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360 lines
14 KiB
XML
360 lines
14 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="sd_pid_get_session" conditional='HAVE_PAM'>
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<refentryinfo>
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<title>sd_pid_get_session</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>sd_pid_get_session</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>sd_pid_get_session</refname>
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<refname>sd_pid_get_unit</refname>
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<refname>sd_pid_get_user_unit</refname>
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<refname>sd_pid_get_owner_uid</refname>
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<refname>sd_pid_get_machine_name</refname>
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<refname>sd_pid_get_slice</refname>
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<refname>sd_pid_get_user_slice</refname>
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<refname>sd_pid_get_cgroup</refname>
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<refname>sd_peer_get_session</refname>
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<refname>sd_peer_get_unit</refname>
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<refname>sd_peer_get_user_unit</refname>
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<refname>sd_peer_get_owner_uid</refname>
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<refname>sd_peer_get_machine_name</refname>
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<refname>sd_peer_get_slice</refname>
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<refname>sd_peer_get_user_slice</refname>
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<refname>sd_peer_get_cgroup</refname>
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<refpurpose>Determine session, unit, owner of a session,
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container/VM or slice of a specific PID or socket
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peer</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_session</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>session</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_unit</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>uid_t *<parameter>uid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>name</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_slice</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_user_slice</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_pid_get_cgroup</function></funcdef>
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<paramdef>pid_t <parameter>pid</parameter></paramdef>
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<paramdef>char **<parameter>cgroup</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_session</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>session</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_unit</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>unit</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>uid_t *<parameter>uid</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>name</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_slice</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_user_slice</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>slice</parameter></paramdef>
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</funcprototype>
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<funcprototype>
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<funcdef>int <function>sd_peer_get_cgroup</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>char **<parameter>cgroup</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para><function>sd_pid_get_session()</function> may be used to
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determine the login session identifier of a process identified by
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the specified process identifier. The session identifier is a
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short string, suitable for usage in file system paths. Note that
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not all processes are part of a login session (e.g. system service
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processes, user processes that are shared between multiple
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sessions of the same user, or kernel threads). For processes not
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being part of a login session, this function will fail with
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-ENODATA. The returned string needs to be freed with the libc
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<citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_pid_get_unit()</function> may be used to
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determine the systemd system unit (i.e. system service or scope
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unit) identifier of a process identified by the specified PID. The
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unit name is a short string, suitable for usage in file system
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paths. Note that not all processes are part of a system
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unit/service (e.g. user processes, or kernel threads). For
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processes not being part of a systemd system unit, this function
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will fail with -ENODATA. (More specifically, this call will not
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work for kernel threads.) The returned string needs to be freed
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with the libc <citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para><function>sd_pid_get_user_unit()</function> may be used to
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determine the systemd user unit (i.e. user service or scope unit)
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identifier of a process identified by the specified PID. This is
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similar to <function>sd_pid_get_unit()</function>, but applies to
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user units instead of system units.</para>
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<para><function>sd_pid_get_owner_uid()</function> may be used to
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determine the Unix UID (user identifier) of the owner of the
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session of a process identified the specified PID. Note that this
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function will succeed for user processes which are shared between
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multiple login sessions of the same user, whereas
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<function>sd_pid_get_session()</function> will fail. For processes
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not being part of a login session and not being a shared process
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of a user, this function will fail with -ENODATA.</para>
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<para><function>sd_pid_get_machine_name()</function> may be used
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to determine the name of the VM or container is a member of. The
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machine name is a short string, suitable for usage in file system
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paths. The returned string needs to be freed with the libc
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<citerefentry
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project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use. For processes not part of a VM or containers, this
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function fails with -ENODATA.</para>
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<para><function>sd_pid_get_slice()</function> may be used to
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determine the slice unit the process is a member of. See
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<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details about slices. The returned string needs to be freed
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with the libc
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<citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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call after use.</para>
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<para>Similarly, <function>sd_pid_get_user_slice()</function>
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returns the user slice (as managed by the user's systemd instance)
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of a process.</para>
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<para><function>sd_pid_get_cgroup()</function> returns the control
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group path of the specified process, relative to the root of the
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hierarchy. Returns the path without trailing slash, except for
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processes located in the root control group, where "/" is
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returned. To find the actual control group path in the file system,
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the returned path needs to be prefixed with
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<filename>/sys/fs/cgroup/</filename> (if the unified control group
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setup is used), or
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<filename>/sys/fs/cgroup/<replaceable>HIERARCHY</replaceable>/</filename>
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(if the legacy multi-hierarchy control group setup is used).</para>
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<para>If the <varname>pid</varname> parameter of any of these
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functions is passed as 0, the operation is executed for the
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calling process.</para>
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<para>The <function>sd_peer_get_session()</function>,
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<function>sd_peer_get_unit()</function>,
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<function>sd_peer_get_user_unit()</function>,
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<function>sd_peer_get_owner_uid()</function>,
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<function>sd_peer_get_machine_name()</function>,
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<function>sd_peer_get_slice()</function>,
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<function>sd_peer_get_user_slice()</function> and
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<function>sd_peer_get_cgroup()</function> calls operate similar to
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their PID counterparts, but operate on a connected AF_UNIX socket
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and retrieve information about the connected peer process. Note
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that these fields are retrieved via <filename>/proc</filename>,
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and hence are not suitable for authorization purposes, as they are
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subject to races.</para>
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</refsect1>
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<refsect1>
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<title>Return Value</title>
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<para>On success, these calls return 0 or a positive integer. On
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failure, these calls return a negative errno-style error
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code.</para>
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</refsect1>
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<refsect1>
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<title>Errors</title>
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<para>Returned errors may indicate the following problems:</para>
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<variablelist>
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<varlistentry>
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<term><constant>-ESRCH</constant></term>
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<listitem><para>The specified PID does not refer to a running
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process.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-BADF</constant></term>
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<listitem><para>The specified socket file descriptor was
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invalid.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENODATA</constant></term>
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<listitem><para>The given field is not specified for the described
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process or peer.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-EINVAL</constant></term>
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<listitem><para>An input parameter was invalid (out of range,
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or NULL, where that is not accepted).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>-ENOMEM</constant></term>
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<listitem><para>Memory allocation failed.</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Notes</title>
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<para>The <function>sd_pid_get_session()</function>,
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<function>sd_pid_get_unit()</function>,
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<function>sd_pid_get_user_unit()</function>,
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<function>sd_pid_get_owner_uid()</function>,
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<function>sd_pid_get_machine_name()</function>,
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<function>sd_pid_get_slice()</function>,
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<function>sd_pid_get_user_slice()</function>,
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<function>sd_peer_get_session()</function>,
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<function>sd_peer_get_unit()</function>,
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<function>sd_peer_get_user_unit()</function>,
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<function>sd_peer_get_owner_uid()</function>,
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<function>sd_peer_get_machine_name()</function>,
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<function>sd_peer_get_slice()</function> and
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<function>sd_peer_get_user_slice()</function> interfaces are
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available as a shared library, which can be compiled and linked to
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with the <constant>libsystemd</constant> <citerefentry
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project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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file.</para>
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<para>Note that the login session identifier as
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returned by <function>sd_pid_get_session()</function>
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is completely unrelated to the process session
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identifier as returned by
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<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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