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<h4 class="subsection">24.2.8 Signal Messages</h4>

<p><a name="index-signal-messages-2899"></a>
We mentioned above that the shell prints a message describing the signal
that terminated a child process.  The clean way to print a message
describing a signal is to use the functions <code>strsignal</code> and
<code>psignal</code>.  These functions use a signal number to specify which
kind of signal to describe.  The signal number may come from the
termination status of a child process (see <a href="Process-Completion.html#Process-Completion">Process Completion</a>) or it
may come from a signal handler in the same process.

<!-- string.h -->
<!-- GNU -->
<div class="defun">
&mdash; Function: char * <b>strsignal</b> (<var>int signum</var>)<var><a name="index-strsignal-2900"></a></var><br>
<blockquote><p>This function returns a pointer to a statically-allocated string
containing a message describing the signal <var>signum</var>.  You
should not modify the contents of this string; and, since it can be
rewritten on subsequent calls, you should save a copy of it if you need
to reference it later.

        <p><a name="index-string_002eh-2901"></a>This function is a GNU extension, declared in the header file
<samp><span class="file">string.h</span></samp>. 
</p></blockquote></div>

<!-- signal.h -->
<!-- BSD -->
<div class="defun">
&mdash; Function: void <b>psignal</b> (<var>int signum, const char *message</var>)<var><a name="index-psignal-2902"></a></var><br>
<blockquote><p>This function prints a message describing the signal <var>signum</var> to the
standard error output stream <code>stderr</code>; see <a href="Standard-Streams.html#Standard-Streams">Standard Streams</a>.

        <p>If you call <code>psignal</code> with a <var>message</var> that is either a null
pointer or an empty string, <code>psignal</code> just prints the message
corresponding to <var>signum</var>, adding a trailing newline.

        <p>If you supply a non-null <var>message</var> argument, then <code>psignal</code>
prefixes its output with this string.  It adds a colon and a space
character to separate the <var>message</var> from the string corresponding
to <var>signum</var>.

        <p><a name="index-stdio_002eh-2903"></a>This function is a BSD feature, declared in the header file <samp><span class="file">signal.h</span></samp>. 
</p></blockquote></div>

   <p><a name="index-sys_005fsiglist-2904"></a>There is also an array <code>sys_siglist</code> which contains the messages
for the various signal codes.  This array exists on BSD systems, unlike
<code>strsignal</code>.

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