+</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>