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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>&lt;curses.h&gt;</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(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>slk_init</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 initial-
       izes  all <STRONG>curses</STRONG> data structures.  <STRONG>initscr</STRONG> also causes the
       first call to <STRONG>refresh</STRONG> to clear the screen.  If errors  oc-
       cur,  <STRONG>initscr</STRONG> writes an appropriate error message to stan-
       dard error and exits; otherwise, a pointer is returned  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 ter-
       minal cannot support a screen-oriented program, would also
       use <STRONG>newterm</STRONG>.  The routine <STRONG>newterm</STRONG> should  be  called  once
       for each terminal.  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 es-
       caping from <STRONG>curses</STRONG> mode temporarily.  This routine

       <STRONG>o</STRONG>   restores tty modes,

       <STRONG>o</STRONG>   moves the cursor to the lower left-hand corner of  the
           screen and

       <STRONG>o</STRONG>   resets the terminal into the proper non-visual mode.

       Calling <STRONG>refresh</STRONG> or <STRONG>doupdate</STRONG> after a temporary escape caus-
       es 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 cur-
       rent terminal.  The previous terminal is returned  by  the
       routine.   This  is  the  only  routine  which manipulates
       <STRONG>SCREEN</STRONG> pointers; all other routines affect only  the  cur-
       rent 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 par-
       ticular <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 completion.

       Routines that return pointers always return <STRONG>NULL</STRONG> on error.

       X/Open  defines  no error conditions.  In this implementa-
       tion

       <STRONG>o</STRONG>   <STRONG>endwin</STRONG> returns an error if the terminal was  not  ini-
           tialized.

       <STRONG>o</STRONG>   <STRONG>newterm</STRONG> returns an error if it cannot allocate the da-
           ta 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-NOTES">NOTES</a></H2><PRE>
       Note that <STRONG>initscr</STRONG> and <STRONG>newterm</STRONG> may be macros.


</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 Curs-
       es, 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  "unknown", 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 can-
       not be used for full-screen operation.  Other  implementa-
       tions  may handle a missing/empty TERM variable different-
       ly.


</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>han-</EM>
            <EM>dling</EM>  <EM>of</EM>  <EM>the</EM> <EM>SIGINT,</EM> <EM>SIGQUIT</EM> <EM>and</EM> <EM>SIGTSTP</EM> <EM>signals</EM> <EM>if</EM>
            <EM>their</EM> <EM>disposition</EM> <EM>is</EM> <EM>SIG</EM><STRONG>_</STRONG><EM>DFL</EM> <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>disposition</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  corre-
       sponding handlers <EM>after</EM> initializing the library:

       <STRONG>SIGINT</STRONG>
            The  handler  <EM>attempts</EM> to cleanup the screen on exit.
            Although it <EM>usually</EM> works as expected, there are lim-
            itations:

            <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  functions 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 clear-
                ly 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  dis-
            cards    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 ini-
            tially ignored in the standardization  efforts.   The
            handler  sets a (signal-safe) variable 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><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>, <STRONG>curs_vari-</STRONG>
       <STRONG><A HREF="curs_variables.3x.html">ables(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-NOTES">NOTES</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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