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00d9ef8560
This adds the boolean RemoveIPC= setting to service, socket, mount and swap units (i.e. all unit types that may invoke processes). if turned on, and the unit's user/group is not root, all IPC objects of the user/group are removed when the service is shut down. The life-cycle of the IPC objects is hence bound to the unit life-cycle. This is particularly relevant for units with dynamic users, as it is essential that no objects owned by the dynamic users survive the service exiting. In fact, this patch adds code to imply RemoveIPC= if DynamicUser= is set. In order to communicate the UID/GID of an executed process back to PID 1 this adds a new "user lookup" socket pair, that is inherited into the forked processes, and closed before the exec(). This is needed since we cannot do NSS from PID 1 due to deadlock risks, However need to know the used UID/GID in order to clean up IPC owned by it if the unit shuts down.
1773 lines
95 KiB
XML
1773 lines
95 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
|
||
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="systemd.exec">
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||
<refentryinfo>
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||
<title>systemd.exec</title>
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||
<productname>systemd</productname>
|
||
|
||
<authorgroup>
|
||
<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>
|
||
</authorgroup>
|
||
</refentryinfo>
|
||
|
||
<refmeta>
|
||
<refentrytitle>systemd.exec</refentrytitle>
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||
<manvolnum>5</manvolnum>
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||
</refmeta>
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||
|
||
<refnamediv>
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<refname>systemd.exec</refname>
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<refpurpose>Execution environment configuration</refpurpose>
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</refnamediv>
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||
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<refsynopsisdiv>
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<para><filename><replaceable>service</replaceable>.service</filename>,
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<filename><replaceable>socket</replaceable>.socket</filename>,
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<filename><replaceable>mount</replaceable>.mount</filename>,
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<filename><replaceable>swap</replaceable>.swap</filename></para>
|
||
</refsynopsisdiv>
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||
|
||
<refsect1>
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||
<title>Description</title>
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||
|
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<para>Unit configuration files for services, sockets, mount
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points, and swap devices share a subset of configuration options
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which define the execution environment of spawned
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processes.</para>
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<para>This man page lists the configuration options shared by
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these four unit types. See
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for the common options of all unit configuration files, and
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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and
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more information on the specific unit configuration files. The
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execution specific configuration options are configured in the
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[Service], [Socket], [Mount], or [Swap] sections, depending on the
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unit type.</para>
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</refsect1>
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||
|
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<refsect1>
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<title>Automatic Dependencies</title>
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<para>A few execution parameters result in additional, automatic
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dependencies to be added.</para>
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<para>Units with <varname>WorkingDirectory=</varname> or
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<varname>RootDirectory=</varname> set automatically gain
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dependencies of type <varname>Requires=</varname> and
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<varname>After=</varname> on all mount units required to access
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the specified paths. This is equivalent to having them listed
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explicitly in <varname>RequiresMountsFor=</varname>.</para>
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<para>Similar, units with <varname>PrivateTmp=</varname> enabled
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automatically get mount unit dependencies for all mounts
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required to access <filename>/tmp</filename> and
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<filename>/var/tmp</filename>.</para>
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<para>Units whose standard output or error output is connected to <option>journal</option>, <option>syslog</option>
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or <option>kmsg</option> (or their combinations with console output, see below) automatically acquire dependencies
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||
of type <varname>After=</varname> on <filename>systemd-journald.socket</filename>.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<variablelist class='unit-directives'>
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<varlistentry>
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<term><varname>WorkingDirectory=</varname></term>
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<listitem><para>Takes a directory path relative to the service's root directory specified by
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<varname>RootDirectory=</varname>, or the special value <literal>~</literal>. Sets the working directory for
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executed processes. If set to <literal>~</literal>, the home directory of the user specified in
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<varname>User=</varname> is used. If not set, defaults to the root directory when systemd is running as a
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system instance and the respective user's home directory if run as user. If the setting is prefixed with the
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<literal>-</literal> character, a missing working directory is not considered fatal. If
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<varname>RootDirectory=</varname> is not set, then <varname>WorkingDirectory=</varname> is relative to the root
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of the system running the service manager. Note that setting this parameter might result in additional
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dependencies to be added to the unit (see above).</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>RootDirectory=</varname></term>
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<listitem><para>Takes a directory path relative to the host's root directory (i.e. the root of the system
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running the service manager). Sets the root directory for executed processes, with the <citerefentry
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project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry> system
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call. If this is used, it must be ensured that the process binary and all its auxiliary files are available in
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the <function>chroot()</function> jail. Note that setting this parameter might result in additional
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dependencies to be added to the unit (see above).</para>
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<para>The <varname>PrivateUsers=</varname> setting is particularly useful in conjunction with
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<varname>RootDirectory=</varname>. For details, see below.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>User=</varname></term>
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<term><varname>Group=</varname></term>
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<listitem><para>Set the UNIX user or group that the processes are executed as, respectively. Takes a single
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user or group name, or numeric ID as argument. If no group is set, the default group of the user is used. This
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setting does not affect commands whose command line is prefixed with <literal>+</literal>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>DynamicUser=</varname></term>
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<listitem><para>Takes a boolean parameter. If set, a UNIX user and group pair is allocated dynamically when the
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unit is started, and released as soon as it is stopped. The user and group will not be added to
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<filename>/etc/passwd</filename> or <filename>/etc/group</filename>, but are managed transiently during
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runtime. The <citerefentry><refentrytitle>nss-systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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glibc NSS module provides integration of these dynamic users/groups into the system's user and group
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databases. The user and group name to use may be configured via <varname>User=</varname> and
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<varname>Group=</varname> (see above). If these options are not used and dynamic user/group allocation is
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enabled for a unit, the name of the dynamic user/group is implicitly derived from the unit name. If the unit
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name without the type suffix qualifies as valid user name it is used directly, otherwise a name incorporating a
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hash of it is used. If a statically allocated user or group of the configured name already exists, it is used
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and no dynamic user/group is allocated. Dynamic users/groups are allocated from the UID/GID range
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61184…65519. It is recommended to avoid this range for regular system or login users. At any point in time
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each UID/GID from this range is only assigned to zero or one dynamically allocated users/groups in
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use. However, UID/GIDs are recycled after a unit is terminated. Care should be taken that any processes running
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as part of a unit for which dynamic users/groups are enabled do not leave files or directories owned by these
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users/groups around, as a different unit might get the same UID/GID assigned later on, and thus gain access to
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these files or directories. If <varname>DynamicUser=</varname> is enabled, <varname>RemoveIPC=</varname> and
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<varname>PrivateTmp=</varname> are implied. This ensures that the lifetime of IPC objects and temporary files
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created by the executed processes is bound to the runtime of the service, and hence the lifetime of the dynamic
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user/group. Since <filename>/tmp</filename> and <filename>/var/tmp</filename> are usually the only
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world-writable directories on a system this ensures that a unit making use of dynamic user/group allocation
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cannot leave files around after unit termination. Use <varname>RuntimeDirectory=</varname> (see below) in order
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to assign a writable runtime directory to a service, owned by the dynamic user/group and removed automatically
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when the unit is terminated. Defaults to off.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SupplementaryGroups=</varname></term>
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<listitem><para>Sets the supplementary Unix groups the
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processes are executed as. This takes a space-separated list
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of group names or IDs. This option may be specified more than
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once, in which case all listed groups are set as supplementary
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groups. When the empty string is assigned, the list of
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supplementary groups is reset, and all assignments prior to
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this one will have no effect. In any way, this option does not
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override, but extends the list of supplementary groups
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configured in the system group database for the
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user. This does not affect commands prefixed with <literal>+</literal>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>RemoveIPC=</varname></term>
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<listitem><para>Takes a boolean parameter. If set, all System V and POSIX IPC objects owned by the user and
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group the processes of this unit are run as are removed when the unit is stopped. This setting only has an
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effect if at least one of <varname>User=</varname>, <varname>Group=</varname> and
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<varname>DynamicUser=</varname> are used. It has no effect on IPC objects owned by the root user. Specifically,
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this removes System V semaphores, as well as System V and POSIX shared memory segments and message queues. If
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multiple units use the same user or group the IPC objects are removed when the last of these units is
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stopped. This setting is implied if <varname>DynamicUser=</varname> is set.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Nice=</varname></term>
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<listitem><para>Sets the default nice level (scheduling
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priority) for executed processes. Takes an integer between -20
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(highest priority) and 19 (lowest priority). See
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<citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for details.</para></listitem>
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</varlistentry>
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||
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||
<varlistentry>
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<term><varname>OOMScoreAdjust=</varname></term>
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||
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||
<listitem><para>Sets the adjustment level for the
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||
Out-Of-Memory killer for executed processes. Takes an integer
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||
between -1000 (to disable OOM killing for this process) and
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||
1000 (to make killing of this process under memory pressure
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very likely). See <ulink
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url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
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for details.</para></listitem>
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</varlistentry>
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||
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||
<varlistentry>
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||
<term><varname>IOSchedulingClass=</varname></term>
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||
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||
<listitem><para>Sets the I/O scheduling class for executed
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processes. Takes an integer between 0 and 3 or one of the
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||
strings <option>none</option>, <option>realtime</option>,
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<option>best-effort</option> or <option>idle</option>. See
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<citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for details.</para></listitem>
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</varlistentry>
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||
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<varlistentry>
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||
<term><varname>IOSchedulingPriority=</varname></term>
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||
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<listitem><para>Sets the I/O scheduling priority for executed
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||
processes. Takes an integer between 0 (highest priority) and 7
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||
(lowest priority). The available priorities depend on the
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selected I/O scheduling class (see above). See
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||
<citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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||
for details.</para></listitem>
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||
</varlistentry>
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<varlistentry>
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<term><varname>CPUSchedulingPolicy=</varname></term>
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||
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<listitem><para>Sets the CPU scheduling policy for executed
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||
processes. Takes one of
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<option>other</option>,
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<option>batch</option>,
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<option>idle</option>,
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<option>fifo</option> or
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<option>rr</option>. See
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<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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||
for details.</para></listitem>
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||
</varlistentry>
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||
|
||
<varlistentry>
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||
<term><varname>CPUSchedulingPriority=</varname></term>
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||
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||
<listitem><para>Sets the CPU scheduling priority for executed
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||
processes. The available priority range depends on the
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||
selected CPU scheduling policy (see above). For real-time
|
||
scheduling policies an integer between 1 (lowest priority) and
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||
99 (highest priority) can be used. See
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||
<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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||
for details. </para></listitem>
|
||
</varlistentry>
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||
|
||
<varlistentry>
|
||
<term><varname>CPUSchedulingResetOnFork=</varname></term>
|
||
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||
<listitem><para>Takes a boolean argument. If true, elevated
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||
CPU scheduling priorities and policies will be reset when the
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||
executed processes fork, and can hence not leak into child
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processes. See
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<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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||
for details. Defaults to false.</para></listitem>
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||
</varlistentry>
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||
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||
<varlistentry>
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||
<term><varname>CPUAffinity=</varname></term>
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||
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||
<listitem><para>Controls the CPU affinity of the executed
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||
processes. Takes a list of CPU indices or ranges separated by
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||
either whitespace or commas. CPU ranges are specified by the
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||
lower and upper CPU indices separated by a dash.
