1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="sd_pid_get_session" conditional='HAVE_PAM'>
27 <title>sd_pid_get_session</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>sd_pid_get_session</refentrytitle>
42 <manvolnum>3</manvolnum>
46 <refname>sd_pid_get_session</refname>
47 <refname>sd_pid_get_unit</refname>
48 <refname>sd_pid_get_user_unit</refname>
49 <refname>sd_pid_get_owner_uid</refname>
50 <refname>sd_pid_get_machine_name</refname>
51 <refname>sd_pid_get_slice</refname>
52 <refname>sd_peer_get_session</refname>
53 <refname>sd_peer_get_unit</refname>
54 <refname>sd_peer_get_user_unit</refname>
55 <refname>sd_peer_get_owner_uid</refname>
56 <refname>sd_peer_get_machine_name</refname>
57 <refname>sd_peer_get_slice</refname>
58 <refpurpose>Determine session, service, owner of a
59 session, container/VM or slice of a specific
60 PID or socket peer</refpurpose>
65 <funcsynopsisinfo>#include <systemd/sd-login.h></funcsynopsisinfo>
68 <funcdef>int <function>sd_pid_get_session</function></funcdef>
69 <paramdef>pid_t <parameter>pid</parameter></paramdef>
70 <paramdef>char **<parameter>session</parameter></paramdef>
74 <funcdef>int <function>sd_pid_get_unit</function></funcdef>
75 <paramdef>pid_t <parameter>pid</parameter></paramdef>
76 <paramdef>char **<parameter>unit</parameter></paramdef>
80 <funcdef>int <function>sd_pid_get_user_unit</function></funcdef>
81 <paramdef>pid_t <parameter>pid</parameter></paramdef>
82 <paramdef>char **<parameter>unit</parameter></paramdef>
86 <funcdef>int <function>sd_pid_get_owner_uid</function></funcdef>
87 <paramdef>pid_t <parameter>pid</parameter></paramdef>
88 <paramdef>uid_t *<parameter>uid</parameter></paramdef>
92 <funcdef>int <function>sd_pid_get_machine_name</function></funcdef>
93 <paramdef>pid_t <parameter>pid</parameter></paramdef>
94 <paramdef>char **<parameter>name</parameter></paramdef>
98 <funcdef>int <function>sd_pid_get_slice</function></funcdef>
99 <paramdef>pid_t <parameter>pid</parameter></paramdef>
100 <paramdef>char **<parameter>slice</parameter></paramdef>
104 <funcdef>int <function>sd_peer_get_session</function></funcdef>
105 <paramdef>int <parameter>fd</parameter></paramdef>
106 <paramdef>char **<parameter>session</parameter></paramdef>
110 <funcdef>int <function>sd_peer_get_unit</function></funcdef>
111 <paramdef>int <parameter>fd</parameter></paramdef>
112 <paramdef>char **<parameter>unit</parameter></paramdef>
116 <funcdef>int <function>sd_peer_get_user_unit</function></funcdef>
117 <paramdef>int <parameter>fd</parameter></paramdef>
118 <paramdef>char **<parameter>unit</parameter></paramdef>
122 <funcdef>int <function>sd_peer_get_owner_uid</function></funcdef>
123 <paramdef>int <parameter>fd</parameter></paramdef>
124 <paramdef>uid_t *<parameter>uid</parameter></paramdef>
128 <funcdef>int <function>sd_peer_get_machine_name</function></funcdef>
129 <paramdef>int <parameter>fd</parameter></paramdef>
130 <paramdef>char **<parameter>name</parameter></paramdef>
134 <funcdef>int <function>sd_peer_get_slice</function></funcdef>
135 <paramdef>int <parameter>fd</parameter></paramdef>
136 <paramdef>char **<parameter>slice</parameter></paramdef>
142 <title>Description</title>
144 <para><function>sd_pid_get_session()</function> may be used to
145 determine the login session identifier of a process identified by
146 the specified process identifier. The session identifier is a
147 short string, suitable for usage in file system paths. Note that
148 not all processes are part of a login session (e.g. system service
149 processes, user processes that are shared between multiple
150 sessions of the same user, or kernel threads). For processes not
151 being part of a login session this function will fail with
152 -ENXIO. The returned string needs to be freed with the libc
154 project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
155 call after use.</para>
157 <para><function>sd_pid_get_unit()</function> may be used to
158 determine the systemd system unit (i.e. system service) identifier
159 of a process identified by the specified PID. The unit name is a
160 short string, suitable for usage in file system paths. Note that
161 not all processes are part of a system unit/service (e.g. user
162 processes, or kernel threads). For processes not being part of a
163 systemd system unit this function will fail with -ENXIO (More
164 specifically: this call will not work for processes that are part
165 of user units, use <function>sd_pid_get_user_unit()</function> for
166 that.) The returned string needs to be freed with the libc
