2 ****************************************************************************
3 * Copyright (c) 1998-2013,2016 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 1.14 2016/11/19 21:30:46 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 http://invisible-island.net/scripts/readme.html#others_scripts">
38 <TITLE>clear 1</TITLE>
39 <link rev=made 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> <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>
58 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
59 <STRONG>clear</STRONG> clears your screen if this is possible, including
60 its scrollback buffer (if the extended "E3" capability is
61 defined). <STRONG>clear</STRONG> looks in the environment for the terminal
62 type and then in the <STRONG>terminfo</STRONG> database to determine how to
65 <STRONG>clear</STRONG> ignores any command-line parameters that may be
69 </PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
70 A <STRONG>clear</STRONG> command appeared in 2.79BSD dated February 24,
71 1979. Later that was provided in Unix 8th edition (1985).
73 AT&T adapted a different BSD program (<STRONG>tset</STRONG>) to make a new
74 command (<STRONG>tput</STRONG>), and used this to replace the <STRONG>clear</STRONG> command
75 with a shell script which calls <STRONG>tput</STRONG> <STRONG>clear</STRONG>, e.g.,
76 /usr/bin/tput ${1:+-T$1} clear 2> /dev/null
79 In 1989, when Keith Bostic revised the BSD <STRONG>tput</STRONG> command to
80 make it similar to the AT&T <STRONG>tput</STRONG>, he added a shell script
81 for the <STRONG>clear</STRONG> command:
84 The remainder of the script in each case is a copyright
87 The ncurses <STRONG>clear</STRONG> command began in 1995 by adapting the
88 original BSD <STRONG>clear</STRONG> command (with terminfo, of course).
90 The <STRONG>E3</STRONG> extension came later:
92 <STRONG>o</STRONG> In June 1999, xterm provided an extension to the stan-
93 dard control sequence for clearing the screen. Rather
94 than clearing just the visible part of the screen
98 one could clear the <EM>scrollback</EM> using
99 printf '\033[<STRONG>3</STRONG>J'
101 This is documented in <EM>XTerm</EM> <EM>Control</EM> <EM>Sequences</EM> as a
102 feature originating with xterm.
104 <STRONG>o</STRONG> A few other terminal developers adopted the feature,
107 <STRONG>o</STRONG> In April 2011, a Red Hat developer submitted a patch
108 to the Linux kernel, modifying its console driver to
109 do the same thing. The Linux change, part of the 3.0
110 release, did not mention xterm, although it was cited
111 in the Red Hat bug report (#683733) which led to the
114 <STRONG>o</STRONG> Again, a few other terminal developers adopted the
115 feature. But the next relevant step was a change to
116 the <STRONG>clear</STRONG> program in 2013 to incorporate this exten-
119 <STRONG>o</STRONG> In 2013, the <STRONG>E3</STRONG> extension was overlooked in <STRONG>tput</STRONG> with
120 the "clear" parameter. That was addressed in 2016 by
121 reorganizing <STRONG>tput</STRONG> to share its logic with <STRONG>clear</STRONG> and
122 <STRONG>tset</STRONG>.
125 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
126 Neither IEEE Std 1003.1/The Open Group Base Specifica-
127 tions Issue 7 (POSIX.1-2008) nor X/Open Curses Issue 7
128 documents tset or reset.
130 The latter documents <STRONG>tput</STRONG>, which could be used to replace
131 this utility either via a shell script or by an alias
132 (such as a symbolic link) to run <STRONG>tput</STRONG> as <STRONG>clear</STRONG>.
135 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
136 <STRONG><A HREF="tput.1.html">tput(1)</A></STRONG>, <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>
138 This describes <STRONG>ncurses</STRONG> version 6.0 (patch 20161203).
142 <STRONG><A HREF="clear.1.html">clear(1)</A></STRONG>
146 <li><a href="#h2-NAME">NAME</a></li>
147 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
148 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a></li>
149 <li><a href="#h2-HISTORY">HISTORY</a></li>
150 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
151 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>