tput(1).