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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>systemd.exec</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
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</style><a href="index.html">Index </a>·
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<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 219</span><hr><div class="refentry"><a name="systemd.exec"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd.exec — Execution environment configuration</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename"><em class="replaceable"><code>service</code></em>.service</code>,
<code class="filename"><em class="replaceable"><code>socket</code></em>.socket</code>,
<code class="filename"><em class="replaceable"><code>mount</code></em>.mount</code>,
<code class="filename"><em class="replaceable"><code>swap</code></em>.swap</code></p></div><div class="refsect1"><a name="idm140278903646480"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description"></a></h2><p>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.</p><p>This man page lists the configuration options shared by
these four unit types. See
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
for the common options of all unit configuration files, and
<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
<a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>,
<a href="systemd.swap.html"><span class="citerefentry"><span class="refentrytitle">systemd.swap</span>(5)</span></a>,
and
<a href="systemd.mount.html"><span class="citerefentry"><span class="refentrytitle">systemd.mount</span>(5)</span></a>
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.</p></div><div class="refsect1"><a name="idm140278903640256"></a><h2 id="Options">Options<a class="headerlink" title="Permalink to this headline" href="#Options"></a></h2><div class="variablelist"><dl class="variablelist"><dt id="WorkingDirectory="><span class="term"><code class="varname">WorkingDirectory=</code></span><a class="headerlink" title="Permalink to this term" href="#WorkingDirectory="></a></dt><dd><p>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.</p></dd><dt id="RootDirectory="><span class="term"><code class="varname">RootDirectory=</code></span><a class="headerlink" title="Permalink to this term" href="#RootDirectory="></a></dt><dd><p>Takes an absolute directory path. Sets the
root directory for executed processes, with the
<a href="http://man7.org/linux/man-pages/man2/chroot.2.html"><span class="citerefentry"><span class="refentrytitle">chroot</span>(2)</span></a>
system call. If this is used, it must be ensured that the
process and all its auxiliary files are available in the
<code class="function">chroot()</code> jail.</p></dd><dt id="User="><span class="term"><code class="varname">User=</code>, </span><span class="term"><code class="varname">Group=</code></span><a class="headerlink" title="Permalink to this term" href="#User="></a></dt><dd><p>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.</p></dd><dt id="SupplementaryGroups="><span class="term"><code class="varname">SupplementaryGroups=</code></span><a class="headerlink" title="Permalink to this term" href="#SupplementaryGroups="></a></dt><dd><p>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.</p></dd><dt id="Nice="><span class="term"><code class="varname">Nice=</code></span><a class="headerlink" title="Permalink to this term" href="#Nice="></a></dt><dd><p>Sets the default nice level (scheduling
priority) for executed processes. Takes an integer between -20
(highest priority) and 19 (lowest priority). See
<a href="http://man7.org/linux/man-pages/man2/setpriority.2.html"><span class="citerefentry"><span class="refentrytitle">setpriority</span>(2)</span></a>
for details.</p></dd><dt id="OOMScoreAdjust="><span class="term"><code class="varname">OOMScoreAdjust=</code></span><a class="headerlink" title="Permalink to this term" href="#OOMScoreAdjust="></a></dt><dd><p>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 <a class="ulink" href="https://www.kernel.org/doc/Documentation/filesystems/proc.txt" target="_top">proc.txt</a>
for details.</p></dd><dt id="IOSchedulingClass="><span class="term"><code class="varname">IOSchedulingClass=</code></span><a class="headerlink" title="Permalink to this term" href="#IOSchedulingClass="></a></dt><dd><p>Sets the IO scheduling class for executed
processes. Takes an integer between 0 and 3 or one of the
strings <code class="option">none</code>, <code class="option">realtime</code>,
<code class="option">best-effort</code> or <code class="option">idle</code>. See
<a href="http://man7.org/linux/man-pages/man2/ioprio_set.2.html"><span class="citerefentry"><span class="refentrytitle">ioprio_set</span>(2)</span></a>
for details.</p></dd><dt id="IOSchedulingPriority="><span class="term"><code class="varname">IOSchedulingPriority=</code></span><a class="headerlink" title="Permalink to this term" href="#IOSchedulingPriority="></a></dt><dd><p>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
