X-Git-Url: https://ncurses.scripts.mit.edu/?a=blobdiff_plain;f=doc%2Fhtml%2Fman%2Fclear.1.html;h=528a60bccc986ba8074fd7b4c3c376529095eeb4;hb=67327e4e3b2121f8273fb73ec14ef234ed01231e;hp=405d47ca29764eed4fc504933d5ee96b5676bdb1;hpb=eccca377f55c70b12e3e92621d94d1e1c1fcfb7d;p=ncurses.git diff --git a/doc/html/man/clear.1.html b/doc/html/man/clear.1.html index 405d47ca..528a60bc 100644 --- a/doc/html/man/clear.1.html +++ b/doc/html/man/clear.1.html @@ -1,6 +1,7 @@ -
--clear(1) General Commands Manual clear(1) +clear(1) User commands clear(1) @@ -52,107 +54,104 @@
- clear [-Ttype] [-V] [-x] + clear [-x] [-T terminal-type] + + clear -V
- 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 clears your terminal's screen and its scrollback buffer, if any. + clear retrieves the terminal type from the environment variable TERM, + then consults the terminfo terminal capability database entry for that + type to determine how to perform these actions. - 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. + The capabilities to clear the screen and scrollback buffer are named + "clear" and "E3", respectively. The latter is a user-defined + capability, applying an extension mechanism introduced in ncurses 5.0 + (1999).
- -T type - indicates the type of terminal. Normally this option is unneces- - sary, because the default is taken from the environment variable - TERM. If -T is specified, then the shell variables LINES and COL- - UMNS will also be ignored. + clear recognizes the following options. + + -T type produces instructions suitable for the terminal type. + Normally, this option is unnecessary, because the terminal + type is inferred from the environment variable TERM. If this + option is specified, clear ignores the environment variables + LINES and COLUMNS as well. + + -V reports the version of ncurses associated with this program + and exits with a successful status. + + -x prevents clear from attempting to clear the scrollback buffer. + - -V reports the version of ncurses which was used in this program, and - exits. The options are as follows: +
+ Neither IEEE Std 1003.1/The Open Group Base Specifications Issue 7 + (POSIX.1-2008) nor X/Open Curses Issue 7 documents clear. - -x do not attempt to clear the terminal's scrollback buffer using the - extended "E3" capability. + 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.
- A clear command appeared in 2.79BSD dated February 24, 1979. Later - that was provided in Unix 8th edition (1985). + A clear command using the termcap database and library appeared in 2BSD + (1979). Eighth Edition Unix (1985) later included it. - 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., + The commercial Unix arm of AT&T adapted a different BSD program (tset) + to make a new command, tput, and replaced the clear program with a + shell script that called "tput clear". /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: + In 1989, when Keith Bostic revised the BSD tput command to make it + similar to AT&T's tput, he added a clear shell script as well. 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 1995, ncurses's clear began by adapting BSD's original clear command + to use terminfo. The E3 extension came later. - o In June 1999, xterm provided an extension to the standard control + 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 + one could clear the scrollback buffer as well by using printf '\033[3J' - This is documented in XTerm Control Sequences as a feature origi- - nating with xterm. + instead. "XTerm Control Sequences" documents this feature as + originating with xterm. - o A few other terminal developers adopted the feature, e.g., PuTTY in - 2006. + o A few other terminal emulators adopted it, such as 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 In April 2011, a Red Hat developer submitted a patch to the Linux + kernel, modifying its console driver to do the same thing. + Documentation of this change, appearing in Linux 3.0, did not + mention xterm, although that program was cited in the Red Hat bug + report (#683733) motivating the feature. - 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 Subsequently, more terminal developers adopted the feature. The + next relevant step was to change the ncurses 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. + o In 2013, the E3 capability was not exercised by "tput clear". That + oversight was addressed in 2016 by reorganizing tput to share its + logic with clear and tset.
- tput(1), terminfo(5) - - This describes ncurses version 6.1 (patch 20190121). + tput(1), xterm(1), terminfo(5) - clear(1) +ncurses 6.4 2023-12-16 clear(1)