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||
This option may be specified more than once, in which case the
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||
specified CPU affinity masks are merged. If the empty string
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||
is assigned, the mask is reset, all assignments prior to this
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||
will have no effect. See
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||
<citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for details.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>UMask=</varname></term>
|
||
|
||
<listitem><para>Controls the file mode creation mask. Takes an
|
||
access mode in octal notation. See
|
||
<citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for details. Defaults to 0022.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>Environment=</varname></term>
|
||
|
||
<listitem><para>Sets environment variables for executed
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||
processes. Takes a space-separated list of variable
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||
assignments. This option may be specified more than once, in
|
||
which case all listed variables will be set. If the same
|
||
variable is set twice, the later setting will override the
|
||
earlier setting. If the empty string is assigned to this
|
||
option, the list of environment variables is reset, all prior
|
||
assignments have no effect. Variable expansion is not
|
||
performed inside the strings, however, specifier expansion is
|
||
possible. The $ character has no special meaning. If you need
|
||
to assign a value containing spaces to a variable, use double
|
||
quotes (") for the assignment.</para>
|
||
|
||
<para>Example:
|
||
<programlisting>Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</programlisting>
|
||
gives three variables <literal>VAR1</literal>,
|
||
<literal>VAR2</literal>, <literal>VAR3</literal>
|
||
with the values <literal>word1 word2</literal>,
|
||
<literal>word3</literal>, <literal>$word 5 6</literal>.
|
||
</para>
|
||
|
||
<para>
|
||
See
|
||
<citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
for details about environment variables.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>EnvironmentFile=</varname></term>
|
||
<listitem><para>Similar to <varname>Environment=</varname> but
|
||
reads the environment variables from a text file. The text
|
||
file should contain new-line-separated variable assignments.
|
||
Empty lines, lines without an <literal>=</literal> separator,
|
||
or lines starting with ; or # will be ignored,
|
||
which may be used for commenting. A line ending with a
|
||
backslash will be concatenated with the following one,
|
||
allowing multiline variable definitions. The parser strips
|
||
leading and trailing whitespace from the values of
|
||
assignments, unless you use double quotes (").</para>
|
||
|
||
<para>The argument passed should be an absolute filename or
|
||
wildcard expression, optionally prefixed with
|
||
<literal>-</literal>, which indicates that if the file does
|
||
not exist, it will not be read and no error or warning message
|
||
is logged. This option may be specified more than once in
|
||
which case all specified files are read. If the empty string
|
||
is assigned to this option, the list of file to read is reset,
|
||
all prior assignments have no effect.</para>
|
||
|
||
<para>The files listed with this directive will be read
|
||
shortly before the process is executed (more specifically,
|
||
after all processes from a previous unit state terminated.
|
||
This means you can generate these files in one unit state, and
|
||
read it with this option in the next).</para>
|
||
|
||
<para>Settings from these
|
||
files override settings made with
|
||
<varname>Environment=</varname>. If the same variable is set
|
||
twice from these files, the files will be read in the order
|
||
they are specified and the later setting will override the
|
||
earlier setting.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PassEnvironment=</varname></term>
|
||
|
||
<listitem><para>Pass environment variables from the systemd system
|
||
manager to executed processes. Takes a space-separated list of variable
|
||
names. This option may be specified more than once, in which case all
|
||
listed variables will be set. If the empty string is assigned to this
|
||
option, the list of environment variables is reset, all prior
|
||
assignments have no effect. Variables that are not set in the system
|
||
manager will not be passed and will be silently ignored.</para>
|
||
|
||
<para>Variables passed from this setting are overridden by those passed
|
||
from <varname>Environment=</varname> or
|
||
<varname>EnvironmentFile=</varname>.</para>
|
||
|
||
<para>Example:
|
||
<programlisting>PassEnvironment=VAR1 VAR2 VAR3</programlisting>
|
||
passes three variables <literal>VAR1</literal>,
|
||
<literal>VAR2</literal>, <literal>VAR3</literal>
|
||
with the values set for those variables in PID1.</para>
|
||
|
||
<para>
|
||
See
|
||
<citerefentry project='man-pages'><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
for details about environment variables.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>StandardInput=</varname></term>
|
||
<listitem><para>Controls where file descriptor 0 (STDIN) of
|
||
the executed processes is connected to. Takes one of
|
||
<option>null</option>,
|
||
<option>tty</option>,
|
||
<option>tty-force</option>,
|
||
<option>tty-fail</option> or
|
||
<option>socket</option>.</para>
|
||
|
||
<para>If <option>null</option> is selected, standard input
|
||
will be connected to <filename>/dev/null</filename>, i.e. all
|
||
read attempts by the process will result in immediate
|
||
EOF.</para>
|
||
|
||
<para>If <option>tty</option> is selected, standard input is
|
||
connected to a TTY (as configured by
|
||
<varname>TTYPath=</varname>, see below) and the executed
|
||
process becomes the controlling process of the terminal. If
|
||
the terminal is already being controlled by another process,
|
||
the executed process waits until the current controlling
|
||
process releases the terminal.</para>
|
||
|
||
<para><option>tty-force</option> is similar to
|
||
<option>tty</option>, but the executed process is forcefully
|
||
and immediately made the controlling process of the terminal,
|
||
potentially removing previous controlling processes from the
|
||
terminal.</para>
|
||
|
||
<para><option>tty-fail</option> is similar to
|
||
<option>tty</option> but if the terminal already has a
|
||
controlling process start-up of the executed process
|
||
fails.</para>
|
||
|
||
<para>The <option>socket</option> option is only valid in
|
||
socket-activated services, and only when the socket
|
||
configuration file (see
|
||
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for details) specifies a single socket only. If this option is
|
||
set, standard input will be connected to the socket the
|
||
service was activated from, which is primarily useful for
|
||
compatibility with daemons designed for use with the
|
||
traditional
|
||
<citerefentry project='freebsd'><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
daemon.</para>
|
||
|
||
<para>This setting defaults to
|
||
<option>null</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>StandardOutput=</varname></term>
|
||
<listitem><para>Controls where file descriptor 1 (STDOUT) of
|
||
the executed processes is connected to. Takes one of
|
||
<option>inherit</option>,
|
||
<option>null</option>,
|
||
<option>tty</option>,
|
||
<option>journal</option>,
|
||
<option>syslog</option>,
|
||
<option>kmsg</option>,
|
||
<option>journal+console</option>,
|
||
<option>syslog+console</option>,
|
||
<option>kmsg+console</option> or
|
||
<option>socket</option>.</para>
|
||
|
||
<para><option>inherit</option> duplicates the file descriptor
|
||
of standard input for standard output.</para>
|
||
|
||
<para><option>null</option> connects standard output to
|
||
<filename>/dev/null</filename>, i.e. everything written to it
|
||
will be lost.</para>
|
||
|
||
<para><option>tty</option> connects standard output to a tty
|
||
(as configured via <varname>TTYPath=</varname>, see below). If
|
||
the TTY is used for output only, the executed process will not
|
||
become the controlling process of the terminal, and will not
|
||
fail or wait for other processes to release the
|
||
terminal.</para>
|
||
|
||
<para><option>journal</option> connects standard output with
|
||
the journal which is accessible via
|
||
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
|
||
Note that everything that is written to syslog or kmsg (see
|
||
below) is implicitly stored in the journal as well, the
|
||
specific two options listed below are hence supersets of this
|
||
one.</para>
|
||
|
||
<para><option>syslog</option> connects standard output to the
|
||
<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
system syslog service, in addition to the journal. Note that
|
||
the journal daemon is usually configured to forward everything
|
||
it receives to syslog anyway, in which case this option is no
|
||
different from <option>journal</option>.</para>
|
||
|
||
<para><option>kmsg</option> connects standard output with the
|
||
kernel log buffer which is accessible via