<a href="http://man7.org/linux/man-pages/man2/ioprio_set.2.html"><span class="citerefentry"><span class="refentrytitle">ioprio_set</span>(2)</span></a>
for details.</p></dd><dt id="CPUSchedulingPolicy="><span class="term"><code class="varname">CPUSchedulingPolicy=</code></span><a class="headerlink" title="Permalink to this term" href="#CPUSchedulingPolicy="></a></dt><dd><p>Sets the CPU scheduling policy for executed
processes. Takes one of
<code class="option">other</code>,
<code class="option">batch</code>,
<code class="option">idle</code>,
<code class="option">fifo</code> or
<code class="option">rr</code>. See
<a href="http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html"><span class="citerefentry"><span class="refentrytitle">sched_setscheduler</span>(2)</span></a>
for details.</p></dd><dt id="CPUSchedulingPriority="><span class="term"><code class="varname">CPUSchedulingPriority=</code></span><a class="headerlink" title="Permalink to this term" href="#CPUSchedulingPriority="></a></dt><dd><p>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
<a href="http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html"><span class="citerefentry"><span class="refentrytitle">sched_setscheduler</span>(2)</span></a>
for details. </p></dd><dt id="CPUSchedulingResetOnFork="><span class="term"><code class="varname">CPUSchedulingResetOnFork=</code></span><a class="headerlink" title="Permalink to this term" href="#CPUSchedulingResetOnFork="></a></dt><dd><p>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
<a href="http://man7.org/linux/man-pages/man2/sched_setscheduler.2.html"><span class="citerefentry"><span class="refentrytitle">sched_setscheduler</span>(2)</span></a>
for details. Defaults to false.</p></dd><dt id="CPUAffinity="><span class="term"><code class="varname">CPUAffinity=</code></span><a class="headerlink" title="Permalink to this term" href="#CPUAffinity="></a></dt><dd><p>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
<a href="http://man7.org/linux/man-pages/man2/sched_setaffinity.2.html"><span class="citerefentry"><span class="refentrytitle">sched_setaffinity</span>(2)</span></a>
for details.</p></dd><dt id="UMask="><span class="term"><code class="varname">UMask=</code></span><a class="headerlink" title="Permalink to this term" href="#UMask="></a></dt><dd><p>Controls the file mode creation mask. Takes an
access mode in octal notation. See
<a href="http://man7.org/linux/man-pages/man2/umask.2.html"><span class="citerefentry"><span class="refentrytitle">umask</span>(2)</span></a>
for details. Defaults to 0022.</p></dd><dt id="Environment="><span class="term"><code class="varname">Environment=</code></span><a class="headerlink" title="Permalink to this term" href="#Environment="></a></dt><dd><p>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.</p><p>Example:
</p><pre class="programlisting">Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"</pre><p>
gives three variables "<code class="literal">VAR1</code>",
"<code class="literal">VAR2</code>", "<code class="literal">VAR3</code>"
with the values "<code class="literal">word1 word2</code>",
"<code class="literal">word3</code>", "<code class="literal">$word 5 6</code>".
</p><p>
See
<a href="http://man7.org/linux/man-pages/man7/environ.7.html"><span class="citerefentry"><span class="refentrytitle">environ</span>(7)</span></a>
for details about environment variables.</p></dd><dt id="EnvironmentFile="><span class="term"><code class="varname">EnvironmentFile=</code></span><a class="headerlink" title="Permalink to this term" href="#EnvironmentFile="></a></dt><dd><p>Similar to <code class="varname">Environment=</code> 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 (").</p><p>The argument passed should be an absolute filename or
wildcard expression, optionally prefixed with
"<code class="literal">-</code>", 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.</p><p>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
<code class="varname">Environment=</code>. 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.</p></dd><dt id="StandardInput="><span class="term"><code class="varname">StandardInput=</code></span><a class="headerlink" title="Permalink to this term" href="#StandardInput="></a></dt><dd><p>Controls where file descriptor 0 (STDIN) of
the executed processes is connected to. Takes one of
<code class="option">null</code>,
<code class="option">tty</code>,
<code class="option">tty-force</code>,
<code class="option">tty-fail</code> or
<code class="option">socket</code>.</p><p>If <code class="option">null</code> is selected, standard input
will be connected to <code class="filename">/dev/null</code>, i.e. all
read attempts by the process will result in immediate
EOF.</p><p>If <code class="option">tty</code> is selected, standard input is
connected to a TTY (as configured by
<code class="varname">TTYPath=</code>, 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.</p><p><code class="option">tty-force</code> is similar to
