229 lines
6.4 KiB
Groff
229 lines
6.4 KiB
Groff
.\" Copyright (c) 1980, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)intro.3 8.1 (Berkeley) 6/4/93
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.\"
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.sh 1 Usage
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.pp
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This is a description of how to actually use the screen package.
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For simplicity, we assume all updating, reading, etc.
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is applied to
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.Vn stdscr ,
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although a different window can of course be specified.
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.sh 2 "Initialization"
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.pp
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In order to use the screen package,
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the routines must know about terminal characteristics,
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and the space for
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.Vn curscr
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and
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.Vn stdscr
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must be allocated.
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These functions are performed by
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.Fn initscr .
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Since it must allocate space for the windows,
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it can overflow core when attempting to do so.
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On this rather rare occasion,
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.Fn initscr
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returns ERR.
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.Fn Initscr
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must
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.bi always
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be called before any of the routines which affect windows are used.
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If it is not,
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the program will core dump as soon as either
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.Vn curscr
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or
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.Vn stdscr
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are referenced.
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However, it is usually best to wait to call it
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until after you are sure you will need it,
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like after checking for startup errors.
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Terminal status changing routines
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like
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.Fn nl
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and
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.Fn cbreak
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should be called after
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.Fn initscr .
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.pp
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After the initial window allocation done by
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.Fn initscr ,
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specific window characteristics can be set.
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Scrolling can be enabled by calling
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.Fn scrollok .
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If you want the cursor to be left after the last change, use
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.Fn leaveok .
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If this isn't done,
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.Fn refresh
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will move the cursor to the window's current \*y after updating it.
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Additional windows can be created by using the functions
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.Fn newwin
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and
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.Fn subwin .
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.Fn Delwin
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allows you to delete an exisiting window.
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The variables
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.Vn LINES
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and
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.Vn COLS
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control the size of the terminal. They are initially implicitly set by
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.Fn initscr ,
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but can be altered explicitly by the user followed by a call to
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.Fn initscr .
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Note that any call to
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.Fn initscr ,
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will always delete any existing
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.Vn stdscr
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and/or
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.Vn curscr
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before creating new ones so this change is best done before the initial call to
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.Fn initscr .
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.pp
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.sh 2 "Output"
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.pp
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The basic functions
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used to change what will go on a window are
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.Fn addch
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and
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.Fn move .
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.Fn Addch
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adds a character at the current \*y,
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returning ERR if it would cause the window to illegally scroll,
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.i i.e. ,
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printing a character in the lower right-hand corner
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of a terminal which automatically scrolls
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if scrolling is not allowed.
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.Fn Move
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changes the current \*y to whatever you want them to be.
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It returns ERR if you try to move off the window.
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As mentioned above, you can combine the two into
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.Fn mvaddch
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to do both things in one call.
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.pp
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The other output functions
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(such as
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.Fn addstr
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and
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.Fn printw )
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all call
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.Fn addch
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to add characters to the window.
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.pp
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After a change has been made to the window,
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you must call
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.Fn refresh .
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when you want the portion of the terminal covered by the window
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to reflect the change.
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In order to optimize finding changes,
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.Fn refresh
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assumes that any part of the window not changed
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since the last
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.Fn refresh
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of that window has not been changed on the terminal,
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.i i.e. ,
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that you have not refreshed a portion of the terminal
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with an overlapping window.
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If this is not the case,
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the routines
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.Fn touchwin ,
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.Fn touchline ,
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and
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.Fn touchoverlap
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are provided to make it look like a desired part of window has been changed,
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thus forcing
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.Fn refresh
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to check that whole subsection of the terminal for changes.
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.pp
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If you call
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.Fn wrefresh
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with
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.Vn curscr ,
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it will make the screen look like the image of
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.Vn curscr .
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This is useful for implementing a command
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which would redraw the screen in case it got messed up.
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.sh 2 Input
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.pp
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Input is essentially a mirror image of output.
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The complementary function to
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.Fn addch
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is
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.Fn getch
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which,
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if echo is set,
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will call
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.Fn addch
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to echo the character.
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Since the screen package needs to know what is on the terminal at all times,
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if characters are to be echoed,
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the tty must be in raw or cbreak mode.
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If it is not,
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.Fn getch
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sets it to be cbreak,
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and then reads in the character.
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.sh 2 "Termination"
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.pp
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In order to perform certain optimizations,
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and,
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on some terminals,
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to work at all,
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some things must be done
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before the screen routines start up.
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These functions are performed in
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.Fn getttmode
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and
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.Fn setterm ,
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which are called by
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.Fn initscr .
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In order to clean up after the routines,
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the routine
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.Fn endwin
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is provided.
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It restores tty modes to what they were
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when
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.Fn initscr
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was first called.
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The terminal state module uses the variable
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.Vn curses_termios
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to save the original terminal state which is then restored upon a call to
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.Fn endwin .
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Thus,
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anytime after the call to initscr,
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.Fn endwin
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should be called before exiting. Note however, that
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.Fn endwin
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should always be called
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.b before
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the final calls to
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.Fn delwin ,
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which free the storage of the windows.
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