|
||
<citerefentry project='man-pages'><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
in addition to the journal. The journal daemon might be
|
||
configured to send all logs to kmsg anyway, in which case this
|
||
option is no different from <option>journal</option>.</para>
|
||
|
||
<para><option>journal+console</option>,
|
||
<option>syslog+console</option> and
|
||
<option>kmsg+console</option> work in a similar way as the
|
||
three options above but copy the output to the system console
|
||
as well.</para>
|
||
|
||
<para><option>socket</option> connects standard output to a
|
||
socket acquired via socket activation. The semantics are
|
||
similar to the same option of
|
||
<varname>StandardInput=</varname>.</para>
|
||
|
||
<para>If the standard output (or error output, see below) of a unit is connected to the journal, syslog or the
|
||
kernel log buffer, the unit will implicitly gain a dependency of type <varname>After=</varname> on
|
||
<filename>systemd-journald.socket</filename> (also see the automatic dependencies section above).</para>
|
||
|
||
<para>This setting defaults to the value set with
|
||
<option>DefaultStandardOutput=</option> in
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which defaults to <option>journal</option>. Note that setting
|
||
this parameter might result in additional dependencies to be
|
||
added to the unit (see above).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>StandardError=</varname></term>
|
||
<listitem><para>Controls where file descriptor 2 (STDERR) of
|
||
the executed processes is connected to. The available options
|
||
are identical to those of <varname>StandardOutput=</varname>,
|
||
with one exception: if set to <option>inherit</option> the
|
||
file descriptor used for standard output is duplicated for
|
||
standard error. This setting defaults to the value set with
|
||
<option>DefaultStandardError=</option> in
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
which defaults to <option>inherit</option>. Note that setting
|
||
this parameter might result in additional dependencies to be
|
||
added to the unit (see above).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>TTYPath=</varname></term>
|
||
<listitem><para>Sets the terminal device node to use if
|
||
standard input, output, or error are connected to a TTY (see
|
||
above). Defaults to
|
||
<filename>/dev/console</filename>.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>TTYReset=</varname></term>
|
||
<listitem><para>Reset the terminal device specified with
|
||
<varname>TTYPath=</varname> before and after execution.
|
||
Defaults to <literal>no</literal>.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>TTYVHangup=</varname></term>
|
||
<listitem><para>Disconnect all clients which have opened the
|
||
terminal device specified with <varname>TTYPath=</varname>
|
||
before and after execution. Defaults to
|
||
<literal>no</literal>.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>TTYVTDisallocate=</varname></term>
|
||
<listitem><para>If the terminal device specified with
|
||
<varname>TTYPath=</varname> is a virtual console terminal, try
|
||
to deallocate the TTY before and after execution. This ensures
|
||
that the screen and scrollback buffer is cleared. Defaults to
|
||
<literal>no</literal>.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>SyslogIdentifier=</varname></term>
|
||
<listitem><para>Sets the process name to prefix log lines sent
|
||
to the logging system or the kernel log buffer with. If not
|
||
set, defaults to the process name of the executed process.
|
||
This option is only useful when
|
||
<varname>StandardOutput=</varname> or
|
||
<varname>StandardError=</varname> are set to
|
||
<option>syslog</option>, <option>journal</option> or
|
||
<option>kmsg</option> (or to the same settings in combination
|
||
with <option>+console</option>).</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>SyslogFacility=</varname></term>
|
||
<listitem><para>Sets the syslog facility to use when logging
|
||
to syslog. One of <option>kern</option>,
|
||
<option>user</option>, <option>mail</option>,
|
||
<option>daemon</option>, <option>auth</option>,
|
||
<option>syslog</option>, <option>lpr</option>,
|
||
<option>news</option>, <option>uucp</option>,
|
||
<option>cron</option>, <option>authpriv</option>,
|
||
<option>ftp</option>, <option>local0</option>,
|
||
<option>local1</option>, <option>local2</option>,
|
||
<option>local3</option>, <option>local4</option>,
|
||
<option>local5</option>, <option>local6</option> or
|
||
<option>local7</option>. See
|
||
<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
for details. This option is only useful when
|
||
<varname>StandardOutput=</varname> or
|
||
<varname>StandardError=</varname> are set to
|
||
<option>syslog</option>. Defaults to
|
||
<option>daemon</option>.</para></listitem>
|
||
</varlistentry>
|
||
<varlistentry>
|
||
<term><varname>SyslogLevel=</varname></term>
|
||
<listitem><para>The default syslog level to use when logging to
|
||
syslog or the kernel log buffer. One of
|
||
<option>emerg</option>,
|
||
<option>alert</option>,
|
||
<option>crit</option>,
|
||
<option>err</option>,
|
||
<option>warning</option>,
|
||
<option>notice</option>,
|
||
<option>info</option>,
|
||
<option>debug</option>. See
|
||
<citerefentry project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
for details. This option is only useful when
|
||
<varname>StandardOutput=</varname> or
|
||
<varname>StandardError=</varname> are set to
|
||
<option>syslog</option> or <option>kmsg</option>. Note that
|
||
individual lines output by the daemon might be prefixed with a
|
||
different log level which can be used to override the default
|
||
log level specified here. The interpretation of these prefixes
|
||
may be disabled with <varname>SyslogLevelPrefix=</varname>,
|
||
see below. For details, see
|
||
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
|
||
Defaults to
|
||
<option>info</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SyslogLevelPrefix=</varname></term>
|
||
<listitem><para>Takes a boolean argument. If true and
|
||
<varname>StandardOutput=</varname> or
|
||
<varname>StandardError=</varname> are set to
|
||
<option>syslog</option>, <option>kmsg</option> or
|
||
<option>journal</option>, log lines written by the executed
|
||
process that are prefixed with a log level will be passed on
|
||
to syslog with this log level set but the prefix removed. If
|
||
set to false, the interpretation of these prefixes is disabled
|
||
and the logged lines are passed on as-is. For details about
|
||
this prefixing see
|
||
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
Defaults to true.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>TimerSlackNSec=</varname></term>
|
||
<listitem><para>Sets the timer slack in nanoseconds for the
|
||
executed processes. The timer slack controls the accuracy of
|
||
wake-ups triggered by timers. See
|
||
<citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for more information. Note that in contrast to most other time
|
||
span definitions this parameter takes an integer value in
|
||
nano-seconds if no unit is specified. The usual time units are
|
||
understood too.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>LimitCPU=</varname></term>
|
||
<term><varname>LimitFSIZE=</varname></term>
|
||
<term><varname>LimitDATA=</varname></term>
|
||
<term><varname>LimitSTACK=</varname></term>
|
||
<term><varname>LimitCORE=</varname></term>
|
||
<term><varname>LimitRSS=</varname></term>
|
||
<term><varname>LimitNOFILE=</varname></term>
|
||
<term><varname>LimitAS=</varname></term>
|
||
<term><varname>LimitNPROC=</varname></term>
|
||
<term><varname>LimitMEMLOCK=</varname></term>
|
||
<term><varname>LimitLOCKS=</varname></term>
|
||
<term><varname>LimitSIGPENDING=</varname></term>
|
||
<term><varname>LimitMSGQUEUE=</varname></term>
|
||
<term><varname>LimitNICE=</varname></term>
|
||
<term><varname>LimitRTPRIO=</varname></term>
|
||
<term><varname>LimitRTTIME=</varname></term>
|
||
<listitem><para>Set soft and hard limits on various resources for executed processes. See
|
||
<citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry> for details on
|
||
the resource limit concept. Resource limits may be specified in two formats: either as single value to set a
|
||
specific soft and hard limit to the same value, or as colon-separated pair <option>soft:hard</option> to set
|
||
both limits individually (e.g. <literal>LimitAS=4G:16G</literal>). Use the string <varname>infinity</varname>
|
||
to configure no limit on a specific resource. The multiplicative suffixes K, M, G, T, P and E (to the base
|
||
1024) may be used for resource limits measured in bytes (e.g. LimitAS=16G). For the limits referring to time
|
||
values, the usual time units ms, s, min, h and so on may be used (see
|
||
<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
|
||
details). Note that if no time unit is specified for <varname>LimitCPU=</varname> the default unit of seconds
|
||
is implied, while for <varname>LimitRTTIME=</varname> the default unit of microseconds is implied. Also, note
|
||
that the effective granularity of the limits might influence their enforcement. For example, time limits
|
||
specified for <varname>LimitCPU=</varname> will be rounded up implicitly to multiples of 1s. For
