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<h2 class="title">Execution Operators</h2>
<p class="para">
PHP supports one execution operator: backticks (``). Note that
these are not single-quotes! PHP will attempt to execute the
contents of the backticks as a shell command; the output will be
returned (i.e., it won't simply be dumped to output; it can be
assigned to a variable). Use of the backtick operator is identical
to <span class="function"><a href="function.shell-exec.html" class="function">shell_exec()</a></span>.
<div class="informalexample">
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$output </span><span style="color: #007700">= `</span><span style="color: #DD0000">ls -al</span><span style="color: #007700">`;<br />echo </span><span style="color: #DD0000">"<pre></span><span style="color: #0000BB">$output</span><span style="color: #DD0000"></pre>"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
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</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
The backtick operator is disabled when <a href="ini.sect.safe-mode.html#ini.safe-mode" class="link">safe mode</a> is enabled
or <span class="function"><a href="function.shell-exec.html" class="function">shell_exec()</a></span> is disabled.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Unlike some other languages, backticks cannot be used within
double-quoted strings.
</p>
</p></blockquote>
<p class="para">
See also the manual section on <a href="ref.exec.html" class="link">Program
Execution functions</a>, <span class="function"><a href="function.popen.html" class="function">popen()</a></span>
<span class="function"><a href="function.proc-open.html" class="function">proc_open()</a></span>, and
<a href="features.commandline.html" class="link">Using PHP from the
commandline</a>.
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