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<refentry id="systemd.exec">
- <refentryinfo>
- <title>systemd.exec</title>
- <productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
- </refentryinfo>
-
- <refmeta>
- <refentrytitle>systemd.exec</refentrytitle>
- <manvolnum>5</manvolnum>
- </refmeta>
-
- <refnamediv>
- <refname>systemd.exec</refname>
- <refpurpose>systemd execution environment configuration</refpurpose>
- </refnamediv>
-
- <refsynopsisdiv>
- <para><filename>systemd.service</filename>,
- <filename>systemd.socket</filename>,
- <filename>systemd.mount</filename>,
- <filename>systemd.swap</filename></para>
- </refsynopsisdiv>
-
- <refsect1>
- <title>Description</title>
-
- <para>Unit configuration files for services, sockets,
- mount points and swap devices share a subset of
- configuration options which define the execution
- environment of spawned processes.</para>
-
- <para>This man page lists the configuration options
- shared by these four unit types. See
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for the common options of all unit configuration
- files, and
- <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>
- and
- <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for more information on the specific unit
- configuration files. The execution specific
- configuration options are configured in the [Service],
- [Socket], [Mount] resp. [Swap] section, depending on the unit
- type.</para>
- </refsect1>
-
- <refsect1>
- <title>Options</title>
-
- <variablelist>
-
- <varlistentry>
- <term><varname>WorkingDirectory=</varname></term>
-
- <listitem><para>Takes an absolute
- directory path. Sets the working
- directory for executed
- processes.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>RootDirectory=</varname></term>
-
- <listitem><para>Takes an absolute
- directory path. Sets the root
- directory for executed processes, with
- the
- <citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- system call. If this is used it must
- be ensured that the process and all
- its auxiliary files are available in
- the <function>chroot()</function>
- jail.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>User=</varname></term>
- <term><varname>Group=</varname></term>
-
- <listitem><para>Sets the Unix user
- resp. group the processes are executed
- as. Takes a single user resp. group
- name or ID as argument. If no group is
- set the default group of the user is
- chosen.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SupplementaryGroups=</varname></term>
-
- <listitem><para>Sets the supplementary
- Unix groups the processes are executed
- as. This takes a space separated list
- of group names or IDs. This option may
- be specified more than once in which
- case all listed groups are set as
- supplementary groups. This option does
- not override but extends the list of
- supplementary groups configured in the
- system group database for the
- user.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Nice=</varname></term>
-
- <listitem><para>Sets the default nice
- level (scheduling priority) for
- executed processes. Takes an integer
- between -20 (highest priority) and 19
- (lowest priority). See
- <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>OOMScoreAdjust=</varname></term>
-
- <listitem><para>Sets the adjustment
- level for the Out-Of-Memory killer for
- executed processes. Takes an integer
- between -1000 (to disable OOM killing
- for this process) and 1000 (to make
- killing of this process under memory
- pressure very likely). See <ulink
- url="http://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>IOSchedulingClass=</varname></term>
-
- <listitem><para>Sets the IO scheduling
- class for executed processes. Takes an
- integer between 0 and 3 or one of the
- strings <option>none</option>,
- <option>realtime</option>,
- <option>best-effort</option> or
- <option>idle</option>. See
- <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>IOSchedulingPriority=</varname></term>
-
- <listitem><para>Sets the IO scheduling
- priority for executed processes. Takes
- an integer between 0 (highest
- priority) and 7 (lowest priority). The
- available priorities depend on the
- selected IO scheduling class (see
- above). See
- <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUSchedulingPolicy=</varname></term>
-
- <listitem><para>Sets the CPU
- scheduling policy for executed
- processes. Takes one of
- <option>other</option>,
- <option>batch</option>,
- <option>idle</option>,
- <option>fifo</option> or
- <option>rr</option>. See
- <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUSchedulingPriority=</varname></term>
-
- <listitem><para>Sets the CPU
- scheduling priority for executed
- processes. Takes an integer between 1
- (lowest priority) and 99 (highest
- priority). The available priority
- range depends on the selected CPU
- scheduling policy (see above). See
- <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUSchedulingResetOnFork=</varname></term>
-
- <listitem><para>Takes a boolean
- argument. If true elevated CPU
- scheduling priorities and policies
- will be reset when the executed
- processes fork, and can hence not leak
- into child processes. See
- <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details. Defaults to false.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUAffinity=</varname></term>
-
- <listitem><para>Controls the CPU
- affinity of the executed
- processes. Takes a space-separated
- list of CPU indexes. See
- <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
- processes. Takes a space-separated
- list of variable 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. See
- <citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details.</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 and lines
- starting with ; or # will be ignored,
- which may be used for commenting. The
- parser strips leading and
- trailing whitespace from the values
- of assignments, unless you use
- double quotes (").
