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<H1 class="no-header">curs_initscr 3x</H1>
<PRE>
<STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG> <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
<STRONG>initscr</STRONG>, <STRONG>newterm</STRONG>, <STRONG>endwin</STRONG>, <STRONG>isendwin</STRONG>, <STRONG>set_term</STRONG>, <STRONG>delscreen</STRONG> - <STRONG>curses</STRONG> screen
initialization and manipulation routines
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>WINDOW</STRONG> <STRONG>*initscr(void);</STRONG>
<STRONG>int</STRONG> <STRONG>endwin(void);</STRONG>
<STRONG>bool</STRONG> <STRONG>isendwin(void);</STRONG>
<STRONG>SCREEN</STRONG> <STRONG>*newterm(const</STRONG> <STRONG>char</STRONG> <STRONG>*</STRONG><EM>type</EM><STRONG>,</STRONG> <STRONG>FILE</STRONG> <STRONG>*</STRONG><EM>outfd</EM><STRONG>,</STRONG> <STRONG>FILE</STRONG> <STRONG>*</STRONG><EM>infd</EM><STRONG>);</STRONG>
<STRONG>SCREEN</STRONG> <STRONG>*set_term(SCREEN</STRONG> <STRONG>*</STRONG><EM>new</EM><STRONG>);</STRONG>
<STRONG>void</STRONG> <STRONG>delscreen(SCREEN*</STRONG> <EM>sp</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
</PRE><H3><a name="h3-initscr">initscr</a></H3><PRE>
<STRONG>initscr</STRONG> is normally the first <STRONG>curses</STRONG> routine to call when initializing
a program. A few special routines sometimes need to be called before
it; these are <STRONG><A HREF="curs_slk.3x.html">slk_init(3x)</A></STRONG>, <STRONG>filter</STRONG>, <STRONG>ripoffline</STRONG>, <STRONG>use_env</STRONG>. For multiple-
terminal applications, <STRONG>newterm</STRONG> may be called before <STRONG>initscr</STRONG>.
The initscr code determines the terminal type and initializes all <STRONG>curs-</STRONG>
<STRONG>es</STRONG> data structures. <STRONG>initscr</STRONG> also causes the first call to <STRONG><A HREF="curscurs_refresh.3x.html">refresh(3x)</A></STRONG>
to clear the screen. If errors occur, <STRONG>initscr</STRONG> writes an appropriate
error message to standard error and exits; otherwise, a pointer is re-
turned to <STRONG>stdscr</STRONG>.
</PRE><H3><a name="h3-newterm">newterm</a></H3><PRE>
A program that outputs to more than one terminal should use the <STRONG>newterm</STRONG>
routine for each terminal instead of <STRONG>initscr</STRONG>. A program that needs to
inspect capabilities, so it can continue to run in a line-oriented mode
if the terminal cannot support a screen-oriented program, would also
use <STRONG>newterm</STRONG>. The routine <STRONG>newterm</STRONG> should be called once for each termi-
nal. It returns a variable of type <STRONG>SCREEN</STRONG> <STRONG>*</STRONG> which should be saved as a
reference to that terminal. <STRONG>newterm</STRONG>'s arguments are
<STRONG>o</STRONG> the <EM>type</EM> of the terminal to be used in place of <STRONG>$TERM</STRONG>,
<STRONG>o</STRONG> a file pointer for output to the terminal, and
<STRONG>o</STRONG> another file pointer for input from the terminal
If the <EM>type</EM> parameter is <STRONG>NULL</STRONG>, <STRONG>$TERM</STRONG> will be used.
</PRE><H3><a name="h3-endwin">endwin</a></H3><PRE>
The program must also call <STRONG>endwin</STRONG> for each terminal being used before
exiting from <STRONG>curses</STRONG>. If <STRONG>newterm</STRONG> is called more than once for the same
terminal, the first terminal referred to must be the last one for which
<STRONG>endwin</STRONG> is called.
A program should always call <STRONG>endwin</STRONG> before exiting or escaping from
<STRONG>curses</STRONG> mode temporarily. This routine
<STRONG>o</STRONG> resets colors to correspond with the default color pair 0,
<STRONG>o</STRONG> moves the cursor to the lower left-hand corner of the screen,
<STRONG>o</STRONG> clears the remainder of the line so that it uses the default col-
ors,
<STRONG>o</STRONG> sets the cursor to normal visibility (see <STRONG><A HREF="curs_kernel.3x.html">curs_set(3x)</A></STRONG>),
<STRONG>o</STRONG> stops cursor-addressing mode using the <EM>exit</EM><STRONG>_</STRONG><EM>ca</EM><STRONG>_</STRONG><EM>mode</EM> terminal capa-
bility,
<STRONG>o</STRONG> restores tty modes (see <STRONG><A HREF="curs_kernel.3x.html">reset_shell_mode(3x)</A></STRONG>).