<code class="option">tty</code>, but the executed process is forcefully
and immediately made the controlling process of the terminal,
potentially removing previous controlling processes from the
terminal.</p><p><code class="option">tty-fail</code> is similar to
<code class="option">tty</code> but if the terminal already has a
controlling process start-up of the executed process
fails.</p><p>The <code class="option">socket</code> option is only valid in
socket-activated services, and only when the socket
configuration file (see
<a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>
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
<a href="inetd.html"><span class="citerefentry"><span class="refentrytitle">inetd</span>(8)</span></a>
daemon.</p><p>This setting defaults to
<code class="option">null</code>.</p></dd><dt id="StandardOutput="><span class="term"><code class="varname">StandardOutput=</code></span><a class="headerlink" title="Permalink to this term" href="#StandardOutput="></a></dt><dd><p>Controls where file descriptor 1 (STDOUT) of
the executed processes is connected to. Takes one of
<code class="option">inherit</code>,
<code class="option">null</code>,
<code class="option">tty</code>,
<code class="option">journal</code>,
<code class="option">syslog</code>,
<code class="option">kmsg</code>,
<code class="option">journal+console</code>,
<code class="option">syslog+console</code>,
<code class="option">kmsg+console</code> or
<code class="option">socket</code>.</p><p><code class="option">inherit</code> duplicates the file descriptor
of standard input for standard output.</p><p><code class="option">null</code> connects standard output to
<code class="filename">/dev/null</code>, i.e. everything written to it
will be lost.</p><p><code class="option">tty</code> connects standard output to a tty
(as configured via <code class="varname">TTYPath=</code>, 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.</p><p><code class="option">journal</code> connects standard output with
the journal which is accessible via
<a href="journalctl.html"><span class="citerefentry"><span class="refentrytitle">journalctl</span>(1)</span></a>.
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.</p><p><code class="option">syslog</code> connects standard output to the
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
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 <code class="option">journal</code>.</p><p><code class="option">kmsg</code> connects standard output with the
kernel log buffer which is accessible via
<a href="http://man7.org/linux/man-pages/man1/dmesg.1.html"><span class="citerefentry"><span class="refentrytitle">dmesg</span>(1)</span></a>,
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 <code class="option">journal</code>.</p><p><code class="option">journal+console</code>,
<code class="option">syslog+console</code> and
<code class="option">kmsg+console</code> work in a similar way as the
three options above but copy the output to the system console
as well.</p><p><code class="option">socket</code> connects standard output to a
socket acquired via socket activation. The semantics are
similar to the same option of
<code class="varname">StandardInput=</code>.</p><p>This setting defaults to the value set with
<code class="option">DefaultStandardOutput=</code> in
<a href="systemd-system.conf.html"><span class="citerefentry"><span class="refentrytitle">systemd-system.conf</span>(5)</span></a>,
which defaults to <code class="option">journal</code>.</p></dd><dt id="StandardError="><span class="term"><code class="varname">StandardError=</code></span><a class="headerlink" title="Permalink to this term" href="#StandardError="></a></dt><dd><p>Controls where file descriptor 2 (STDERR) of
the executed processes is connected to. The available options
are identical to those of <code class="varname">StandardOutput=</code>,
with one exception: if set to <code class="option">inherit</code> the
file descriptor used for standard output is duplicated for
standard error. This setting defaults to the value set with
<code class="option">DefaultStandardError=</code> in
<a href="systemd-system.conf.html"><span class="citerefentry"><span class="refentrytitle">systemd-system.conf</span>(5)</span></a>,
which defaults to <code class="option">inherit</code>.</p></dd><dt id="TTYPath="><span class="term"><code class="varname">TTYPath=</code></span><a class="headerlink" title="Permalink to this term" href="#TTYPath="></a></dt><dd><p>Sets the terminal device node to use if
standard input, output, or error are connected to a TTY (see
above). Defaults to
<code class="filename">/dev/console</code>.</p></dd><dt id="TTYReset="><span class="term"><code class="varname">TTYReset=</code></span><a class="headerlink" title="Permalink to this term" href="#TTYReset="></a></dt><dd><p>Reset the terminal device specified with
<code class="varname">TTYPath=</code> before and after execution.
