-<!--
+<!--
****************************************************************************
- * Copyright (c) 1998-2010,2013 Free Software Foundation, Inc. *
+ * Copyright 2018,2020 Thomas E. Dickey *
+ * Copyright 1998-2016,2017 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the *
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: clear.1,v 1.10 2013/06/22 22:22:11 tom Exp @
+ * @Id: clear.1,v 1.23 2020/02/02 23:34:34 tom Exp @
+ * these would be fallbacks for DS/DE,
+ * but groff changed the meaning of the macros.
-->
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-<TITLE>clear 1</TITLE>
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+<meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
+<TITLE>@CLEAR@ 1</TITLE>
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-<H1 class="no-header">clear 1</H1>
+<H1 class="no-header">@CLEAR@ 1</H1>
<PRE>
-<STRONG><A HREF="clear.1.html">clear(1)</A></STRONG> <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>
+<B><A HREF="clear.1.html">clear(1)</A></B> General Commands Manual <B><A HREF="clear.1.html">clear(1)</A></B>
-</PRE>
-<H2><a name="h2-NAME">NAME</a></H2><PRE>
- <STRONG>clear</STRONG> - clear the terminal screen
+</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
+ <B>clear</B> - clear the terminal screen
-</PRE>
-<H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
- <STRONG>clear</STRONG>
+</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
+ <B>clear</B> [<B>-T</B><I>type</I>] [<B>-V</B>] [<B>-x</B>]
-</PRE>
-<H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
- <STRONG>clear</STRONG> clears your screen if this is possible, including
- its scrollback buffer (if the extended "E3" capability is
- defined). <STRONG>clear</STRONG> looks in the environment for the terminal
- type and then in the <STRONG>terminfo</STRONG> database to determine how to
- clear the screen.
+</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
+ <B>clear</B> clears your screen if this is possible, including its scrollback
+ buffer (if the extended "E3" capability is defined). <B>clear</B> looks in
+ the environment for the terminal type given by the environment variable
+ <B>TERM</B>, and then in the <B>terminfo</B> database to determine how to clear the
+ screen.
- <STRONG>clear</STRONG> ignores any command-line parameters that may be
- present.
+ <B>clear</B> writes to the standard output. You can redirect the standard
+ output to a file (which prevents <B>clear</B> from actually clearing the
+ screen), and later <B>cat</B> the file to the screen, clearing it at that
+ point.
-</PRE>
-<H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
- <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
+</PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
+ <B>-T</B> <I>type</I>
+ indicates the <I>type</I> of terminal. Normally this option is
+ unnecessary, because the default is taken from the environment
+ variable <B>TERM</B>. If <B>-T</B> is specified, then the shell variables <B>LINES</B>
+ and <B>COLUMNS</B> will also be ignored.
+
+ <B>-V</B> reports the version of ncurses which was used in this program, and
+ exits. The options are as follows:
+
+ <B>-x</B> do not attempt to clear the terminal's scrollback buffer using the
+ extended "E3" capability.
+
+
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ A <B>clear</B> 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 (<B>tset</B>) to make a new command
+ (<B>tput</B>), and used this to replace the <B>clear</B> command with a shell script
+ which calls <B>tput</B> <B>clear</B>, e.g.,
+
+ /usr/bin/tput ${1:+-T$1} clear 2> /dev/null
+ exit
+
+ In 1989, when Keith Bostic revised the BSD <B>tput</B> command to make it
+ similar to the AT&T <B>tput</B>, he added a shell script for the <B>clear</B>
+ command:
+
+ exec tput clear
+
+ The remainder of the script in each case is a copyright notice.
+
+ The ncurses <B>clear</B> command began in 1995 by adapting the original BSD
+ <B>clear</B> command (with terminfo, of course).
+
+ The <B>E3</B> extension came later:
+
+ <B>o</B> 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 <I>scrollback</I> using
+
+ printf '\033[<B>3</B>J'
+
+ This is documented in <I>XTerm</I> <I>Control</I> <I>Sequences</I> as a feature
+ originating with xterm.
+
+ <B>o</B> A few other terminal developers adopted the feature, e.g., PuTTY in
+ 2006.
+
+ <B>o</B> 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.
+
+ <B>o</B> Again, a few other terminal developers adopted the feature. But
+ the next relevant step was a change to the <B>clear</B> program in 2013 to
+ incorporate this extension.
+
+ <B>o</B> In 2013, the <B>E3</B> extension was overlooked in <B>tput</B> with the "clear"
+ parameter. That was addressed in 2016 by reorganizing <B>tput</B> to
+ share its logic with <B>clear</B> and <B>tset</B>.
+
+
+</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
+ 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 <B>tput</B>, which could be used to replace this utility
+ either via a shell script or by an alias (such as a symbolic link) to
+ run <B>tput</B> as <B>clear</B>.
+
+
+</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
+ <B><A HREF="tput.1.html">tput(1)</A></B>, <B><A HREF="terminfo.5.html">terminfo(5)</A></B>
- This describes <STRONG>ncurses</STRONG> version 6.0 (patch 20150905).
+ This describes <B>ncurses</B> version 6.2 (patch 20210612).
- <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>
+ <B><A HREF="clear.1.html">clear(1)</A></B>
</PRE>
<div class="nav">
<ul>
<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
+<li><a href="#h2-OPTIONS">OPTIONS</a></li>
+<li><a href="#h2-HISTORY">HISTORY</a></li>
+<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>