- The
- argument passed should be an absolute
- file name, optionally prefixed with
- "-", which indicates that if the file
- does not exist it won't be read and no
- error or warning message is
- logged. The files listed with this
- directive will be read shortly before
- the process is executed. 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>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>. 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. 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.
- <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. <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. 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><refentrytitle>inetd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- daemon. 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>syslog</option>,
- <option>kmsg</option>,
- <option>journal</option>,
- <option>syslog+console</option>,
- <option>kmsg+console</option>,
- <option>journal+console</option> or
- <option>socket</option>. If set to
- <option>inherit</option> the file
- descriptor of standard input is
- duplicated for standard output. If set
- to <option>null</option> standard
- output will be connected to
- <filename>/dev/null</filename>,
- i.e. everything written to it will be
- lost. If set to <option>tty</option>
- standard output will be connected 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. <option>syslog</option>
- connects standard output to the
- <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- system syslog
- service. <option>kmsg</option>
- connects it with the kernel log buffer
- which is accessible via
- <citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <option>journal</option>
- connects it 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 is implicitly stored
- in the journal as well, those options
- are hence supersets of this
- one). <option>syslog+console</option>,
- <option>journal+console</option> and
- <option>kmsg+console</option> work
- similarly but copy the output to the
- system console as
- well. <option>socket</option> connects
- standard output to a socket from
- socket activation, semantics are
- similar to the respective option of
- <varname>StandardInput=</varname>.
- This setting defaults to the value set
- with
- <option>DefaultStandardOutput=</option>
- in
- <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- which defaults to
- <option>journal</option>.</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.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- which defaults to
- <option>inherit</option>.</para></listitem>
- </varlistentry>
- <varlistentry>
- <term><varname>TTYPath=</varname></term>
- <listitem><para>Sets the terminal
- device node to use if standard input,
- output or stderr 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 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 syslog 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> or
- <option>kmsg</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><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>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><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> or
- <option>kmsg</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>These settings control
- various resource limits for executed
- processes. See
- <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details. Use the string
- <varname>infinity</varname> to
- configure no limit on a specific
- resource.</para></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><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for details.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>TCPWrapName=</varname></term>
- <listitem><para>If this is a
- socket-activated service this sets the
- tcpwrap service name to check the
- permission for the current connection
- with. This is only useful in
- conjunction with socket-activated
- services, and stream sockets (TCP) in
- particular. It has no effect on other
- socket types (e.g. datagram/UDP) and
- on processes unrelated to socket-based
- activation. If the tcpwrap
- verification fails daemon start-up
- will fail and the connection is
- terminated. See
- <citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- for details. Note that this option may
- be used to do access control checks
- only. Shell commands and commands
- described in
- <citerefentry><refentrytitle>hosts_options</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- are not supported.</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><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details. Takes a whitespace
- separated list of capability names as
- read by
- <citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- Capabilities listed will be included
- in the bounding set, all others are
- removed. If the list of capabilities
- is prefixed with ~ all but the listed
- capabilities will be included, the
- effect of the assignment
- inverted. Note that this option also
- effects the respective capabilities in
- the effective, permitted and
- inheritable capability sets, on top of
- what <varname>Capabilities=</varname>
- does. 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.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>SecureBits=</varname></term>
- <listitem><para>Controls the secure
- bits set for the executed process. See
- <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details. Takes a list of strings:
- <option>keep-caps</option>,
- <option>keep-caps-locked</option>,
- <option>no-setuid-fixup</option>,
- <option>no-setuid-fixup-locked</option>,
- <option>noroot</option> and/or
- <option>noroot-locked</option>.