Defaults to "<code class="literal">no</code>".</p></dd><dt id="TTYVHangup="><span class="term"><code class="varname">TTYVHangup=</code></span><a class="headerlink" title="Permalink to this term" href="#TTYVHangup="></a></dt><dd><p>Disconnect all clients which have opened the
terminal device specified with <code class="varname">TTYPath=</code>
before and after execution. Defaults to
"<code class="literal">no</code>".</p></dd><dt id="TTYVTDisallocate="><span class="term"><code class="varname">TTYVTDisallocate=</code></span><a class="headerlink" title="Permalink to this term" href="#TTYVTDisallocate="></a></dt><dd><p>If the terminal device specified with
<code class="varname">TTYPath=</code> 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
"<code class="literal">no</code>".</p></dd><dt id="SyslogIdentifier="><span class="term"><code class="varname">SyslogIdentifier=</code></span><a class="headerlink" title="Permalink to this term" href="#SyslogIdentifier="></a></dt><dd><p>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
<code class="varname">StandardOutput=</code> or
<code class="varname">StandardError=</code> are set to
<code class="option">syslog</code>, <code class="option">journal</code> or
<code class="option">kmsg</code> (or to the same settings in combination
with <code class="option">+console</code>).</p></dd><dt id="SyslogFacility="><span class="term"><code class="varname">SyslogFacility=</code></span><a class="headerlink" title="Permalink to this term" href="#SyslogFacility="></a></dt><dd><p>Sets the syslog facility to use when logging
to syslog. One of <code class="option">kern</code>,
<code class="option">user</code>, <code class="option">mail</code>,
<code class="option">daemon</code>, <code class="option">auth</code>,
<code class="option">syslog</code>, <code class="option">lpr</code>,
<code class="option">news</code>, <code class="option">uucp</code>,
<code class="option">cron</code>, <code class="option">authpriv</code>,
<code class="option">ftp</code>, <code class="option">local0</code>,
<code class="option">local1</code>, <code class="option">local2</code>,
<code class="option">local3</code>, <code class="option">local4</code>,
<code class="option">local5</code>, <code class="option">local6</code> or
<code class="option">local7</code>. See
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
for details. This option is only useful when
<code class="varname">StandardOutput=</code> or
<code class="varname">StandardError=</code> are set to
<code class="option">syslog</code>. Defaults to
<code class="option">daemon</code>.</p></dd><dt id="SyslogLevel="><span class="term"><code class="varname">SyslogLevel=</code></span><a class="headerlink" title="Permalink to this term" href="#SyslogLevel="></a></dt><dd><p>Default syslog level to use when logging to
syslog or the kernel log buffer. One of
<code class="option">emerg</code>,
<code class="option">alert</code>,
<code class="option">crit</code>,
<code class="option">err</code>,
<code class="option">warning</code>,
<code class="option">notice</code>,
<code class="option">info</code>,
<code class="option">debug</code>. See
<a href="http://man7.org/linux/man-pages/man3/syslog.3.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(3)</span></a>
for details. This option is only useful when
<code class="varname">StandardOutput=</code> or
<code class="varname">StandardError=</code> are set to
<code class="option">syslog</code> or <code class="option">kmsg</code>. 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 <code class="varname">SyslogLevelPrefix=</code>,
see below. For details see
<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>.
Defaults to
<code class="option">info</code>.</p></dd><dt id="SyslogLevelPrefix="><span class="term"><code class="varname">SyslogLevelPrefix=</code></span><a class="headerlink" title="Permalink to this term" href="#SyslogLevelPrefix="></a></dt><dd><p>Takes a boolean argument. If true and
<code class="varname">StandardOutput=</code> or
<code class="varname">StandardError=</code> are set to
<code class="option">syslog</code>, <code class="option">kmsg</code> or
<code class="option">journal</code>, 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
<a href="sd-daemon.html"><span class="citerefentry"><span class="refentrytitle">sd-daemon</span>(3)</span></a>.
