sleep - Perldoc Browser

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Returns the integer number of seconds actually slept.</p> <p>EXPR should be a positive integer. If called with a negative integer, <a href="/5.36.2/functions/sleep"><code>sleep</code></a> does not sleep but instead emits a warning, sets $! (<code>errno</code>), and returns zero.</p> <p><code>sleep 0</code> is permitted, but a function call to the underlying platform implementation still occurs, with any side effects that may have. <code>sleep 0</code> is therefore not exactly identical to not sleeping at all.</p> <p>May be interrupted if the process receives a signal such as <code>SIGALRM</code>.</p> <pre><code>eval { local $SIG{ALRM} = sub { die "Alarm!\n" }; sleep; }; die $@ unless $@ eq "Alarm!\n";</code></pre> <p>You probably cannot mix <a href="/5.36.2/functions/alarm"><code>alarm</code></a> and <a href="/5.36.2/functions/sleep"><code>sleep</code></a> calls, because <a href="/5.36.2/functions/sleep"><code>sleep</code></a> is often implemented using <a href="/5.36.2/functions/alarm"><code>alarm</code></a>.</p> <p>On some older systems, it may sleep up to a full second less than what you requested, depending on how it counts seconds. Most modern systems always sleep the full amount. They may appear to sleep longer than that, however, because your process might not be scheduled right away in a busy multitasking system.</p> <p>For delays of finer granularity than one second, the <a href="/5.36.2/Time::HiRes">Time::HiRes</a> module (from CPAN, and starting from Perl 5.8 part of the standard distribution) provides <a href="/5.36.2/Time::HiRes#usleep-(-%24useconds-)"><code>usleep</code></a>. You may also use Perl's four-argument version of <a href="/5.36.2/functions/select"><code>select</code></a> leaving the first three arguments undefined, or you might be able to use the <a href="/5.36.2/functions/syscall"><code>syscall</code></a> interface to access <a href="http://man.he.net/man2/setitimer">setitimer(2)</a> if your system supports it. See <a href="/5.36.2/perlfaq8">perlfaq8</a> for details.</p> <p>See also the <a href="/5.36.2/POSIX">POSIX</a> module's <a href="/5.36.2/POSIX#pause"><code>pause</code></a> function.</p> </dd> </dl> </div> <div id="footer"> <p>Perldoc Browser is maintained by Dan Book (<a href="https://metacpan.org/author/DBOOK">DBOOK</a>). Please contact him via the <a href="https://github.com/Grinnz/perldoc-browser/issues">GitHub issue tracker</a> or <a href="mailto:dbook@cpan.org">email</a> regarding any issues with the site itself, search, or rendering of documentation.</p> <p>The Perl documentation is maintained by the Perl 5 Porters in the development of Perl. Please contact them via the <a href="https://github.com/Perl/perl5/issues">Perl issue tracker</a>, the <a href="https://lists.perl.org/list/perl5-porters.html">mailing list</a>, or <a href="https://kiwiirc.com/client/irc.perl.org/p5p">IRC</a> to report any issues with the contents or format of the documentation.</p> </div> </div> <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.slim.min.js" integrity="sha512-/DXTXr6nQodMUiq+IUJYCt2PPOUjrHJ9wFrqpJ3XkgPNOZVfMok7cRw6CSxyCQxXn6ozlESsSh1/sMCTF1rL/g==" crossorigin="anonymous"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.1/umd/popper.min.js" integrity="sha512-ubuT8Z88WxezgSqf3RLuNi5lmjstiJcyezx34yIU2gAHonIi27Na7atqzUZCOoY4CExaoFumzOsFQ2Ch+I/HCw==" crossorigin="anonymous"></script> <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js" integrity="sha384-B4gt1jrGC7Jh4AgTPSdUtOBvfO8shuf57BaghqFfPlYxofvL8/KUEfYiJOMMV+rV" crossorigin="anonymous"></script> <script src="/js/highlight.pack.js"></script> <script>hljs.highlightAll();</script> </body> </html>

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