Calling <STRONG><A HREF="curs_refresh.3x.html">refresh(3x)</A></STRONG> or <STRONG><A HREF="curs_refresh.3x.html">doupdate(3x)</A></STRONG> after a temporary escape causes the
program to resume visual mode.
</PRE><H3><a name="h3-isendwin">isendwin</a></H3><PRE>
The <STRONG>isendwin</STRONG> routine returns <STRONG>TRUE</STRONG> if <STRONG>endwin</STRONG> has been called without any
subsequent calls to <STRONG>wrefresh</STRONG>, and <STRONG>FALSE</STRONG> otherwise.
</PRE><H3><a name="h3-set_term">set_term</a></H3><PRE>
The <STRONG>set_term</STRONG> routine is used to switch between different terminals.
The screen reference <STRONG>new</STRONG> becomes the new current terminal. The previ-
ous terminal is returned by the routine. This is the only routine
which manipulates <STRONG>SCREEN</STRONG> pointers; all other routines affect only the
current terminal.
</PRE><H3><a name="h3-delscreen">delscreen</a></H3><PRE>
The <STRONG>delscreen</STRONG> routine frees storage associated with the <STRONG>SCREEN</STRONG> data
structure. The <STRONG>endwin</STRONG> routine does not do this, so <STRONG>delscreen</STRONG> should be
called after <STRONG>endwin</STRONG> if a particular <STRONG>SCREEN</STRONG> is no longer needed.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
<STRONG>endwin</STRONG> returns the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> upon successful com-
pletion.
Routines that return pointers always return <STRONG>NULL</STRONG> on error.
X/Open defines no error conditions. In this implementation
<STRONG>o</STRONG> <STRONG>endwin</STRONG> returns an error if the terminal was not initialized.
<STRONG>o</STRONG> <STRONG>newterm</STRONG> returns an error if it cannot allocate the data structures
for the screen, or for the top-level windows within the screen,
i.e., <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, or <STRONG>stdscr</STRONG>.
<STRONG>o</STRONG> <STRONG>set_term</STRONG> returns no error.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
These functions were described in the XSI Curses standard, Issue 4. As
of 2015, the current document is X/Open Curses, Issue 7.
</PRE><H3><a name="h3-Differences">Differences</a></H3><PRE>
X/Open specifies that portable applications must not call <STRONG>initscr</STRONG> more
than once:
<STRONG>o</STRONG> The portable way to use <STRONG>initscr</STRONG> is once only, using <STRONG>refresh</STRONG> (see
<STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>) to restore the screen after <STRONG>endwin</STRONG>.
<STRONG>o</STRONG> This implementation allows using <STRONG>initscr</STRONG> after <STRONG>endwin</STRONG>.
Old versions of curses, e.g., BSD 4.4, may have returned a null pointer
from <STRONG>initscr</STRONG> when an error is detected, rather than exiting. It is
safe but redundant to check the return value of <STRONG>initscr</STRONG> in XSI Curses.
</PRE><H3><a name="h3-Unset-TERM-Variable">Unset TERM Variable</a></H3><PRE>
If the TERM variable is missing or empty, <STRONG>initscr</STRONG> uses the value "un-
known", which normally corresponds to a terminal entry with the <EM>generic</EM>
(<EM>gn</EM>) capability. Generic entries are detected by <STRONG>setupterm</STRONG> (see
<STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>) and cannot be used for full-screen operation. Other
implementations may handle a missing/empty TERM variable differently.
