+</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>.