|
||
<varname>LimitNICE=</varname> the value may be specified in two syntaxes: if prefixed with <literal>+</literal>
|
||
or <literal>-</literal>, the value is understood as regular Linux nice value in the range -20..19. If not
|
||
prefixed like this the value is understood as raw resource limit parameter in the range 0..40 (with 0 being
|
||
equivalent to 1).</para>
|
||
|
||
<para>Note that most process resource limits configured with
|
||
these options are per-process, and processes may fork in order
|
||
to acquire a new set of resources that are accounted
|
||
independently of the original process, and may thus escape
|
||
limits set. Also note that <varname>LimitRSS=</varname> is not
|
||
implemented on Linux, and setting it has no effect. Often it
|
||
is advisable to prefer the resource controls listed in
|
||
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
over these per-process limits, as they apply to services as a
|
||
whole, may be altered dynamically at runtime, and are
|
||
generally more expressive. For example,
|
||
<varname>MemoryLimit=</varname> is a more powerful (and
|
||
working) replacement for <varname>LimitRSS=</varname>.</para>
|
||
|
||
<table>
|
||
<title>Limit directives and their equivalent with ulimit</title>
|
||
|
||
<tgroup cols='3'>
|
||
<colspec colname='directive' />
|
||
<colspec colname='equivalent' />
|
||
<colspec colname='unit' />
|
||
<thead>
|
||
<row>
|
||
<entry>Directive</entry>
|
||
<entry>ulimit equivalent</entry>
|
||
<entry>Unit</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry>LimitCPU=</entry>
|
||
<entry>ulimit -t</entry>
|
||
<entry>Seconds</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitFSIZE=</entry>
|
||
<entry>ulimit -f</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitDATA=</entry>
|
||
<entry>ulimit -d</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitSTACK=</entry>
|
||
<entry>ulimit -s</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitCORE=</entry>
|
||
<entry>ulimit -c</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitRSS=</entry>
|
||
<entry>ulimit -m</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitNOFILE=</entry>
|
||
<entry>ulimit -n</entry>
|
||
<entry>Number of File Descriptors</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitAS=</entry>
|
||
<entry>ulimit -v</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitNPROC=</entry>
|
||
<entry>ulimit -u</entry>
|
||
<entry>Number of Processes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitMEMLOCK=</entry>
|
||
<entry>ulimit -l</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitLOCKS=</entry>
|
||
<entry>ulimit -x</entry>
|
||
<entry>Number of Locks</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitSIGPENDING=</entry>
|
||
<entry>ulimit -i</entry>
|
||
<entry>Number of Queued Signals</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitMSGQUEUE=</entry>
|
||
<entry>ulimit -q</entry>
|
||
<entry>Bytes</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitNICE=</entry>
|
||
<entry>ulimit -e</entry>
|
||
<entry>Nice Level</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitRTPRIO=</entry>
|
||
<entry>ulimit -r</entry>
|
||
<entry>Realtime Priority</entry>
|
||
</row>
|
||
<row>
|
||
<entry>LimitRTTIME=</entry>
|
||
<entry>No equivalent</entry>
|
||
<entry>Microseconds</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PAMName=</varname></term>
|
||
<listitem><para>Sets the PAM service name to set up a session
|
||
as. If set, the executed process will be registered as a PAM
|
||
session under the specified service name. This is only useful
|
||
in conjunction with the <varname>User=</varname> setting. If
|
||
not set, no PAM session will be opened for the executed
|
||
processes. See
|
||
<citerefentry project='man-pages'><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
for details.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>CapabilityBoundingSet=</varname></term>
|
||
|
||
<listitem><para>Controls which capabilities to include in the capability bounding set for the executed
|
||
process. See <citerefentry
|
||
project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
|
||
details. Takes a whitespace-separated list of capability names as read by <citerefentry
|
||
project='mankier'><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
e.g. <constant>CAP_SYS_ADMIN</constant>, <constant>CAP_DAC_OVERRIDE</constant>,
|
||
<constant>CAP_SYS_PTRACE</constant>. Capabilities listed will be included in the bounding set, all others are
|
||
removed. If the list of capabilities is prefixed with <literal>~</literal>, all but the listed capabilities
|
||
will be included, the effect of the assignment inverted. Note that this option also affects the respective
|
||
capabilities in the effective, permitted and inheritable capability sets. If this option is not used, the
|
||
capability bounding set is not modified on process execution, hence no limits on the capabilities of the
|
||
process are enforced. This option may appear more than once, in which case the bounding sets are merged. If the
|
||
empty string is assigned to this option, the bounding set is reset to the empty capability set, and all prior
|
||
settings have no effect. If set to <literal>~</literal> (without any further argument), the bounding set is
|
||
reset to the full set of available capabilities, also undoing any previous settings. This does not affect
|
||
commands prefixed with <literal>+</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>AmbientCapabilities=</varname></term>
|
||
|
||
<listitem><para>Controls which capabilities to include in the
|
||
ambient capability set for the executed process. Takes a
|
||
whitespace-separated list of capability names as read by
|
||
<citerefentry project='mankier'><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
|
||
e.g. <constant>CAP_SYS_ADMIN</constant>,
|
||
<constant>CAP_DAC_OVERRIDE</constant>,
|
||
<constant>CAP_SYS_PTRACE</constant>. This option may appear more than
|
||
once in which case the ambient capability sets are merged.
|
||
If the list of capabilities is prefixed with <literal>~</literal>, all
|
||
but the listed capabilities will be included, the effect of the
|
||
assignment inverted. If the empty string is
|
||
assigned to this option, the ambient capability set is reset to
|
||
the empty capability set, and all prior settings have no effect.
|
||
If set to <literal>~</literal> (without any further argument), the
|
||
ambient capability set is reset to the full set of available
|
||
capabilities, also undoing any previous settings. Note that adding
|
||
capabilities to ambient capability set adds them to the process's
|
||
inherited capability set.
|
||
</para><para>
|
||
Ambient capability sets are useful if you want to execute a process
|
||
as a non-privileged user but still want to give it some capabilities.
|
||
Note that in this case option <constant>keep-caps</constant> is
|
||
automatically added to <varname>SecureBits=</varname> to retain the
|
||
capabilities over the user change. <varname>AmbientCapabilities=</varname> does not affect
|
||
commands prefixed with <literal>+</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SecureBits=</varname></term>
|
||
<listitem><para>Controls the secure bits set for the executed
|
||
process. Takes a space-separated combination of options from
|
||
the following list:
|
||
<option>keep-caps</option>,
|
||
<option>keep-caps-locked</option>,
|
||
<option>no-setuid-fixup</option>,
|
||
<option>no-setuid-fixup-locked</option>,
|
||
<option>noroot</option>, and
|
||
<option>noroot-locked</option>.
|
||
This option may appear more than once, in which case the secure
|
||
bits are ORed. If the empty string is assigned to this option,
|
||
the bits are reset to 0. This does not affect commands prefixed with <literal>+</literal>.
|
||
See <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
||
for details.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ReadWritePaths=</varname></term>
|
||
<term><varname>ReadOnlyPaths=</varname></term>
|
||
<term><varname>InaccessiblePaths=</varname></term>
|
||
|
||
<listitem><para>Sets up a new file system namespace for
|
||
executed processes. These options may be used to limit access
|
||
a process might have to the main file system hierarchy. Each
|
||
setting takes a space-separated list of paths relative to
|
||
the host's root directory (i.e. the system running the service manager).
|
||
Note that if entries contain symlinks, they are resolved from the host's root directory as well.
|
||
Entries (files or directories) listed in
|
||
<varname>ReadWritePaths=</varname> are accessible from
|
||
within the namespace with the same access rights as from
|
||
outside. Entries listed in
|
||
<varname>ReadOnlyPaths=</varname> are accessible for
|
||
reading only, writing will be refused even if the usual file
|
||
access controls would permit this. Entries listed in
|
||
<varname>InaccessiblePaths=</varname> will be made
|
||
inaccessible for processes inside the namespace, and may not
|
||
countain any other mountpoints, including those specified by
|
||
<varname>ReadWritePaths=</varname> or
|
||
<varname>ReadOnlyPaths=</varname>.
|
||
Note that restricting access with these options does not extend
|
||
to submounts of a directory that are created later on.
