X-Git-Url: https://ncurses.scripts.mit.edu/?a=blobdiff_plain;ds=sidebyside;f=doc%2Fhtml%2Fman%2Fclear.1.html;h=9b2ae01c8b90a6a95781eb07127d2d96dfbc7455;hb=a6eb34d7fec8170a8715f9e53ca2f96452dd30dd;hp=138806fc487c3b587aef1f999d61916cfce6ca25;hpb=9de646fe8f944e760d453b57e01b866d1d514ad7;p=ncurses.git diff --git a/doc/html/man/clear.1.html b/doc/html/man/clear.1.html index 138806fc..d2d85441 100644 --- a/doc/html/man/clear.1.html +++ b/doc/html/man/clear.1.html @@ -1,7 +1,7 @@ - +
+ +- -clear(1) clear(1) +clear(1) General Commands Manual clear(1) --
+
clear - clear the terminal screen --
- clear +
+ clear [-Ttype] [-V] [-x] --
- clear clears your screen if this is possible. It looks in - the environment for the terminal type and then in the ter- - minfo database to figure out how to clear the screen. +
+ 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 ignores any command-line parameters that may be - present. + 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. --
+
+ -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. + + +
+ 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 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. + + 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. + + +
+ 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 5.9 (patch 20110404). + This describes ncurses version 6.2 (patch 20201219). - clear(1) + clear(1)-