2 ****************************************************************************
3 * Copyright (c) 1998-2017,2018 Free Software Foundation, Inc. *
5 * Permission is hereby granted, free of charge, to any person obtaining a *
6 * copy of this software and associated documentation files (the *
7 * "Software"), to deal in the Software without restriction, including *
8 * without limitation the rights to use, copy, modify, merge, publish, *
9 * distribute, distribute with modifications, sublicense, and/or sell *
10 * copies of the Software, and to permit persons to whom the Software is *
11 * furnished to do so, subject to the following conditions: *
13 * The above copyright notice and this permission notice shall be included *
14 * in all copies or substantial portions of the Software. *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
19 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
20 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
21 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
22 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
24 * Except as contained in this notice, the name(s) of the above copyright *
25 * holders shall not be used in advertising or otherwise to promote the *
26 * sale, use or other dealings in this Software without prior written *
28 ****************************************************************************
29 * @Id: clear.1,v 1.22 2018/07/28 21:45:40 tom Exp @
30 * these would be fallbacks for DS/DE,
31 * but groff changed the meaning of the macros.
33 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
36 <meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
37 <meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
38 <TITLE>clear 1</TITLE>
39 <link rel="author" href="mailto:bug-ncurses@gnu.org">
40 <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
43 <H1 class="no-header">clear 1</H1>
45 <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG> General Commands Manual <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>
50 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
51 <STRONG>clear</STRONG> - clear the terminal screen
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>clear</STRONG> [<STRONG>-T</STRONG><EM>type</EM>] [<STRONG>-V</STRONG>] [<STRONG>-x</STRONG>]
58 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
59 <STRONG>clear</STRONG> clears your screen if this is possible, including its scrollback
60 buffer (if the extended "E3" capability is defined). <STRONG>clear</STRONG> looks in
61 the environment for the terminal type given by the environment variable
62 <STRONG>TERM</STRONG>, and then in the <STRONG>terminfo</STRONG> database to determine how to clear the
65 <STRONG>clear</STRONG> writes to the standard output. You can redirect the standard
66 output to a file (which prevents <STRONG>clear</STRONG> from actually clearing the
67 screen), and later <STRONG>cat</STRONG> the file to the screen, clearing it at that
71 </PRE><H2><a name="h2-OPTIONS">OPTIONS</a></H2><PRE>
72 <STRONG>-T</STRONG> <EM>type</EM>
73 indicates the <EM>type</EM> of terminal. Normally this option is unneces-
74 sary, because the default is taken from the environment variable
75 <STRONG>TERM</STRONG>. If <STRONG>-T</STRONG> is specified, then the shell variables <STRONG>LINES</STRONG> and <STRONG>COL-</STRONG>
76 <STRONG>UMNS</STRONG> will also be ignored.
78 <STRONG>-V</STRONG> reports the version of ncurses which was used in this program, and
79 exits. The options are as follows:
81 <STRONG>-x</STRONG> do not attempt to clear the terminal's scrollback buffer using the
82 extended "E3" capability.
85 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
86 A <STRONG>clear</STRONG> command appeared in 2.79BSD dated February 24, 1979. Later
87 that was provided in Unix 8th edition (1985).
89 AT&T adapted a different BSD program (<STRONG>tset</STRONG>) to make a new command
90 (<STRONG>tput</STRONG>), and used this to replace the <STRONG>clear</STRONG> command with a shell script
91 which calls <STRONG>tput</STRONG> <STRONG>clear</STRONG>, e.g.,
93 /usr/bin/tput ${1:+-T$1} clear 2> /dev/null
96 In 1989, when Keith Bostic revised the BSD <STRONG>tput</STRONG> command to make it sim-
97 ilar to the AT&T <STRONG>tput</STRONG>, he added a shell script for the <STRONG>clear</STRONG> command:
101 The remainder of the script in each case is a copyright notice.
103 The ncurses <STRONG>clear</STRONG> command began in 1995 by adapting the original BSD
104 <STRONG>clear</STRONG> command (with terminfo, of course).
106 The <STRONG>E3</STRONG> extension came later:
108 <STRONG>o</STRONG> In June 1999, xterm provided an extension to the standard control
109 sequence for clearing the screen. Rather than clearing just the
110 visible part of the screen using
114 one could clear the <EM>scrollback</EM> using
116 printf '\033[<STRONG>3</STRONG>J'
118 This is documented in <EM>XTerm</EM> <EM>Control</EM> <EM>Sequences</EM> as a feature origi-
121 <STRONG>o</STRONG> A few other terminal developers adopted the feature, e.g., PuTTY in
124 <STRONG>o</STRONG> In April 2011, a Red Hat developer submitted a patch to the Linux
125 kernel, modifying its console driver to do the same thing. The
126 Linux change, part of the 3.0 release, did not mention xterm,
127 although it was cited in the Red Hat bug report (#683733) which led
130 <STRONG>o</STRONG> Again, a few other terminal developers adopted the feature. But
131 the next relevant step was a change to the <STRONG>clear</STRONG> program in 2013 to
132 incorporate this extension.
134 <STRONG>o</STRONG> In 2013, the <STRONG>E3</STRONG> extension was overlooked in <STRONG>tput</STRONG> with the "clear"
135 parameter. That was addressed in 2016 by reorganizing <STRONG>tput</STRONG> to
136 share its logic with <STRONG>clear</STRONG> and <STRONG>tset</STRONG>.
139 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
140 Neither IEEE Std 1003.1/The Open Group Base Specifications Issue 7
141 (POSIX.1-2008) nor X/Open Curses Issue 7 documents tset or reset.
143 The latter documents <STRONG>tput</STRONG>, which could be used to replace this utility
144 either via a shell script or by an alias (such as a symbolic link) to
145 run <STRONG>tput</STRONG> as <STRONG>clear</STRONG>.
148 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
149 <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
151 This describes <STRONG>ncurses</STRONG> version 6.1 (patch 20190921).
155 <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>
159 <li><a href="#h2-NAME">NAME</a></li>
160 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
161 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
162 <li><a href="#h2-OPTIONS">OPTIONS</a></li>
163 <li><a href="#h2-HISTORY">HISTORY</a></li>
164 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
165 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>