|
||
Non-directory paths can be specified as well. These
|
||
options may be specified more than once, in which case all
|
||
paths listed will have limited access from within the
|
||
namespace. If the empty string is assigned to this option, the
|
||
specific list is reset, and all prior assignments have no
|
||
effect.</para>
|
||
<para>Paths in
|
||
<varname>ReadOnlyPaths=</varname>
|
||
and
|
||
<varname>InaccessiblePaths=</varname>
|
||
may be prefixed with
|
||
<literal>-</literal>, in which case
|
||
they will be ignored when they do not
|
||
exist. Note that using this
|
||
setting will disconnect propagation of
|
||
mounts from the service to the host
|
||
(propagation in the opposite direction
|
||
continues to work). This means that
|
||
this setting may not be used for
|
||
services which shall be able to
|
||
install mount points in the main mount
|
||
namespace.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PrivateTmp=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, sets up a new file system namespace for the executed
|
||
processes and mounts private <filename>/tmp</filename> and <filename>/var/tmp</filename> directories inside it
|
||
that is not shared by processes outside of the namespace. This is useful to secure access to temporary files of
|
||
the process, but makes sharing between processes via <filename>/tmp</filename> or <filename>/var/tmp</filename>
|
||
impossible. If this is enabled, all temporary files created by a service in these directories will be removed
|
||
after the service is stopped. Defaults to false. It is possible to run two or more units within the same
|
||
private <filename>/tmp</filename> and <filename>/var/tmp</filename> namespace by using the
|
||
<varname>JoinsNamespaceOf=</varname> directive, see
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
|
||
details. Note that using this setting will disconnect propagation of mounts from the service to the host
|
||
(propagation in the opposite direction continues to work). This means that this setting may not be used for
|
||
services which shall be able to install mount points in the main mount namespace. This setting is implied if
|
||
<varname>DynamicUser=</varname> is set.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PrivateDevices=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, sets up a
|
||
new /dev namespace for the executed processes and only adds
|
||
API pseudo devices such as <filename>/dev/null</filename>,
|
||
<filename>/dev/zero</filename> or
|
||
<filename>/dev/random</filename> (as well as the pseudo TTY
|
||
subsystem) to it, but no physical devices such as
|
||
<filename>/dev/sda</filename>. This is useful to securely turn
|
||
off physical device access by the executed process. Defaults
|
||
to false. Enabling this option will also remove
|
||
<constant>CAP_MKNOD</constant> from the capability bounding
|
||
set for the unit (see above), and set
|
||
<varname>DevicePolicy=closed</varname> (see
|
||
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for details). Note that using this setting will disconnect
|
||
propagation of mounts from the service to the host
|
||
(propagation in the opposite direction continues to work).
|
||
This means that this setting may not be used for services
|
||
which shall be able to install mount points in the main mount
|
||
namespace. The /dev namespace will be mounted read-only and 'noexec'.
|
||
The latter may break old programs which try to set up executable
|
||
memory by using <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
of <filename>/dev/zero</filename> instead of using <constant>MAP_ANON</constant>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PrivateNetwork=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, sets up a
|
||
new network namespace for the executed processes and
|
||
configures only the loopback network device
|
||
<literal>lo</literal> inside it. No other network devices will
|
||
be available to the executed process. This is useful to
|
||
securely turn off network access by the executed process.
|
||
Defaults to false. It is possible to run two or more units
|
||
within the same private network namespace by using the
|
||
<varname>JoinsNamespaceOf=</varname> directive, see
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
for details. Note that this option will disconnect all socket
|
||
families from the host, this includes AF_NETLINK and AF_UNIX.
|
||
The latter has the effect that AF_UNIX sockets in the abstract
|
||
socket namespace will become unavailable to the processes
|
||
(however, those located in the file system will continue to be
|
||
accessible).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>PrivateUsers=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, sets up a new user namespace for the executed processes and
|
||
configures a minimal user and group mapping, that maps the <literal>root</literal> user and group as well as
|
||
the unit's own user and group to themselves and everything else to the <literal>nobody</literal> user and
|
||
group. This is useful to securely detach the user and group databases used by the unit from the rest of the
|
||
system, and thus to create an effective sandbox environment. All files, directories, processes, IPC objects and
|
||
other resources owned by users/groups not equalling <literal>root</literal> or the unit's own will stay visible
|
||
from within the unit but appear owned by the <literal>nobody</literal> user and group. If this mode is enabled,
|
||
all unit processes are run without privileges in the host user namespace (regardless if the unit's own
|
||
user/group is <literal>root</literal> or not). Specifically this means that the process will have zero process
|
||
capabilities on the host's user namespace, but full capabilities within the service's user namespace. Settings
|
||
such as <varname>CapabilityBoundingSet=</varname> will affect only the latter, and there's no way to acquire
|
||
additional capabilities in the host's user namespace. Defaults to off.</para>
|
||
|
||
<para>This setting is particularly useful in conjunction with <varname>RootDirectory=</varname>, as the need to
|
||
synchronize the user and group databases in the root directory and on the host is reduced, as the only users
|
||
and groups who need to be matched are <literal>root</literal>, <literal>nobody</literal> and the unit's own
|
||
user and group.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ProtectSystem=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or
|
||
<literal>full</literal>. If true, mounts the
|
||
<filename>/usr</filename> and <filename>/boot</filename>
|
||
directories read-only for processes invoked by this unit. If
|
||
set to <literal>full</literal>, the <filename>/etc</filename>
|
||
directory is mounted read-only, too. This setting ensures that
|
||
any modification of the vendor-supplied operating system (and
|
||
optionally its configuration) is prohibited for the service.
|
||
It is recommended to enable this setting for all long-running
|
||
services, unless they are involved with system updates or need
|
||
to modify the operating system in other ways. Note however
|
||
that processes retaining the CAP_SYS_ADMIN capability can undo
|
||
the effect of this setting. This setting is hence particularly
|
||
useful for daemons which have this capability removed, for
|
||
example with <varname>CapabilityBoundingSet=</varname>.
|
||
Defaults to off.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>ProtectHome=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or
|
||
<literal>read-only</literal>. If true, the directories
|
||
<filename>/home</filename>, <filename>/root</filename> and
|
||
<filename>/run/user</filename>
|
||
are made inaccessible and empty for processes invoked by this
|
||
unit. If set to <literal>read-only</literal>, the three
|
||
directories are made read-only instead. It is recommended to
|
||
enable this setting for all long-running services (in
|
||
particular network-facing ones), to ensure they cannot get
|
||
access to private user data, unless the services actually
|
||
require access to the user's private data. Note however that
|
||
processes retaining the CAP_SYS_ADMIN capability can undo the
|
||
effect of this setting. This setting is hence particularly
|
||
useful for daemons which have this capability removed, for
|
||
example with <varname>CapabilityBoundingSet=</varname>.
|
||
Defaults to off.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>MountFlags=</varname></term>
|
||
|
||
<listitem><para>Takes a mount propagation flag:
|
||
<option>shared</option>, <option>slave</option> or
|
||
<option>private</option>, which control whether mounts in the
|
||
file system namespace set up for this unit's processes will
|
||
receive or propagate mounts or unmounts. See
|
||
<citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
for details. Defaults to <option>shared</option>. Use
|
||
<option>shared</option> to ensure that mounts and unmounts are
|
||
propagated from the host to the container and vice versa. Use
|
||
<option>slave</option> to run processes so that none of their
|
||
mounts and unmounts will propagate to the host. Use
|
||
<option>private</option> to also ensure that no mounts and
|
||
unmounts from the host will propagate into the unit processes'
|
||
namespace. Note that <option>slave</option> means that file
|
||
systems mounted on the host might stay mounted continuously in
|
||
the unit's namespace, and thus keep the device busy. Note that
|
||
the file system namespace related options
|
||
(<varname>PrivateTmp=</varname>,
|
||
<varname>PrivateDevices=</varname>,
|
||
<varname>ProtectSystem=</varname>,
|
||
<varname>ProtectHome=</varname>,
|
||
<varname>ReadOnlyPaths=</varname>,
|
||
<varname>InaccessiblePaths=</varname> and
|
||
<varname>ReadWritePaths=</varname>) require that mount
|
||
and unmount propagation from the unit's file system namespace
|
||
is disabled, and hence downgrade <option>shared</option> to
|
||
<option>slave</option>. </para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>UtmpIdentifier=</varname></term>
|
||
|
||
<listitem><para>Takes a four character identifier string for
|
||
an <citerefentry
|
||
project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and wtmp entry for this service. This should only be
|
||
set for services such as <command>getty</command>
|
||
implementations (such as <citerefentry
|
||
project='die-net'><refentrytitle>agetty</refentrytitle><manvolnum>8</manvolnum></citerefentry>)
|
||
where utmp/wtmp entries must be created and cleared before and
|
||
after execution, or for services that shall be executed as if
|
||
they were run by a <command>getty</command> process (see
|
||
below). If the configured string is longer than four
|
||
characters, it is truncated and the terminal four characters
|
||
are used. This setting interprets %I style string
|
||
replacements. This setting is unset by default, i.e. no
|
||
utmp/wtmp entries are created or cleaned up for this
|
||
service.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>UtmpMode=</varname></term>
|
||
|
||
<listitem><para>Takes one of <literal>init</literal>,
|
||
<literal>login</literal> or <literal>user</literal>. If
|
||
<varname>UtmpIdentifier=</varname> is set, controls which
|
||
type of <citerefentry
|
||
project='man-pages'><refentrytitle>utmp</refentrytitle><manvolnum>5</manvolnum></citerefentry>/wtmp
|
||
entries for this service are generated. This setting has no
|
||
effect unless <varname>UtmpIdentifier=</varname> is set
|
||
too. If <literal>init</literal> is set, only an
|
||
<constant>INIT_PROCESS</constant> entry is generated and the
|
||
invoked process must implement a
|
||
<command>getty</command>-compatible utmp/wtmp logic. If
|
||
<literal>login</literal> is set, first an
|
||
<constant>INIT_PROCESS</constant> entry, followed by a
|
||
<constant>LOGIN_PROCESS</constant> entry is generated. In
|
||
this case, the invoked process must implement a <citerefentry
|
||
project='die-net'><refentrytitle>login</refentrytitle><manvolnum>1</manvolnum></citerefentry>-compatible
|
||
utmp/wtmp logic. If <literal>user</literal> is set, first an
|
||
<constant>INIT_PROCESS</constant> entry, then a
|
||
<constant>LOGIN_PROCESS</constant> entry and finally a
|
||
<constant>USER_PROCESS</constant> entry is generated. In this
|
||
case, the invoked process may be any process that is suitable
|
||
to be run as session leader. Defaults to
|
||
<literal>init</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SELinuxContext=</varname></term>
|
||
|
||
<listitem><para>Set the SELinux security context of the
|
||
executed process. If set, this will override the automated
|
||
domain transition. However, the policy still needs to
|
||
authorize the transition. This directive is ignored if SELinux
|
||
is disabled. If prefixed by <literal>-</literal>, all errors
|
||
will be ignored. This does not affect commands prefixed with <literal>+</literal>.