- </para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>Capabilities=</varname></term>
- <listitem><para>Controls the
- <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- set for the executed process. Take a
- capability string describing the
- effective, permitted and inherited
- capability sets as documented in
- <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
- Note that these capability sets are
- usually influenced by the capabilities
- attached to the executed file. Due to
- that
- <varname>CapabilityBoundingSet=</varname>
- is probably the much more useful
- setting.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroup=</varname></term>
-
- <listitem><para>Controls the control
- groups the executed processes shall be
- made members of. Takes a
- space-separated list of cgroup
- identifiers. A cgroup identifier has a
- format like
- <filename>cpu:/foo/bar</filename>,
- where "cpu" identifies the kernel
- control group controller used, and
- <filename>/foo/bar</filename> is the
- control group path. The controller
- name and ":" may be omitted in which
- case the named systemd control group
- hierarchy is implied. Alternatively,
- the path and ":" may be omitted, in
- which case the default control group
- path for this unit is implied. This
- option may be used to place executed
- processes in arbitrary groups in
- arbitrary hierarchies -- which can be
- configured externally with additional
- execution limits. By default systemd
- will place all executed processes in
- separate per-unit control groups
- (named after the unit) in the systemd
- named hierarchy. Since every process
- can be in one group per hierarchy only
- overriding the control group path in
- the named systemd hierarchy will
- disable automatic placement in the
- default group. This option is
- primarily intended to place executed
- processes in specific paths in
- specific kernel controller
- hierarchies. It is however not
- recommended to manipulate the service
- control group path in the systemd
- named hierarchy. For details about
- control groups see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupModify=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, the control groups
- created for this unit will be owned by
- the user specified with
- <varname>User=</varname> (and the
- appropriate group), and he/she can create
- subgroups as well as add processes to
- the group.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupPersistent=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, the control groups
- created for this unit will be marked
- to be persistent, i.e. systemd will
- not remove them when stopping the
- unit. The default is false, meaning
- that the control groups will be
- removed when the unit is stopped. For
- details about the semantics of this
- logic see <ulink
- url="http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups">PaxControlGroups</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupAttribute=</varname></term>
-
- <listitem><para>Set a specific control
- group attribute for executed
- processes, and (if needed) add the the
- executed processes to a cgroup in the
- hierarchy of the controller the
- attribute belongs to. Takes two
- space-separated arguments: the
- attribute name (syntax is
- <literal>cpu.shares</literal> where
- <literal>cpu</literal> refers to a
- specific controller and
- <literal>shares</literal> to the
- attribute name), and the attribute
- value. Example:
- <literal>ControlGroupAttribute=cpu.shares
- 512</literal>. If this option is used
- for an attribute that belongs to a
- kernel controller hierarchy the unit
- is not already configured to be added
- to (for example via the
- <literal>ControlGroup=</literal>
- option) then the unit will be added to
- the controller and the default unit
- cgroup path is implied. Thus, using
- <varname>ControlGroupAttribute=</varname>
- is in most case sufficient to make use
- of control group enforcements,
- explicit
- <varname>ControlGroup=</varname> are
- only necessary in case the implied
- default control group path for a
- service is not desirable. For details
- about control group attributes see
- <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>. This
- option may appear more than once, in
- order to set multiple control group
- attributes.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUShares=</varname></term>
-
- <listitem><para>Assign the specified
- overall CPU time shares to the
- processes executed. Takes an integer
- value. This controls the
- <literal>cpu.shares</literal> control
- group attribute, which defaults to
- 1024. For details about this control
- group attribute see <ulink
- url="http://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>MemoryLimit=</varname></term>
- <term><varname>MemorySoftLimit=</varname></term>
-
- <listitem><para>Limit the overall memory usage
- of the executed processes to a certain
- size. Takes a memory size in bytes. If
- the value is suffixed with K, M, G or
- T the specified memory size is parsed
- as Kilobytes, Megabytes, Gigabytes,
- resp. Terabytes (to the base
- 1024). This controls the
- <literal>memory.limit_in_bytes</literal>
- and
- <literal>memory.soft_limit_in_bytes</literal>
- control group attributes. For details
- about these control group attributes
- see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>DeviceAllow=</varname></term>
- <term><varname>DeviceDeny=</varname></term>
-
- <listitem><para>Control access to
- specific device nodes by the executed processes. Takes two
- space separated strings: a device node
- path (such as
- <filename>/dev/null</filename>)
- followed by a combination of r, w, m
- to control reading, writing resp.
