X-Git-Url: http://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff_plain;f=doc%2Fhtml%2Fman%2Fclear.1.html;h=43832ee15b1777b0d85bfb32bb205e826ca3e767;hp=c0608ffb8bbcdf8d84c3494c1961725218f7c60f;hb=HEAD;hpb=59c1a9740d123db3cecafe76e18f7848081a670b diff --git a/doc/html/man/clear.1.html b/doc/html/man/clear.1.html index c0608ffb..a6dbfb60 100644 --- a/doc/html/man/clear.1.html +++ b/doc/html/man/clear.1.html @@ -1,6 +1,7 @@ - - -clear 1 - - + +clear 1 2024-03-16 ncurses 6.4 User commands + + -

clear 1

clear 1 2024-03-16 ncurses 6.4 User commands

-clear(1)                                                       clear(1)
+clear(1)                         User commands                        clear(1)
 
 
 
@@ -50,34 +51,113 @@

SYNOPSIS

-       clear
+       clear [-x] [-T terminal-type]
+
+       clear -V

DESCRIPTION

-       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 and then in the terminfo database to determine how to
-       clear the screen.
+       clear  clears your terminal's screen and its scrollback buffer, if any.
+       clear retrieves the terminal type from the environment  variable  TERM,
+       then  consults the terminfo terminal capability database entry for that
+       type to determine how to perform these actions.
 
-       clear  ignores  any  command-line  parameters  that may be
-       present.
+       The capabilities to clear the screen and scrollback  buffer  are  named
+       "clear"   and   "E3",  respectively.   The  latter  is  a  user-defined
+       capability, applying an extension mechanism introduced in  ncurses  5.0
+       (1999).
 
 
-

OPTIONS

+       clear recognizes the following options.
+
+       -T type  produces   instructions   suitable   for  the  terminal  type.
+                Normally, this option is  unnecessary,  because  the  terminal
+                type  is inferred from the environment variable TERM.  If this
+                option is specified, clear ignores the  environment  variables
+                LINES and COLUMNS as well.
+
+       -V       reports  the  version  of ncurses associated with this program
+                and exits with a successful status.
+
+       -x       prevents clear from attempting to clear the scrollback buffer.
+
+
+

PORTABILITY

+       Neither IEEE Std 1003.1/The Open  Group  Base  Specifications  Issue  7
+       (POSIX.1-2008) nor X/Open Curses Issue 7 documents clear.
+
+       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.
+
+
+

HISTORY

+       A clear command using the termcap database and library appeared in 2BSD
+       (1979).  Eighth Edition Unix (1985) later included it.
+
+       The commercial Unix arm of AT&T adapted a different BSD program  (tset)
+       to  make  a  new  command,  tput, and replaced the clear program with a
+       shell script that called "tput clear".
+
+           /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 AT&T's tput, he added a clear shell script as well.
 
-       This describes ncurses version 6.0 (patch 20160723).
+           exec tput clear
+
+       The remainder of the script in each case is a copyright notice.
+
+       In 1995, ncurses's clear began by adapting BSD's original clear command
+       to use terminfo.  The E3 extension came later.
+
+       o   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 scrollback buffer as well by using
+
+               printf '\033[3J'
+
+           instead.  "XTerm  Control  Sequences"  documents  this  feature  as
+           originating with xterm.
+
+       o   A few other terminal emulators adopted it, such as 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.
+           Documentation  of  this  change,  appearing  in  Linux 3.0, did not
+           mention xterm, although that program was cited in the Red  Hat  bug
+           report (#683733) motivating the feature.
+
+       o   Subsequently,  more  terminal  developers adopted the feature.  The
+           next relevant step was to change the ncurses clear program in  2013
+           to incorporate this extension.
+
+       o   In 2013, the E3 capability was not exercised by "tput clear".  That
+           oversight was addressed in 2016 by reorganizing tput to  share  its
+           logic with clear and tset.
+
+
+