|
||
See <citerefentry project='die-net'><refentrytitle>setexeccon</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
for details.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>AppArmorProfile=</varname></term>
|
||
|
||
<listitem><para>Takes a profile name as argument. The process
|
||
executed by the unit will switch to this profile when started.
|
||
Profiles must already be loaded in the kernel, or the unit
|
||
will fail. This result in a non operation if AppArmor is not
|
||
enabled. If prefixed by <literal>-</literal>, all errors will
|
||
be ignored. This does not affect commands prefixed with <literal>+</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SmackProcessLabel=</varname></term>
|
||
|
||
<listitem><para>Takes a <option>SMACK64</option> security
|
||
label as argument. The process executed by the unit will be
|
||
started under this label and SMACK will decide whether the
|
||
process is allowed to run or not, based on it. The process
|
||
will continue to run under the label specified here unless the
|
||
executable has its own <option>SMACK64EXEC</option> label, in
|
||
which case the process will transition to run under that
|
||
label. When not specified, the label that systemd is running
|
||
under is used. This directive is ignored if SMACK is
|
||
disabled.</para>
|
||
|
||
<para>The value may be prefixed by <literal>-</literal>, in
|
||
which case all errors will be ignored. An empty value may be
|
||
specified to unset previous assignments. This does not affect
|
||
commands prefixed with <literal>+</literal>.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>IgnoreSIGPIPE=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, causes
|
||
<constant>SIGPIPE</constant> to be ignored in the executed
|
||
process. Defaults to true because <constant>SIGPIPE</constant>
|
||
generally is useful only in shell pipelines.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>NoNewPrivileges=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If true, ensures
|
||
that the service process and all its children can never gain
|
||
new privileges. This option is more powerful than the
|
||
respective secure bits flags (see above), as it also prohibits
|
||
UID changes of any kind. This is the simplest, most effective
|
||
way to ensure that a process and its children can never
|
||
elevate privileges again.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SystemCallFilter=</varname></term>
|
||
|
||
<listitem><para>Takes a space-separated list of system call
|
||
names. If this setting is used, all system calls executed by
|
||
the unit processes except for the listed ones will result in
|
||
immediate process termination with the
|
||
<constant>SIGSYS</constant> signal (whitelisting). If the
|
||
first character of the list is <literal>~</literal>, the
|
||
effect is inverted: only the listed system calls will result
|
||
in immediate process termination (blacklisting). If running in
|
||
user mode, or in system mode, but without the
|
||
<constant>CAP_SYS_ADMIN</constant> capability (e.g. setting
|
||
<varname>User=nobody</varname>),
|
||
<varname>NoNewPrivileges=yes</varname> is implied. This
|
||
feature makes use of the Secure Computing Mode 2 interfaces of
|
||
the kernel ('seccomp filtering') and is useful for enforcing a
|
||
minimal sandboxing environment. Note that the
|
||
<function>execve</function>,
|
||
<function>rt_sigreturn</function>,
|
||
<function>sigreturn</function>,
|
||
<function>exit_group</function>, <function>exit</function>
|
||
system calls are implicitly whitelisted and do not need to be
|
||
listed explicitly. This option may be specified more than once,
|
||
in which case the filter masks are merged. If the empty string
|
||
is assigned, the filter is reset, all prior assignments will
|
||
have no effect. This does not affect commands prefixed with <literal>+</literal>.</para>
|
||
|
||
<para>If you specify both types of this option (i.e.
|
||
whitelisting and blacklisting), the first encountered will
|
||
take precedence and will dictate the default action
|
||
(termination or approval of a system call). Then the next
|
||
occurrences of this option will add or delete the listed
|
||
system calls from the set of the filtered system calls,
|
||
depending of its type and the default action. (For example, if
|
||
you have started with a whitelisting of
|
||
<function>read</function> and <function>write</function>, and
|
||
right after it add a blacklisting of
|
||
<function>write</function>, then <function>write</function>
|
||
will be removed from the set.)</para>
|
||
|
||
<para>As the number of possible system
|
||
calls is large, predefined sets of system calls are provided.
|
||
A set starts with <literal>@</literal> character, followed by
|
||
name of the set.
|
||
|
||
<table>
|
||
<title>Currently predefined system call sets</title>
|
||
|
||
<tgroup cols='2'>
|
||
<colspec colname='set' />
|
||
<colspec colname='description' />
|
||
<thead>
|
||
<row>
|
||
<entry>Set</entry>
|
||
<entry>Description</entry>
|
||
</row>
|
||
</thead>
|
||
<tbody>
|
||
<row>
|
||
<entry>@clock</entry>
|
||
<entry>System calls for changing the system clock (<citerefentry project='man-pages'><refentrytitle>adjtimex</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>settimeofday</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@cpu-emulation</entry>
|
||
<entry>System calls for CPU emulation functionality (<citerefentry project='man-pages'><refentrytitle>vm86</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@debug</entry>
|
||
<entry>Debugging, performance monitoring and tracing functionality (<citerefentry project='man-pages'><refentrytitle>ptrace</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>perf_event_open</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@io-event</entry>
|
||
<entry>Event loop system calls (<citerefentry project='man-pages'><refentrytitle>poll</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>select</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>epoll</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>eventfd</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@ipc</entry>
|
||
<entry>SysV IPC, POSIX Message Queues or other IPC (<citerefentry project='man-pages'><refentrytitle>mq_overview</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>svipc</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@keyring</entry>
|
||
<entry>Kernel keyring access (<citerefentry project='man-pages'><refentrytitle>keyctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@module</entry>
|
||
<entry>Kernel module control (<citerefentry project='man-pages'><refentrytitle>init_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>delete_module</refentrytitle><manvolnum>2</manvolnum></citerefentry> and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@mount</entry>
|
||
<entry>File system mounting and unmounting (<citerefentry project='man-pages'><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>, and related calls)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@network-io</entry>
|
||
<entry>Socket I/O (including local AF_UNIX): <citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>7</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>unix</refentrytitle><manvolnum>7</manvolnum></citerefentry></entry>
|
||
</row>
|
||
<row>
|
||
<entry>@obsolete</entry>
|
||
<entry>Unusual, obsolete or unimplemented (<citerefentry project='man-pages'><refentrytitle>create_module</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>gtty</refentrytitle><manvolnum>2</manvolnum></citerefentry>, …)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@privileged</entry>
|
||
<entry>All system calls which need super-user capabilities (<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>)</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@process</entry>
|
||
<entry>Process control, execution, namespaces (<citerefentry project='man-pages'><refentrytitle>execve</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>namespaces</refentrytitle><manvolnum>7</manvolnum></citerefentry>, …</entry>
|
||
</row>
|
||
<row>
|
||
<entry>@raw-io</entry>
|
||
<entry>Raw I/O port access (<citerefentry project='man-pages'><refentrytitle>ioperm</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>iopl</refentrytitle><manvolnum>2</manvolnum></citerefentry>, <function>pciconfig_read()</function>, …</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
|
||
Note, that as new system calls are added to the kernel, additional system calls might be added to the groups
|
||
above, so the contents of the sets may change between systemd versions.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SystemCallErrorNumber=</varname></term>
|
||
|
||
<listitem><para>Takes an <literal>errno</literal> error number
|
||
name to return when the system call filter configured with
|
||
<varname>SystemCallFilter=</varname> is triggered, instead of
|
||
terminating the process immediately. Takes an error name such
|
||
as <constant>EPERM</constant>, <constant>EACCES</constant> or
|
||
<constant>EUCLEAN</constant>. When this setting is not used,
|
||
or when the empty string is assigned, the process will be
|
||
terminated immediately when the filter is
|
||
triggered.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>SystemCallArchitectures=</varname></term>
|
||
|
||
<listitem><para>Takes a space-separated list of architecture
|
||
identifiers to include in the system call filter. The known
|
||
architecture identifiers are <constant>x86</constant>,
|
||
<constant>x86-64</constant>, <constant>x32</constant>,
|
||
<constant>arm</constant> as well as the special identifier
|
||
<constant>native</constant>. Only system calls of the
|
||
specified architectures will be permitted to processes of this
|
||
unit. This is an effective way to disable compatibility with
|
||
non-native architectures for processes, for example to
|
||
prohibit execution of 32-bit x86 binaries on 64-bit x86-64
|
||
systems. The special <constant>native</constant> identifier
|
||
implicitly maps to the native architecture of the system (or
|
||
more strictly: to the architecture the system manager is
|
||
compiled for). If running in user mode, or in system mode,
|
||
but without the <constant>CAP_SYS_ADMIN</constant>
|
||
capability (e.g. setting <varname>User=nobody</varname>),
|
||
<varname>NoNewPrivileges=yes</varname> is implied. Note
|
||
that setting this option to a non-empty list implies that
|
||
<constant>native</constant> is included too. By default, this
|
||
option is set to the empty list, i.e. no architecture system
|
||
call filtering is applied.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RestrictAddressFamilies=</varname></term>
|
||
|
||
<listitem><para>Restricts the set of socket address families
|
||
accessible to the processes of this unit. Takes a
|
||
space-separated list of address family names to whitelist,
|
||
such as
|
||
<constant>AF_UNIX</constant>,
|
||
<constant>AF_INET</constant> or
|
||
<constant>AF_INET6</constant>. When
|
||
prefixed with <constant>~</constant> the listed address
|
||
families will be applied as blacklist, otherwise as whitelist.