168 project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
169 call after use.</para>
171 <para><function>sd_pid_get_user_unit()</function> may be used to
172 determine the systemd user unit (i.e. user service) identifier of
173 a process identified by the specified PID. This is similar to
174 <function>sd_pid_get_unit()</function> but applies to user units
175 instead of system units.</para>
177 <para><function>sd_pid_get_owner_uid()</function> may be used to
178 determine the Unix user identifier of the owner of the session of
179 a process identified the specified PID. Note that this function
180 will succeed for user processes which are shared between multiple
181 login sessions of the same user, where
182 <function>sd_pid_get_session()</function> will fail. For processes
183 not being part of a login session and not being a shared process
184 of a user this function will fail with -ENXIO.</para>
186 <para><function>sd_pid_get_machine_name()</function> may be used
187 to determine the name of the VM or container is a member of. The
188 machine name is a short string, suitable for usage in file system
189 paths. The returned string needs to be freed with the libc
191 project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
192 call after use. For processes not part of a VM or containers this
193 function fails with -ENXIO.</para>
195 <para><function>sd_pid_get_slice()</function> may be used to
196 determine the slice unit the process is a member of. See
197 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
198 for details about slices. The returned string needs to be freed
200 <citerefentry project='man-pages'><refentrytitle>free</refentrytitle><manvolnum>3</manvolnum></citerefentry>
201 call after use.</para>
203 <para>If the <varname>pid</varname> parameter of any of these
204 functions is passed as 0, the operation is executed for the
205 calling process.</para>
207 <para>The <function>sd_peer_get_session()</function>,
208 <function>sd_peer_get_unit()</function>,
209 <function>sd_peer_get_user_unit()</function>,
210 <function>sd_peer_get_owner_uid()</function>,
211 <function>sd_peer_get_machine_name()</function> and
212 <function>sd_peer_get_slice()</function> calls operate similar to
213 their PID counterparts, but operate on a connected AF_UNIX socket
214 and retrieve information about the connected peer process.</para>
218 <title>Return Value</title>
220 <para>On success, these calls return 0 or a positive integer. On
221 failure, these calls return a negative errno-style error
226 <title>Errors</title>
228 <para>Returned errors may indicate the following problems:</para>
233 <term><constant>-ENXIO</constant></term>
235 <listitem><para>Given field is not specified for the described
236 process or peer.</para>
241 <term><constant>-ESRCH</constant></term>
243 <listitem><para>The specified PID does not refer to a running
249 <term><constant>-ENOMEM</constant></term>
251 <listitem><para>Memory allocation failed.</para></listitem>
259 <para>The <function>sd_pid_get_session()</function>,
260 <function>sd_pid_get_unit()</function>,
261 <function>sd_pid_get_user_unit()</function>,
262 <function>sd_pid_get_owner_uid()</function>,
263 <function>sd_pid_get_machine_name()</function>,
264 <function>sd_pid_get_slice()</function>,
265 <function>sd_peer_get_session()</function>,
266 <function>sd_peer_get_unit()</function>,
267 <function>sd_peer_get_user_unit()</function>,
268 <function>sd_peer_get_owner_uid()</function>,
269 <function>sd_peer_get_machine_name()</function> and
270 <function>sd_peer_get_slice()</function> interfaces are
271 available as a shared library, which can be compiled
272 and linked to with the
273 <constant>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
276 <para>Note that the login session identifier as
277 returned by <function>sd_pid_get_session()</function>
278 is completely unrelated to the process session
279 identifier as returned by
280 <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>.</para>
284 <title>See Also</title>
287 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
288 <citerefentry><refentrytitle>sd-login</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
289 <citerefentry><refentrytitle>sd_session_is_active</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
290 <citerefentry><refentrytitle>getsid</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
291 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
292 <citerefentry><refentrytitle>systemd-machined.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>