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Thomas E. Dickey c3b21f65a2 ncurses 6.0 - patch 20161015 
+ amend internal use of tputs to consistently use the number of lines
  affected, e.g., for insert/delete character operations.  While
  merging terminfo source early in 1995, several descriptions used the
  "*" proportional delay for these operations, prompting a change in
  doupdate.
+ regenerate llib-* files.
+ regenerate HTML manpages.
+ fix several formatting issues with manual pages.
2016-10-16 00:57:24 +00:00

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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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