- creating of the specific device node
- by the unit. This controls the
- <literal>devices.allow</literal>
- and
- <literal>devices.deny</literal>
- control group attributes. For details
- about these control group attributes
- see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/devices.txt">devices.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BlockIOWeight=</varname></term>
-
- <listitem><para>Set the default or
- per-device overall block IO weight
- value for the executed
- processes. Takes either a single
- weight value (between 10 and 1000) to
- set the default block IO weight, or a
- space separated pair of a file path
- and a weight value to specify the
- device specific weight value (Example:
- "/dev/sda 500"). The file path may be
- specified as path to a block device
- node or as any other file in which
- case the backing block device of the
- file system of the file is
- determined. This controls the
- <literal>blkio.weight</literal> and
- <literal>blkio.weight_device</literal>
- control group attributes, which
- default to 1000. Use this option
- multiple times to set weights for
- multiple devices. For details about
- these control group attributes see
- <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BlockIOReadBandwidth=</varname></term>
- <term><varname>BlockIOWriteBandwidth=</varname></term>
-
- <listitem><para>Set the per-device
- overall block IO bandwith limit for
- the executed processes. Takes a space
- separated pair of a file path and a
- bandwith value (in bytes per second)
- to specify the device specific
- bandwidth. The file path may be
- specified as path to a block device
- node or as any other file in which
- case the backing block device of the
- file system of the file is determined.
- If the bandwith is suffixed with K, M,
- G, or T the specified bandwith is
- parsed as Kilobytes, Megabytes,
- Gigabytes, resp. Terabytes (Example:
- "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0
- 5M"). This controls the
- <literal>blkio.read_bps_device</literal>
- and
- <literal>blkio.write_bps_device</literal>
- control group attributes. Use this
- option multiple times to set bandwith
- limits for multiple devices. For
- details about these control group
- attributes see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ReadWriteDirectories=</varname></term>
- <term><varname>ReadOnlyDirectories=</varname></term>
- <term><varname>InaccessibleDirectories=</varname></term>
-
- <listitem><para>Sets up a new
- file-system name space 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 absolute
- directory paths. Directories listed in
- <varname>ReadWriteDirectories=</varname>
- are accessible from within the
- namespace with the same access rights
- as from outside. Directories listed in
- <varname>ReadOnlyDirectories=</varname>
- are accessible for reading only,
- writing will be refused even if the
- usual file access controls would
- permit this. Directories listed in
- <varname>InaccessibleDirectories=</varname>
- will be made inaccessible for processes
- inside the namespace. Note that
- restricting access with these options
- does not extend to submounts of a
- directory. You must list submounts
- separately in these settings to
- ensure the same limited access. These
- options may be specified more than
- once in which case all directories
- listed will have limited access from
- within the
- 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 a private
- <filename>/tmp</filename> directory
- 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>
- impossible. Defaults to
- false.</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.</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 namespaces set up with
- <varname>ReadWriteDirectories=</varname>,
- <varname>ReadOnlyDirectories=</varname>
- and
- <varname>InaccessibleDirectories=</varname>
- receive or propagate new mounts
- from/to the main namespace. See
- <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- for details. Defaults to
- <option>shared</option>, i.e. the new
- namespace will both receive new mount
- points from the main namespace as well
- as propagate new mounts to
- it.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>UtmpIdentifier=</varname></term>
-
- <listitem><para>Takes a a four
- character identifier string for an
- utmp/wtmp entry for this service. This
- should only be set for services such
- as <command>getty</command>
- implementations where utmp/wtmp
- entries must be created and cleared
- before and after execution. 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>IgnoreSIGPIPE=</varname></term>
-
- <listitem><para>Takes a boolean
- argument. If true causes SIGPIPE to be
- ignored in the executed
- process. Defaults to true, since
- SIGPIPE generally is useful only in
