vasilito
ff4ff35918
Red Bear OS is a full fork. All sources must be available from git clone with zero network access. Removed gitignore rules that excluded fetched source trees under recipes/*/source/, local/recipes/kde/*/source/, local/recipes/qt/*/source/, and vendor source trees. Build artifacts (target/, build/, source.tar, *.o, *.so) remain excluded. 127291 files added — kernel, relibc, base, bootloader, pkgar, all KDE/Qt frameworks, mesa, wayland, DRM drivers, and every other recipe source.
189 lines
6.3 KiB
Groff
189 lines
6.3 KiB
Groff
.\"***************************************************************************
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.\" Copyright 2018-2024,2025 Thomas E. Dickey *
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.\" Copyright 1998-2016,2017 Free Software Foundation, Inc. *
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.\" *
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.\" Permission is hereby granted, free of charge, to any person obtaining a *
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.\" copy of this software and associated documentation files (the *
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.\" "Software"), to deal in the Software without restriction, including *
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.\" without limitation the rights to use, copy, modify, merge, publish, *
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.\" distribute, distribute with modifications, sublicense, and/or sell *
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.\" copies of the Software, and to permit persons to whom the Software is *
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.\" furnished to do so, subject to the following conditions: *
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.\" *
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.\" The above copyright notice and this permission notice shall be included *
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.\" in all copies or substantial portions of the Software. *
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.\" *
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.\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
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.\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
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.\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
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.\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
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.\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
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.\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
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.\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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.\" *
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.\" Except as contained in this notice, the name(s) of the above copyright *
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.\" holders shall not be used in advertising or otherwise to promote the *
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.\" sale, use or other dealings in this Software without prior written *
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.\" authorization. *
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.\"***************************************************************************
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.\"
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.\" $Id: clear.1,v 1.53 2025/04/05 21:56:26 tom Exp $
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.TH @CLEAR@ 1 2025-04-05 "ncurses @NCURSES_MAJOR@.@NCURSES_MINOR@" "User commands"
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.ie \n(.g \{\
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.ds `` \(lq
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.ds '' \(rq
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.ds ' \(aq
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.\}
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.el \{\
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.ie t .ds `` ``
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.el .ds `` ""
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.ie t .ds '' ''
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.el .ds '' ""
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.ie t .ds ' \(aq
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.el .ds ' '
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.\}
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.
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.de bP
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.ie n .IP \(bu 4
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.el .IP \(bu 2
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..
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.
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.SH NAME
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\fB\%@CLEAR@\fP \-
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clear the terminal screen
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.SH SYNOPSIS
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.B @CLEAR@
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.RB [ \-x ]
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.RB [ \-T\ \c
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.IR terminal-type ]
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.PP
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.B "@CLEAR@ \-V"
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.SH DESCRIPTION
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\fB\%@CLEAR@\fP clears your terminal's screen and its scrollback buffer,
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if any.
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\fB\%@CLEAR@\fP retrieves the terminal type from the environment
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variable \fITERM\fP,
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then consults the \fIterminfo\fP terminal capability database entry for
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that type to determine how to perform these actions.
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.PP
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The capabilities to clear the screen and scrollback buffer are named
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\*(``clear\*('' and \*(``E3\*('', respectively.
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The latter is a \fIuser-defined capability\fP,
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applying an extension mechanism introduced in \fI\%ncurses\fP 5.0
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(1999).
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.SH OPTIONS
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\fB\%@CLEAR@\fP recognizes the following options.
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.TP 9 \" "-T type" + 2n
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.B \-T \fItype\fP
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produces instructions suitable for the terminal \fItype\fP.
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Normally,
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this option is unnecessary,
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because the terminal type is inferred from the environment variable
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\fITERM\fP.
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If this option is specified,
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\fB\%@CLEAR@\fP ignores the environment variables \fILINES\fP and
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\fI\%COLUMNS\fP as well.
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.TP
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.B \-V
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reports the version of \fI\%ncurses\fP associated with this program and
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exits with a successful status.
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.TP
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.B \-x
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prevents \fB\%@CLEAR@\fP from attempting to clear the scrollback buffer.
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.SH PORTABILITY
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Neither IEEE Std 1003.1/The Open Group Base Specifications Issue\ 7
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(POSIX.1-2008) nor X/Open Curses Issue\ 7 documents \fB\%@CLEAR@\fP.
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.PP
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The latter documents \fBtput\fP,
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which could be used to replace this utility either via a shell script or
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by an alias
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(such as a symbolic link)
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to run \fB\%@TPUT@\fP as \fB\%@CLEAR@\fP.
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.SH HISTORY
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A \fBclear\fP command using the \fItermcap\fP database and library
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appeared in 2BSD (1979).
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.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=2BSD/src/clear.c
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Eighth Edition Unix (1985) later included it.
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.PP
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The commercial Unix arm of AT&T adapted a different BSD program
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(\fBtset\fP) to make a new command,
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\fBtput\fP,
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and replaced the \fBclear\fP program with a shell script that called
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\*(``\fBtput clear\fP\*(''.
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.PP
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.RS 4
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.EX
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.nf
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/usr/bin/tput ${1:+\-T$1} clear 2> /dev/null
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exit
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.fi
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.EE
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.RE
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.PP
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In 1989, when Keith Bostic revised the BSD \fBtput\fP command
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to make it similar to AT&T's \fBtput\fP,
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he added a \fBclear\fP shell script as well.
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.\" https://minnie.tuhs.org/cgi-bin/utree.pl?file=Net2/usr/src/usr.bin/\
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.\" tput/clear.sh
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.PP
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.RS 4
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.EX
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exec tput clear
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.EE
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.RE
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.PP
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The remainder of the script in each case is a copyright notice.
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.PP
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In 1995,
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\fI\%ncurses\fP's \fBclear\fP began by adapting BSD's original
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\fBclear\fP command to use \fIterminfo\fP.
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The \fBE3\fP extension came later.
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.bP
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In June 1999, \fIxterm\fP provided an extension to the standard control
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sequence for clearing the screen.
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Rather than clearing just the visible part of the screen using
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.RS 8
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.PP
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.EX
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printf \*'\e033[2J\*'
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.EE
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.RE
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.IP
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one could clear the scrollback buffer as well by using
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.RS 8
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.PP
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.EX
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printf \*'\e033[\fB3\fPJ\*'
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.EE
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.RE
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.IP
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instead.
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\*(``XTerm Control Sequences\fP\*('' documents this feature as
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originating with \fIxterm\fP.
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.bP
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A few other terminal emulators adopted it,
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such as PuTTY in 2006.
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.bP
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In April 2011, a Red Hat developer submitted a patch to the Linux
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kernel, modifying its console driver to do the same thing.
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Documentation of this change,
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appearing in Linux 3.0,
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did not mention \fIxterm\fP,
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although that program was cited in the Red Hat bug report (#683733)
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motivating the feature.
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.bP
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Subsequently,
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more terminal developers adopted the feature.
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The next relevant step was to change the \fI\%ncurses\fP \fBclear\fP
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program in 2013 to incorporate this extension.
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.bP
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In 2013,
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the \fBE3\fP capability was not exercised by
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\*(``\fB\%@TPUT@ clear\fP\*(''.
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That oversight was addressed in 2016 by reorganizing \fB\%@TPUT@\fP to
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share its logic with \fB\%@CLEAR@\fP and \fB\%@TSET@\fP.
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.SH SEE ALSO
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\fB\%@TPUT@\fP(1),
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\fB\%xterm\fP(1),
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\fB\%terminfo\fP(5)
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