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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_pid_get_session</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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<span style="float:right">systemd 221</span><hr><div class="refentry"><a name="sd_pid_get_session"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_pid_get_session, sd_pid_get_unit, sd_pid_get_user_unit, sd_pid_get_owner_uid, sd_pid_get_machine_name, sd_pid_get_slice, sd_peer_get_session, sd_peer_get_unit, sd_peer_get_user_unit, sd_peer_get_owner_uid, sd_peer_get_machine_name, sd_peer_get_slice — Determine session, service, owner of a
session, container/VM or slice of a specific
PID or socket peer</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-login.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_session</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">session</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_unit</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">unit</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_user_unit</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">unit</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_owner_uid</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>uid_t *<var class="pdparam">uid</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_machine_name</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">name</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_pid_get_slice</b>(</code></td><td>pid_t <var class="pdparam">pid</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">slice</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_session</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">session</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_unit</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">unit</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_user_unit</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">unit</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_owner_uid</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>uid_t *<var class="pdparam">uid</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_machine_name</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">name</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_peer_get_slice</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>char **<var class="pdparam">slice</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm46975811712080"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_pid_get_session()</code> may be used to
determine the login session identifier of a process identified by
the specified process identifier. The session identifier is a
short string, suitable for usage in file system paths. Note that
not all processes are part of a login session (e.g. system service
processes, user processes that are shared between multiple
sessions of the same user, or kernel threads). For processes not
being part of a login session this function will fail with
-ENXIO. The returned string needs to be freed with the libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use.</p><p><code class="function">sd_pid_get_unit()</code> may be used to
determine the systemd system unit (i.e. system service) identifier
of a process identified by the specified PID. The unit name is a
short string, suitable for usage in file system paths. Note that
not all processes are part of a system unit/service (e.g. user
processes, or kernel threads). For processes not being part of a
systemd system unit this function will fail with -ENXIO (More
specifically: this call will not work for processes that are part
of user units, use <code class="function">sd_pid_get_user_unit()</code> for
that.) The returned string needs to be freed with the libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use.</p><p><code class="function">sd_pid_get_user_unit()</code> may be used to
determine the systemd user unit (i.e. user service) identifier of
a process identified by the specified PID. This is similar to
<code class="function">sd_pid_get_unit()</code> but applies to user units
instead of system units.</p><p><code class="function">sd_pid_get_owner_uid()</code> may be used to
determine the Unix user identifier of the owner of the session of
a process identified the specified PID. Note that this function
will succeed for user processes which are shared between multiple
login sessions of the same user, where
<code class="function">sd_pid_get_session()</code> will fail. For processes
not being part of a login session and not being a shared process
of a user this function will fail with -ENXIO.</p><p><code class="function">sd_pid_get_machine_name()</code> may be used
to determine the name of the VM or container is a member of. The
machine name is a short string, suitable for usage in file system
paths. The returned string needs to be freed with the libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use. For processes not part of a VM or containers this
function fails with -ENXIO.</p><p><code class="function">sd_pid_get_slice()</code> may be used to
determine the slice unit the process is a member of. See
<a href="systemd.slice.html"><span class="citerefentry"><span class="refentrytitle">systemd.slice</span>(5)</span></a>
for details about slices. The returned string needs to be freed
with the libc
<a href="http://man7.org/linux/man-pages/man3/free.3.html"><span class="citerefentry"><span class="refentrytitle">free</span>(3)</span></a>
call after use.</p><p>If the <code class="varname">pid</code> parameter of any of these
functions is passed as 0, the operation is executed for the
calling process.</p><p>The <code class="function">sd_peer_get_session()</code>,
<code class="function">sd_peer_get_unit()</code>,
<code class="function">sd_peer_get_user_unit()</code>,
<code class="function">sd_peer_get_owner_uid()</code>,
<code class="function">sd_peer_get_machine_name()</code> and
<code class="function">sd_peer_get_slice()</code> calls operate similar to
their PID counterparts, but operate on a connected AF_UNIX socket
and retrieve information about the connected peer process.</p></div><div class="refsect1"><a name="idm46975811691952"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these calls return 0 or a positive integer. On
failure, these calls return a negative errno-style error
code.</p></div><div class="refsect1"><a name="idm46975811690656"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-ENXIO"><span class="term"><code class="constant">-ENXIO</code></span><a class="headerlink" title="Permalink to this term" href="#-ENXIO">¶</a></dt><dd><p>Given field is not specified for the described
process or peer.</p></dd><dt id="-ESRCH"><span class="term"><code class="constant">-ESRCH</code></span><a class="headerlink" title="Permalink to this term" href="#-ESRCH">¶</a></dt><dd><p>The specified PID does not refer to a running
process.</p></dd><dt id="-ENOMEM"><span class="term"><code class="constant">-ENOMEM</code></span><a class="headerlink" title="Permalink to this term" href="#-ENOMEM">¶</a></dt><dd><p>Memory allocation failed.</p></dd></dl></div></div><div class="refsect1"><a name="idm46975811684640"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The <code class="function">sd_pid_get_session()</code>,
<code class="function">sd_pid_get_unit()</code>,
<code class="function">sd_pid_get_user_unit()</code>,
<code class="function">sd_pid_get_owner_uid()</code>,
<code class="function">sd_pid_get_machine_name()</code>,
<code class="function">sd_pid_get_slice()</code>,
<code class="function">sd_peer_get_session()</code>,
<code class="function">sd_peer_get_unit()</code>,
<code class="function">sd_peer_get_user_unit()</code>,
<code class="function">sd_peer_get_owner_uid()</code>,
<code class="function">sd_peer_get_machine_name()</code> and
<code class="function">sd_peer_get_slice()</code> interfaces are
available as a shared library, which can be compiled
and linked to with the
<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
file.</p><p>Note that the login session identifier as
returned by <code class="function">sd_pid_get_session()</code>
is completely unrelated to the process session
identifier as returned by
<a href="http://man7.org/linux/man-pages/man2/getsid.2.html"><span class="citerefentry"><span class="refentrytitle">getsid</span>(2)</span></a>.</p></div><div class="refsect1"><a name="idm46975811672608"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="sd-login.html"><span class="citerefentry"><span class="refentrytitle">sd-login</span>(3)</span></a>,
<a href="sd_session_is_active.html"><span class="citerefentry"><span class="refentrytitle">sd_session_is_active</span>(3)</span></a>,
<a href="http://man7.org/linux/man-pages/man2/getsid.2.html"><span class="citerefentry"><span class="refentrytitle">getsid</span>(2)</span></a>,
<a href="systemd.slice.html"><span class="citerefentry"><span class="refentrytitle">systemd.slice</span>(5)</span></a>,
<a href="systemd-machined.service.html"><span class="citerefentry"><span class="refentrytitle">systemd-machined.service</span>(8)</span></a>
</p></div></div></body></html>
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