- shell pipelines.</para></listitem>
- </varlistentry>
-
- </variablelist>
- </refsect1>
-
- <refsect1>
- <title>See Also</title>
- <para>
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</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>
- </para>
- </refsect1>
+ <refentryinfo>
+ <title>systemd.exec</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>Developer</contrib>
+ <firstname>Lennart</firstname>
+ <surname>Poettering</surname>
+ <email>lennart@poettering.net</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd.exec</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd.exec</refname>
+ <refpurpose>Execution environment configuration</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename><replaceable>service</replaceable>.service</filename>,
+ <filename><replaceable>socket</replaceable>.socket</filename>,
+ <filename><replaceable>mount</replaceable>.mount</filename>,
+ <filename><replaceable>swap</replaceable>.swap</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>Unit configuration files for services, sockets, mount
+ points, and swap devices share a subset of configuration options
+ which define the execution environment of spawned
+ processes.</para>
+
+ <para>This man page lists the configuration options shared by
+ these four unit types. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for the common options of all unit configuration files, and
+ <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>,
+ and
+ <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more information on the specific unit configuration files. The
+ execution specific configuration options are configured in the
+ [Service], [Socket], [Mount], or [Swap] sections, depending on the
+ unit type.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Options</title>
+
+ <variablelist class='unit-directives'>
+
+ <varlistentry>
+ <term><varname>WorkingDirectory=</varname></term>
+
+ <listitem><para>Takes an absolute directory path. Sets the
+ working directory for executed processes. If not set, defaults
+ to the root directory when systemd is running as a system
+ instance and the respective user's home directory if run as
+ user.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RootDirectory=</varname></term>
+
+ <listitem><para>Takes an absolute directory path. Sets the
+ root directory for executed processes, with the
+ <citerefentry project='man-pages'><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ system call. If this is used, it must be ensured that the
+ process and all its auxiliary files are available in the
+ <function>chroot()</function> jail.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>User=</varname></term>
+ <term><varname>Group=</varname></term>
+
+ <listitem><para>Sets the Unix user or group that the processes
+ are executed as, respectively. Takes a single user or group
+ name or ID as argument. If no group is set, the default group
+ of the user is chosen.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>SupplementaryGroups=</varname></term>
+
+ <listitem><para>Sets the supplementary Unix groups the
+ processes are executed as. This takes a space-separated list
+ of group names or IDs. This option may be specified more than
+ once in which case all listed groups are set as supplementary
+ groups. When the empty string is assigned the list of
+ supplementary groups is reset, and all assignments prior to
+ this one will have no effect. In any way, this option does not
+ override, but extends the list of supplementary groups
+ configured in the system group database for the
+ user.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Nice=</varname></term>
+
+ <listitem><para>Sets the default nice level (scheduling
+ priority) for executed processes. Takes an integer between -20
+ (highest priority) and 19 (lowest priority). See
+ <citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>OOMScoreAdjust=</varname></term>
+
+ <listitem><para>Sets the adjustment level for the
+ Out-Of-Memory killer for executed processes. Takes an integer
+ between -1000 (to disable OOM killing for this process) and
+ 1000 (to make killing of this process under memory pressure
+ very likely). See <ulink
+ url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IOSchedulingClass=</varname></term>
+
+ <listitem><para>Sets the IO scheduling class for executed
+ processes. Takes an integer between 0 and 3 or one of the
+ strings <option>none</option>, <option>realtime</option>,
+ <option>best-effort</option> or <option>idle</option>. See
+ <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>IOSchedulingPriority=</varname></term>
+
+ <listitem><para>Sets the IO scheduling priority for executed
+ processes. Takes an integer between 0 (highest priority) and 7
+ (lowest priority). The available priorities depend on the
