X-Git-Url: http://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=doc%2Fhtml%2Fman%2Fclear.1.html;h=74b53fdc670bac6f876f7373d5664c4584df21ac;hp=fad1c2072bb27a5aa511101172a19843ac473f7c;hb=5461fc336d03fbfea6b85ac21c6d49c528f6752d;hpb=b1f61d9f3aa244512045a6b02e759825d7049d34 diff --git a/doc/html/man/clear.1.html b/doc/html/man/clear.1.html index fad1c207..74b53fdc 100644 --- a/doc/html/man/clear.1.html +++ b/doc/html/man/clear.1.html @@ -1,74 +1,167 @@ + + +
+ + +- - --
- clear - clear the terminal screen - - --
- clear - - --
- 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. - - --
- tput(1), terminfo(5) - - - - +clear(1) 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 actu- + ally 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 environ- + ment 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: + 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. +
+ 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. +
+ tput(1), terminfo(5) + This describes ncurses version 6.0 (patch 20161231). + clear(1)-