|
||
Note that this restricts access to the
|
||
<citerefentry project='man-pages'><refentrytitle>socket</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
system call only. Sockets passed into the process by other
|
||
means (for example, by using socket activation with socket
|
||
units, see
|
||
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
|
||
are unaffected. Also, sockets created with
|
||
<function>socketpair()</function> (which creates connected
|
||
AF_UNIX sockets only) are unaffected. Note that this option
|
||
has no effect on 32-bit x86 and is ignored (but works
|
||
correctly on x86-64). If running in user mode, or in system
|
||
mode, but without the <constant>CAP_SYS_ADMIN</constant>
|
||
capability (e.g. setting <varname>User=nobody</varname>),
|
||
<varname>NoNewPrivileges=yes</varname> is implied. By
|
||
default, no restriction applies, all address families are
|
||
accessible to processes. If assigned the empty string, any
|
||
previous list changes are undone.</para>
|
||
|
||
<para>Use this option to limit exposure of processes to remote
|
||
systems, in particular via exotic network protocols. Note that
|
||
in most cases, the local <constant>AF_UNIX</constant> address
|
||
family should be included in the configured whitelist as it is
|
||
frequently used for local communication, including for
|
||
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
logging. This does not affect commands prefixed with <literal>+</literal>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>Personality=</varname></term>
|
||
|
||
<listitem><para>Controls which kernel architecture <citerefentry
|
||
project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry> shall report,
|
||
when invoked by unit processes. Takes one of the architecture identifiers <constant>x86</constant>,
|
||
<constant>x86-64</constant>, <constant>ppc</constant>, <constant>ppc-le</constant>, <constant>ppc64</constant>,
|
||
<constant>ppc64-le</constant>, <constant>s390</constant> or <constant>s390x</constant>. Which personality
|
||
architectures are supported depends on the system architecture. Usually the 64bit versions of the various
|
||
system architectures support their immediate 32bit personality architecture counterpart, but no others. For
|
||
example, <constant>x86-64</constant> systems support the <constant>x86-64</constant> and
|
||
<constant>x86</constant> personalities but no others. The personality feature is useful when running 32-bit
|
||
services on a 64-bit host system. If not specified, the personality is left unmodified and thus reflects the
|
||
personality of the host system's kernel.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RuntimeDirectory=</varname></term>
|
||
<term><varname>RuntimeDirectoryMode=</varname></term>
|
||
|
||
<listitem><para>Takes a list of directory names. If set, one
|
||
or more directories by the specified names will be created
|
||
below <filename>/run</filename> (for system services) or below
|
||
<varname>$XDG_RUNTIME_DIR</varname> (for user services) when
|
||
the unit is started, and removed when the unit is stopped. The
|
||
directories will have the access mode specified in
|
||
<varname>RuntimeDirectoryMode=</varname>, and will be owned by
|
||
the user and group specified in <varname>User=</varname> and
|
||
<varname>Group=</varname>. Use this to manage one or more
|
||
runtime directories of the unit and bind their lifetime to the
|
||
daemon runtime. The specified directory names must be
|
||
relative, and may not include a <literal>/</literal>, i.e.
|
||
must refer to simple directories to create or remove. This is
|
||
particularly useful for unprivileged daemons that cannot
|
||
create runtime directories in <filename>/run</filename> due to
|
||
lack of privileges, and to make sure the runtime directory is
|
||
cleaned up automatically after use. For runtime directories
|
||
that require more complex or different configuration or
|
||
lifetime guarantees, please consider using
|
||
<citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>MemoryDenyWriteExecute=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If set, attempts to create memory mappings that are writable and
|
||
executable at the same time, or to change existing memory mappings to become executable are prohibited.
|
||
Specifically, a system call filter is added that rejects
|
||
<citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
system calls with both <constant>PROT_EXEC</constant> and <constant>PROT_WRITE</constant> set
|
||
and <citerefentry><refentrytitle>mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
||
system calls with <constant>PROT_EXEC</constant> set. Note that this option is incompatible with programs
|
||
that generate program code dynamically at runtime, such as JIT execution engines, or programs compiled making
|
||
use of the code "trampoline" feature of various C compilers. This option improves service security, as it makes
|
||
harder for software exploits to change running code dynamically.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>RestrictRealtime=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If set, any attempts to enable realtime scheduling in a process of
|
||
the unit are refused. This restricts access to realtime task scheduling policies such as
|
||
<constant>SCHED_FIFO</constant>, <constant>SCHED_RR</constant> or <constant>SCHED_DEADLINE</constant>. See
|
||
<citerefentry project='man-pages'><refentrytitle>sched</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details about
|
||
these scheduling policies. Realtime scheduling policies may be used to monopolize CPU time for longer periods
|
||
of time, and may hence be used to lock up or otherwise trigger Denial-of-Service situations on the system. It
|
||
is hence recommended to restrict access to realtime scheduling to the few programs that actually require
|
||
them. Defaults to off.</para></listitem>
|
||
</varlistentry>
|
||
|
||
</variablelist>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Environment variables in spawned processes</title>
|
||
|
||
<para>Processes started by the system are executed in a clean
|
||
environment in which select variables listed below are set. System
|
||
processes started by systemd do not inherit variables from PID 1,
|
||
but processes started by user systemd instances inherit all
|
||
environment variables from the user systemd instance.