+ selected IO scheduling class (see above). See
+ <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUSchedulingPolicy=</varname></term>
+
+ <listitem><para>Sets the CPU scheduling policy for executed
+ processes. Takes one of
+ <option>other</option>,
+ <option>batch</option>,
+ <option>idle</option>,
+ <option>fifo</option> or
+ <option>rr</option>. See
+ <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUSchedulingPriority=</varname></term>
+
+ <listitem><para>Sets the CPU scheduling priority for executed
+ processes. The available priority range depends on the
+ selected CPU scheduling policy (see above). For real-time
+ scheduling policies an integer between 1 (lowest priority) and
+ 99 (highest priority) can be used. See
+ <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details. </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUSchedulingResetOnFork=</varname></term>
+
+ <listitem><para>Takes a boolean argument. If true, elevated
+ CPU scheduling priorities and policies will be reset when the
+ executed processes fork, and can hence not leak into child
+ processes. See
+ <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details. Defaults to false.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>CPUAffinity=</varname></term>
+
+ <listitem><para>Controls the CPU affinity of the executed
+ processes. Takes a space-separated list of CPU indices. This
+ option may be specified more than once in which case the
+ specified CPU affinity masks are merged. If the empty string
+ is assigned, the mask is reset, all assignments prior to this
+ will have no effect. See
+ <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
+ processes. Takes a space-separated list of variable
+ 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 and 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). 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>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><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>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>.</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>.</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>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>These settings set both soft and hard limits
+ of various resources for executed processes. See
+ <citerefentry><refentrytitle>setrlimit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details. Use the string <varname>infinity</varname> to
+ configure no limit on a specific resource.</para></listitem>
+
+ <table>
+ <title>Limit directives and their equivalent with ulimit</title>
+
+ <tgroup cols='2'>
+ <colspec colname='directive' />
+ <colspec colname='equivalent' />
+ <thead>
+ <row>
+ <entry>Directive</entry>
+ <entry>ulimit equivalent</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>LimitCPU</entry>
+ <entry>ulimit -t</entry>
+ </row>
+ <row>
+ <entry>LimitFSIZE</entry>
+ <entry>ulimit -f</entry>
+ </row>
+ <row>
+ <entry>LimitDATA</entry>
+ <entry>ulimit -d</entry>
+ </row>
+ <row>
+ <entry>LimitSTACK</entry>
+ <entry>ulimit -s</entry>
+ </row>
+ <row>
+ <entry>LimitCORE</entry>
+ <entry>ulimit -c</entry>
+ </row>
+ <row>
+ <entry>LimitRSS</entry>
+ <entry>ulimit -m</entry>
+ </row>
+ <row>
+ <entry>LimitNOFILE</entry>
+ <entry>ulimit -n</entry>
+ </row>
+ <row>
+ <entry>LimitAS</entry>
+ <entry>ulimit -v</entry>
+ </row>
+ <row>
+ <entry>LimitNPROC</entry>
+ <entry>ulimit -u</entry>
+ </row>
+ <row>
+ <entry>LimitMEMLOCK</entry>
+ <entry>ulimit -l</entry>
+ </row>
+ <row>
+ <entry>LimitLOCKS</entry>
+ <entry>ulimit -x</entry>
+ </row>
+ <row>
+ <entry>LimitSIGPENDING</entry>
+ <entry>ulimit -i</entry>
+ </row>
+ <row>
+ <entry>LimitMSGQUEUE</entry>
+ <entry>ulimit -q</entry>
+ </row>
+ <row>
+ <entry>LimitNICE</entry>
+ <entry>ulimit -e</entry>
+ </row>
+ <row>
+ <entry>LimitRTPRIO</entry>
+ <entry>ulimit -r</entry>
+ </row>
+ <row>
+ <entry>LimitRTTIME</entry>
+ <entry>No equivalent</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </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><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, on top
+ of what <varname>Capabilities=</varname> does. 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.</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. See
+ <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Capabilities=</varname></term>
+ <listitem><para>Controls the
+ <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ set for the executed process. Take a capability string
+ describing the effective, permitted and inherited capability
+ sets as documented in
+ <citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ Note that these capability sets are usually influenced (and
+ filtered) by the capabilities attached to the executed file.
