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<p class='location'>Trait CommandExt</p><div class="block items"><ul><li><a href="#required-methods">Required Methods</a></li><li><a href="#implementors">Implementors</a></li></ul></div><p class='location'><a href='../../../index.html'>std</a>::<wbr><a href='../../index.html'>os</a>::<wbr><a href='../index.html'>unix</a>::<wbr><a href='index.html'>process</a></p><script>window.sidebarCurrent = {name: 'CommandExt', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Trait <a href='../../../index.html'>std</a>::<wbr><a href='../../index.html'>os</a>::<wbr><a href='../index.html'>unix</a>::<wbr><a href='index.html'>process</a>::<wbr><a class="trait" href=''>CommandExt</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
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</span><a class='srclink' href='../../../../src/std/sys/unix/ext/process.rs.html#23-94' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait CommandExt {
fn <a href='#tymethod.uid' class='fnname'>uid</a>(&mut self, id: <a class="primitive" href="../../../primitive.u32.html">u32</a>) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a>;
fn <a href='#tymethod.gid' class='fnname'>gid</a>(&mut self, id: <a class="primitive" href="../../../primitive.u32.html">u32</a>) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a>;
fn <a href='#tymethod.before_exec' class='fnname'>before_exec</a><F>(&mut self, f: F) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a><br> <span class="where">where<br> F: <a class="trait" href="../../../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>() -> <a class="type" href="../../../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../../../primitive.tuple.html">()</a>> + <a class="trait" href="../../../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + <a class="trait" href="../../../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a> + 'static</span>;
fn <a href='#tymethod.exec' class='fnname'>exec</a>(&mut self) -> <a class="struct" href="../../../../std/io/struct.Error.html" title="struct std::io::Error">Error</a>;
}</pre><div class='docblock'><p>Unix-specific extensions to the <code>std::process::Command</code> builder</p>
</div>
<h2 id='required-methods'>Required Methods</h2>
<div class='methods'>
<h3 id='tymethod.uid' class='method'><span id='uid.v' class='invisible'><code>fn <a href='#tymethod.uid' class='fnname'>uid</a>(&mut self, id: <a class="primitive" href="../../../primitive.u32.html">u32</a>) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a></code></span></h3><div class='docblock'><p>Sets the child process's user id. This translates to a
<code>setuid</code> call in the child process. Failure in the <code>setuid</code>
call will cause the spawn to fail.</p>
</div><h3 id='tymethod.gid' class='method'><span id='gid.v' class='invisible'><code>fn <a href='#tymethod.gid' class='fnname'>gid</a>(&mut self, id: <a class="primitive" href="../../../primitive.u32.html">u32</a>) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a></code></span></h3><div class='docblock'><p>Similar to <code>uid</code>, but sets the group id of the child process. This has
the same semantics as the <code>uid</code> field.</p>
</div><h3 id='tymethod.before_exec' class='method'><span id='before_exec.v' class='invisible'><code>fn <a href='#tymethod.before_exec' class='fnname'>before_exec</a><F>(&mut self, f: F) -> &mut <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a> <span class="where fmt-newline">where<br> F: <a class="trait" href="../../../../std/ops/trait.FnMut.html" title="trait std::ops::FnMut">FnMut</a>() -> <a class="type" href="../../../../std/io/type.Result.html" title="type std::io::Result">Result</a><<a class="primitive" href="../../../primitive.tuple.html">()</a>> + <a class="trait" href="../../../../std/marker/trait.Send.html" title="trait std::marker::Send">Send</a> + <a class="trait" href="../../../../std/marker/trait.Sync.html" title="trait std::marker::Sync">Sync</a> + 'static, </span></code><div class='since' title='Stable since Rust version 1.15.0'>1.15.0</div></span></h3><div class='docblock'><p>Schedules a closure to be run just before the <code>exec</code> function is
invoked.</p>
<p>The closure is allowed to return an I/O error whose OS error code will
be communicated back to the parent and returned as an error from when
the spawn was requested.</p>
<p>Multiple closures can be registered and they will be called in order of
their registration. If a closure returns <code>Err</code> then no further closures
will be called and the spawn operation will immediately return with a
failure.</p>
<h1 id='notes' class='section-header'><a href='#notes'>Notes</a></h1>
<p>This closure will be run in the context of the child process after a
<code>fork</code>. This primarily means that any modificatons made to memory on
behalf of this closure will <strong>not</strong> be visible to the parent process.
This is often a very constrained environment where normal operations
like <code>malloc</code> or acquiring a mutex are not guaranteed to work (due to
other threads perhaps still running when the <code>fork</code> was run).</p>
<p>When this closure is run, aspects such as the stdio file descriptors and
working directory have successfully been changed, so output to these
locations may not appear where intended.</p>
</div><h3 id='tymethod.exec' class='method'><span id='exec.v' class='invisible'><code>fn <a href='#tymethod.exec' class='fnname'>exec</a>(&mut self) -> <a class="struct" href="../../../../std/io/struct.Error.html" title="struct std::io::Error">Error</a></code><div class='since' title='Stable since Rust version 1.9.0'>1.9.0</div></span></h3><div class='docblock'><p>Performs all the required setup by this <code>Command</code>, followed by calling
the <code>execvp</code> syscall.</p>
<p>On success this function will not return, and otherwise it will return
an error indicating why the exec (or another part of the setup of the
<code>Command</code>) failed.</p>
<p><code>exec</code> not returning has the same implications as calling
<a href="../../../process/fn.exit.html"><code>process::exit</code></a> – no destructors on the current stack or any other
thread’s stack will be run. Therefore, it is recommended to only call
<code>exec</code> at a point where it is fine to not run any destructors. Note,
that the <code>execvp</code> syscall independently guarantees that all memory is
freed and all file descriptors with the <code>CLOEXEC</code> option (set by default
on all file descriptors opened by the standard library) are closed.</p>
<p>This function, unlike <code>spawn</code>, will <strong>not</strong> <code>fork</code> the process to create
a new child. Like spawn, however, the default behavior for the stdio
descriptors will be to inherited from the current process.</p>
<h1 id='notes-1' class='section-header'><a href='#notes-1'>Notes</a></h1>
<p>The process may be in a "broken state" if this function returns in
error. For example the working directory, environment variables, signal
handling settings, various user/group information, or aspects of stdio
file descriptors may have changed. If a "transactional spawn" is
required to gracefully handle errors it is recommended to use the
cross-platform <code>spawn</code> instead.</p>
</div></div>
<h2 id='implementors'>Implementors</h2>
<ul class='item-list' id='implementors-list'>
<li><code>impl CommandExt for <a class="struct" href="../../../../std/process/struct.Command.html" title="struct std::process::Command">Command</a></code></li>
</ul><script type="text/javascript" async
src="../../../../implementors/std/os/unix/process/trait.CommandExt.js">
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