</PRE><H3><a name="h3-Signal-Handlers">Signal Handlers</a></H3><PRE>
Quoting from X/Open Curses, section 3.1.1:
<EM>Curses</EM> <EM>implementations</EM> <EM>may</EM> <EM>provide</EM> <EM>for</EM> <EM>special</EM> <EM>handling</EM> <EM>of</EM> <EM>the</EM>
<STRONG>SIGINT</STRONG><EM>,</EM> <STRONG>SIGQUIT</STRONG> <EM>and</EM> <STRONG>SIGTSTP</STRONG> <EM>signals</EM> <EM>if</EM> <EM>their</EM> <EM>disposition</EM> <EM>is</EM>
<STRONG>SIG_DFL</STRONG> <EM>at</EM> <EM>the</EM> <EM>time</EM> <STRONG>initscr</STRONG> <EM>is</EM> <EM>called</EM> <STRONG>...</STRONG>
<EM>Any</EM> <EM>special</EM> <EM>handling</EM> <EM>for</EM> <EM>these</EM> <EM>signals</EM> <EM>may</EM> <EM>remain</EM> <EM>in</EM> <EM>effect</EM> <EM>for</EM>
<EM>the</EM> <EM>life</EM> <EM>of</EM> <EM>the</EM> <EM>process</EM> <EM>or</EM> <EM>until</EM> <EM>the</EM> <EM>process</EM> <EM>changes</EM> <EM>the</EM> <EM>disposi-</EM>
<EM>tion</EM> <EM>of</EM> <EM>the</EM> <EM>signal.</EM>
<EM>None</EM> <EM>of</EM> <EM>the</EM> <EM>Curses</EM> <EM>functions</EM> <EM>are</EM> <EM>required</EM> <EM>to</EM> <EM>be</EM> <EM>safe</EM> <EM>with</EM> <EM>respect</EM>
<EM>to</EM> <EM>signals</EM> ...
This implementation establishes signal handlers during initialization,
e.g., <STRONG>initscr</STRONG> or <STRONG>newterm</STRONG>. Applications which must handle these signals
should set up the corresponding handlers <EM>after</EM> initializing the li-
brary:
<STRONG>SIGINT</STRONG>
The handler <EM>attempts</EM> to cleanup the screen on exit. Although it
<EM>usually</EM> works as expected, there are limitations:
<STRONG>o</STRONG> Walking the <STRONG>SCREEN</STRONG> list is unsafe, since all list management
is done without any signal blocking.
<STRONG>o</STRONG> On systems which have <STRONG>REENTRANT</STRONG> turned on, <STRONG>set_term</STRONG> uses func-
tions which could deadlock or misbehave in other ways.
<STRONG>o</STRONG> <STRONG>endwin</STRONG> calls other functions, many of which use stdio or other
library functions which are clearly unsafe.
<STRONG>SIGTERM</STRONG>
This uses the same handler as <STRONG>SIGINT</STRONG>, with the same limitations.
It is not mentioned in X/Open Curses, but is more suitable for
this purpose than <STRONG>SIGQUIT</STRONG> (which is used in debugging).
<STRONG>SIGTSTP</STRONG>
This handles the <EM>stop</EM> signal, used in job control. When resuming
the process, this implementation discards pending input with
<STRONG>flushinput</STRONG> (see <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>), and repaints the screen assuming
that it has been completely altered. It also updates the saved
terminal modes with <STRONG>def_shell_mode</STRONG> (see <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>).
<STRONG>SIGWINCH</STRONG>
This handles the window-size changes which were ignored in the
standardization efforts. The handler sets a (signal-safe) vari-
able which is later tested in <STRONG>wgetch</STRONG> (see <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>). If
<STRONG>keypad</STRONG> has been enabled for the corresponding window, <STRONG>wgetch</STRONG> re-
turns the key symbol <STRONG>KEY_RESIZE</STRONG>. At the same time, <STRONG>wgetch</STRONG> calls
<STRONG>resizeterm</STRONG> to adjust the standard screen <STRONG>stdscr</STRONG>, and update other
data such as <STRONG>LINES</STRONG> and <STRONG>COLS</STRONG>.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
<STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>, <STRONG><A HREF="curs_slk.3x.html">curs_slk(3x)</A></STRONG>, <STRONG>curs_ter-</STRONG>
<STRONG><A HREF="curs_terminfo.3x.html">minfo(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>.
<STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>
</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>
<ul>
<li><a href="#h3-initscr">initscr</a></li>
<li><a href="#h3-newterm">newterm</a></li>
<li><a href="#h3-endwin">endwin</a></li>
<li><a href="#h3-isendwin">isendwin</a></li>
<li><a href="#h3-set_term">set_term</a></li>
<li><a href="#h3-delscreen">delscreen</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a>
<ul>
<li><a href="#h3-Differences">Differences</a></li>
<li><a href="#h3-Unset-TERM-Variable">Unset TERM Variable</a></li>
<li><a href="#h3-Signal-Handlers">Signal Handlers</a></li>
</ul>
</li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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