+ Due to that <varname>CapabilityBoundingSet=</varname> is
+ probably a much more useful setting.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>ReadWriteDirectories=</varname></term>
+ <term><varname>ReadOnlyDirectories=</varname></term>
+ <term><varname>InaccessibleDirectories=</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 absolute directory
+ paths. Directories listed in
+ <varname>ReadWriteDirectories=</varname> are accessible from
+ within the namespace with the same access rights as from
+ outside. Directories listed in
+ <varname>ReadOnlyDirectories=</varname> are accessible for
+ reading only, writing will be refused even if the usual file
+ access controls would permit this. Directories listed in
+ <varname>InaccessibleDirectories=</varname> will be made
+ inaccessible for processes inside the namespace. Note that
+ restricting access with these options does not extend to
+ submounts of a directory that are created later on. These
+ options may be specified more than once in which case all
+ directories 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>ReadOnlyDirectories=</varname>
+ and
+ <varname>InaccessibleDirectories=</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.</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.</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>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> and <filename>/run/user</filename>
+ are made inaccessible and empty for processes invoked by this
+ unit. If set to <literal>read-only</literal>, the two
+ 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><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>ReadOnlyDirectories=</varname>,
+ <varname>InaccessibleDirectories=</varname> and
+ <varname>ReadWriteDirectories=</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 utmp/wtmp entry for this service. This should only be set
+ for services such as <command>getty</command> implementations
+ where utmp/wtmp entries must be created and cleared before and
+ after execution. 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>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. See
+ <citerefentry><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. </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
+ processes 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.</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 and this option is used,
+ <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.</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></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 and this option is
+ used, <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><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 and this option
+ is used, <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.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Personality=</varname></term>
+
+ <listitem><para>Controls which kernel architecture
+ <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ shall report, when invoked by unit processes. Takes one of
+ <constant>x86</constant> and <constant>x86-64</constant>. This
+ 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>$XDG_RUNTIME_DIR</varname> (for user services) when
+ the unit is started, and removed when the unit is stopped. The
+ directories will have the access mode specified in
+ <varname>RuntimeDirectoryMode=</varname>, and will be owned by
+ the user and group specified in <varname>User=</varname> and
+ <varname>Group=</varname>. Use this to manage one or more
+ runtime directories of the unit and bind their lifetime to the
+ daemon runtime. The specified directory names must be
+ relative, and may not include a <literal>/</literal>, i.e.
+ must refer to simple directories to create or remove. This is
+ particularly useful for unprivileged daemons that cannot
+ create runtime directories in <filename>/run</filename> due to
+ lack of privileges, and to make sure the runtime directory is
+ cleaned up automatically after use. For runtime directories
+ that require more complex or different configuration or
+ lifetime guarantees, please consider using
+ <citerefentry><refentrytitle>tmpfiles.d</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Environment variables in spawned processes</title>
+
+ <para>Processes started by the system are executed in a clean
+ environment in which select variables listed below are set. System
+ processes started by systemd do not inherit variables from PID 1,
+ but processes started by user systemd instances inherit all
+ environment variables from the user systemd instance.
+ </para>
+
+ <variablelist class='environment-variables'>
+ <varlistentry>
+ <term><varname>$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>$LANG</varname></term>
+
+ <listitem><para>Locale. Can be set in
+ <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ or on the kernel command line (see
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>).
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$USER</varname></term>
+ <term><varname>$LOGNAME</varname></term>
+ <term><varname>$HOME</varname></term>
+ <term><varname>$SHELL</varname></term>
+
+ <listitem><para>User name (twice), home directory, and the
+ login shell. The variables are set for the units that have
+ <varname>User=</varname> set, which includes user
+ <command>systemd</command> instances. See
+ <citerefentry><refentrytitle>passwd</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$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>$LISTEN_PID</varname></term>
+
+ <listitem><para>Information about file descriptors passed to a
+ service for socket activation. See
+ <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$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>
+ </variablelist>
+
+ <para>Additional variables may be configured by the following
+ means: for processes spawned in specific units, use the
+ <varname>Environment=</varname> and
+ <varname>EnvironmentFile=</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.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>