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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="sd_pid_get_session">
<refentryinfo>
<title>sd_pid_get_session</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_pid_get_session</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_pid_get_session</refname>
<refname>sd_pid_get_unit</refname>
<refname>sd_pid_get_owner_uid</refname>
<refpurpose>Determine session, service or owner of a session of a specific PID</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_pid_get_session</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char** <parameter>session</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_unit</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>char** <parameter>unit</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
<paramdef>pid_t <parameter>pid</parameter></paramdef>
<paramdef>uid_t* <parameter>uid</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_pid_get_session()</function> 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. The returned string
needs to be freed with the libc
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para><function>sd_pid_get_unit()</function> may be
used to determine the systemd unit (i.e. system
service) identifier of a process identified by the
specified process identifier. The unit name is a short
string, suitable for usage in file system paths. Note
that not all processes are part of a unit/service
(e.g. user processes, or kernel threads). For
processes not being part of a systemd unit/system
service this function will fail. The returned string
needs to be freed with the libc
<citerefentry><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
call after use.</para>
<para><function>sd_pid_get_owner_uid()</function> 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
<function>sd_pid_get_session()</function> will
fail. For processes not being part of a login session
and not being a shared process of a user this function
will fail.</para>
<para>If the <literal>pid</literal> paramater of any
of these functions is passed as 0 the operation is
executed for the calling process.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success these calls return 0 or a positive
integer. On failure, these calls return a negative
errno-style error code.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The <function>sd_pid_get_session()</function>,
<function>sd_pid_get_pid()</function>, and
<function>sd_pid_get_owner_uid()</function> interfaces
are available as shared library, which can be compiled
and linked to with the
<literal>libsystemd-login</literal>
<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
<para>Note that the login session identifier as
returned by <function>sd_pid_get_session()</function>
is completely unrelated to the process session
identifier as returned by
<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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