|
||
</para>
|
||
|
||
<variablelist class='environment-variables'>
|
||
<varlistentry>
|
||
<term><varname>$PATH</varname></term>
|
||
|
||
<listitem><para>Colon-separated list of directories to use
|
||
when launching executables. Systemd uses a fixed value of
|
||
<filename>/usr/local/sbin</filename>:<filename>/usr/local/bin</filename>:<filename>/usr/sbin</filename>:<filename>/usr/bin</filename>:<filename>/sbin</filename>:<filename>/bin</filename>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$LANG</varname></term>
|
||
|
||
<listitem><para>Locale. Can be set in
|
||
<citerefentry project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
or on the kernel command line (see
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$USER</varname></term>
|
||
<term><varname>$LOGNAME</varname></term>
|
||
<term><varname>$HOME</varname></term>
|
||
<term><varname>$SHELL</varname></term>
|
||
|
||
<listitem><para>User name (twice), home directory, and the
|
||
login shell. The variables are set for the units that have
|
||
<varname>User=</varname> set, which includes user
|
||
<command>systemd</command> instances. See
|
||
<citerefentry project='die-net'><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$XDG_RUNTIME_DIR</varname></term>
|
||
|
||
<listitem><para>The directory for volatile state. Set for the
|
||
user <command>systemd</command> instance, and also in user
|
||
sessions. See
|
||
<citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$XDG_SESSION_ID</varname></term>
|
||
<term><varname>$XDG_SEAT</varname></term>
|
||
<term><varname>$XDG_VTNR</varname></term>
|
||
|
||
<listitem><para>The identifier of the session, the seat name,
|
||
and virtual terminal of the session. Set by
|
||
<citerefentry><refentrytitle>pam_systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
|
||
for login sessions. <varname>$XDG_SEAT</varname> and
|
||
<varname>$XDG_VTNR</varname> will only be set when attached to
|
||
a seat and a tty.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$MAINPID</varname></term>
|
||
|
||
<listitem><para>The PID of the units main process if it is
|
||
known. This is only set for control processes as invoked by
|
||
<varname>ExecReload=</varname> and similar. </para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$MANAGERPID</varname></term>
|
||
|
||
<listitem><para>The PID of the user <command>systemd</command>
|
||
instance, set for processes spawned by it. </para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$LISTEN_FDS</varname></term>
|
||
<term><varname>$LISTEN_PID</varname></term>
|
||
<term><varname>$LISTEN_FDNAMES</varname></term>
|
||
|
||
<listitem><para>Information about file descriptors passed to a
|
||
service for socket activation. See
|
||
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$NOTIFY_SOCKET</varname></term>
|
||
|
||
<listitem><para>The socket
|
||
<function>sd_notify()</function> talks to. See
|
||
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$WATCHDOG_PID</varname></term>
|
||
<term><varname>$WATCHDOG_USEC</varname></term>
|
||
|
||
<listitem><para>Information about watchdog keep-alive notifications. See
|
||
<citerefentry><refentrytitle>sd_watchdog_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$TERM</varname></term>
|
||
|
||
<listitem><para>Terminal type, set only for units connected to
|
||
a terminal (<varname>StandardInput=tty</varname>,
|
||
<varname>StandardOutput=tty</varname>, or
|
||
<varname>StandardError=tty</varname>). See
|
||
<citerefentry project='man-pages'><refentrytitle>termcap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$JOURNAL_STREAM</varname></term>
|
||
|
||
<listitem><para>If the standard output or standard error output of the executed processes are connected to the
|
||
journal (for example, by setting <varname>StandardError=journal</varname>) <varname>$JOURNAL_STREAM</varname>
|
||
contains the device and inode numbers of the connection file descriptor, formatted in decimal, separated by a
|
||
colon (<literal>:</literal>). This permits invoked processes to safely detect whether their standard output or
|
||
standard error output are connected to the journal. The device and inode numbers of the file descriptors should
|
||
be compared with the values set in the environment variable to determine whether the process output is still
|
||
connected to the journal. Note that it is generally not sufficient to only check whether
|
||
<varname>$JOURNAL_STREAM</varname> is set at all as services might invoke external processes replacing their
|
||
standard output or standard error output, without unsetting the environment variable.</para>
|
||
|
||
<para>This environment variable is primarily useful to allow services to optionally upgrade their used log
|
||
protocol to the native journal protocol (using
|
||
<citerefentry><refentrytitle>sd_journal_print</refentrytitle><manvolnum>3</manvolnum></citerefentry> and other
|
||
functions) if their standard output or standard error output is connected to the journal anyway, thus enabling
|
||
delivery of structured metadata along with logged messages.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SERVICE_RESULT</varname></term>
|
||
|
||
<listitem><para>Only defined for the service unit type, this environment variable is passed to all
|
||
<varname>ExecStop=</varname> and <varname>ExecStopPost=</varname> processes, and encodes the service
|
||
"result". Currently, the following values are defined: <literal>timeout</literal> (in case of an operation
|
||
timeout), <literal>exit-code</literal> (if a service process exited with a non-zero exit code; see
|
||
<varname>$EXIT_STATUS</varname> below for the actual exit status returned), <literal>signal</literal> (if a
|
||
service process was terminated abnormally by a signal; see <varname>$EXIT_STATUS</varname> below for the actual
|
||
signal used for the termination), <literal>core-dump</literal> (if a service process terminated abnormally and
|
||
dumped core), <literal>watchdog</literal> (if the watchdog keep-alive ping was enabled for the service but it
|
||
missed the deadline), or <literal>resources</literal> (a catch-all condition in case a system operation
|
||
failed).</para>
|
||
|
||
<para>This environment variable is useful to monitor failure or successful termination of a service. Even
|
||
though this variable is available in both <varname>ExecStop=</varname> and <varname>ExecStopPost=</varname>, it
|
||
is usually a better choice to place monitoring tools in the latter, as the former is only invoked for services
|
||
that managed to start up correctly, and the latter covers both services that failed during their start-up and
|
||
those which failed during their runtime.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$EXIT_CODE</varname></term>
|
||
<term><varname>$EXIT_STATUS</varname></term>
|
||
|
||
<listitem><para>Only defined for the service unit type, these environment variables are passed to all
|
||
<varname>ExecStop=</varname>, <varname>ExecStopPost=</varname> processes and contain exit status/code
|
||
information of the main process of the service. For the precise definition of the exit code and status, see
|
||
<citerefentry><refentrytitle>wait</refentrytitle><manvolnum>2</manvolnum></citerefentry>. <varname>$EXIT_CODE</varname>
|
||
is one of <literal>exited</literal>, <literal>killed</literal>,
|
||
<literal>dumped</literal>. <varname>$EXIT_STATUS</varname> contains the numeric exit code formatted as string
|
||
if <varname>$EXIT_CODE</varname> is <literal>exited</literal>, and the signal name in all other cases. Note
|
||
that these environment variables are only set if the service manager succeeded to start and identify the main
|
||
process of the service.</para>
|
||
|
||
<table>
|
||
<title>Summary of possible service result variable values</title>
|
||
<tgroup cols='3'>
|
||
<colspec colname='result' />
|
||
<colspec colname='status' />
|
||
<colspec colname='code' />
|
||
<thead>
|
||
<row>
|
||
<entry><varname>$SERVICE_RESULT</varname></entry>
|
||
<entry><varname>$EXIT_STATUS</varname></entry>
|
||
<entry><varname>$EXIT_CODE</varname></entry>
|
||
</row>
|
||
</thead>
|
||
|
||
<tbody>
|
||
<row>
|
||
<entry morerows="1" valign="top"><literal>timeout</literal></entry>
|
||
<entry valign="top"><literal>killed</literal></entry>
|
||
<entry><literal>TERM</literal><sbr/><literal>KILL</literal></entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry valign="top"><literal>exited</literal></entry>
|
||
<entry><literal>0</literal><sbr/><literal>1</literal><sbr/><literal>2</literal><sbr/><literal
|
||
>3</literal><sbr/>…<sbr/><literal>255</literal></entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry valign="top"><literal>exit-code</literal></entry>
|
||
<entry valign="top"><literal>exited</literal></entry>
|
||
<entry><literal>0</literal><sbr/><literal>1</literal><sbr/><literal>2</literal><sbr/><literal
|
||
>3</literal><sbr/>…<sbr/><literal>255</literal></entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry valign="top"><literal>signal</literal></entry>
|
||
<entry valign="top"><literal>killed</literal></entry>
|
||
<entry><literal>HUP</literal><sbr/><literal>INT</literal><sbr/><literal>KILL</literal><sbr/>…</entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry valign="top"><literal>core-dump</literal></entry>
|
||
<entry valign="top"><literal>dumped</literal></entry>
|
||
<entry><literal>ABRT</literal><sbr/><literal>SEGV</literal><sbr/><literal>QUIT</literal><sbr/>…</entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry morerows="2" valign="top"><literal>watchdog</literal></entry>
|
||
<entry><literal>dumped</literal></entry>
|
||
<entry><literal>ABRT</literal></entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>killed</literal></entry>
|
||
<entry><literal>TERM</literal><sbr/><literal>KILL</literal></entry>
|
||
</row>
|
||
<row>
|
||
<entry><literal>exited</literal></entry>
|
||
<entry><literal>0</literal><sbr/><literal>1</literal><sbr/><literal>2</literal><sbr/><literal
|
||
>3</literal><sbr/>…<sbr/><literal>255</literal></entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry><literal>resources</literal></entry>
|
||
<entry>any of the above</entry>
|
||
<entry>any of the above</entry>
|
||
</row>
|
||
|
||
<row>
|
||
<entry namest="results" nameend="code">Note: the process may be also terminated by a signal not sent by systemd. In particular the process may send an arbitrary signal to itself in a handler for any of the non-maskable signals. Nevertheless, in the <literal>timeout</literal> and <literal>watchdog</literal> rows above only the signals that systemd sends have been included.</entry>
|
||
</row>
|
||
</tbody>
|
||
</tgroup>
|
||
</table>
|
||
|
||
</listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
|
||
<para>Additional variables may be configured by the following
|
||
means: for processes spawned in specific units, use the
|
||
<varname>Environment=</varname>, <varname>EnvironmentFile=</varname>
|
||
and <varname>PassEnvironment=</varname> options above; to specify
|
||
variables globally, use <varname>DefaultEnvironment=</varname>
|
||
(see
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
|
||
or the kernel option <varname>systemd.setenv=</varname> (see
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>).
|
||
Additional variables may also be set through PAM,
|
||
cf. <citerefentry project='man-pages'><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>See Also</title>
|
||
<para>
|
||
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry project='man-pages'><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
|
||
</para>
|
||
</refsect1>
|
||
|
||
|
||
</refentry>
|