Defaults to true.</p></dd><dt id="TimerSlackNSec="><span class="term"><code class="varname">TimerSlackNSec=</code></span><a class="headerlink" title="Permalink to this term" href="#TimerSlackNSec="></a></dt><dd><p>Sets the timer slack in nanoseconds for the
executed processes. The timer slack controls the accuracy of
wake-ups triggered by timers. See
<a href="http://man7.org/linux/man-pages/man2/prctl.2.html"><span class="citerefentry"><span class="refentrytitle">prctl</span>(2)</span></a>
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.</p></dd><dt id="LimitCPU="><span class="term"><code class="varname">LimitCPU=</code>, </span><span class="term"><code class="varname">LimitFSIZE=</code>, </span><span class="term"><code class="varname">LimitDATA=</code>, </span><span class="term"><code class="varname">LimitSTACK=</code>, </span><span class="term"><code class="varname">LimitCORE=</code>, </span><span class="term"><code class="varname">LimitRSS=</code>, </span><span class="term"><code class="varname">LimitNOFILE=</code>, </span><span class="term"><code class="varname">LimitAS=</code>, </span><span class="term"><code class="varname">LimitNPROC=</code>, </span><span class="term"><code class="varname">LimitMEMLOCK=</code>, </span><span class="term"><code class="varname">LimitLOCKS=</code>, </span><span class="term"><code class="varname">LimitSIGPENDING=</code>, </span><span class="term"><code class="varname">LimitMSGQUEUE=</code>, </span><span class="term"><code class="varname">LimitNICE=</code>, </span><span class="term"><code class="varname">LimitRTPRIO=</code>, </span><span class="term"><code class="varname">LimitRTTIME=</code></span><a class="headerlink" title="Permalink to this term" href="#LimitCPU="></a></dt><dd><p>These settings set both soft and hard limits
of various resources for executed processes. See
<a href="http://man7.org/linux/man-pages/man2/setrlimit.2.html"><span class="citerefentry"><span class="refentrytitle">setrlimit</span>(2)</span></a>
for details. Use the string <code class="varname">infinity</code> to
configure no limit on a specific resource.</p></dd><dt id="PAMName="><span class="term"><code class="varname">PAMName=</code></span><a class="headerlink" title="Permalink to this term" href="#PAMName="></a></dt><dd><p>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 <code class="varname">User=</code> setting. If
not set, no PAM session will be opened for the executed
processes. See
<a href="http://man7.org/linux/man-pages/man8/pam.8.html"><span class="citerefentry"><span class="refentrytitle">pam</span>(8)</span></a>
for details.</p></dd><dt id="CapabilityBoundingSet="><span class="term"><code class="varname">CapabilityBoundingSet=</code></span><a class="headerlink" title="Permalink to this term" href="#CapabilityBoundingSet="></a></dt><dd><p>Controls which capabilities to include in the
capability bounding set for the executed process. See
<a href="http://man7.org/linux/man-pages/man7/capabilities.7.html"><span class="citerefentry"><span class="refentrytitle">capabilities</span>(7)</span></a>
for details. Takes a whitespace-separated list of capability
names as read by
<a href="cap_from_name.html"><span class="citerefentry"><span class="refentrytitle">cap_from_name</span>(3)</span></a>,
e.g. <code class="constant">CAP_SYS_ADMIN</code>,
<code class="constant">CAP_DAC_OVERRIDE</code>,
<code class="constant">CAP_SYS_PTRACE</code>. Capabilities listed will
be included in the bounding set, all others are removed. If
the list of capabilities is prefixed with
"<code class="literal">~</code>", 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 <code class="varname">Capabilities=</code> 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 "<code class="literal">~</code>" (without any further argument),
the bounding set is reset to the full set of available
capabilities, also undoing any previous
settings.</p></dd><dt id="SecureBits="><span class="term"><code class="varname">SecureBits=</code></span><a class="headerlink" title="Permalink to this term" href="#SecureBits="></a></dt><dd><p>Controls the secure bits set for the executed
process. Takes a space-separated combination of options from
the following list:
<code class="option">keep-caps</code>,
<code class="option">keep-caps-locked</code>,
<code class="option">no-setuid-fixup</code>,
<code class="option">no-setuid-fixup-locked</code>,
<code class="option">noroot</code>, and
<code class="option">noroot-locked</code>.
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
<a href="http://man7.org/linux/man-pages/man7/capabilities.7.html"><span class="citerefentry"><span class="refentrytitle">capabilities</span>(7)</span></a>
for details.</p></dd><dt id="Capabilities="><span class="term"><code class="varname">Capabilities=</code></span><a class="headerlink" title="Permalink to this term" href="#Capabilities="></a></dt><dd><p>Controls the
<a href="http://man7.org/linux/man-pages/man7/capabilities.7.html"><span class="citerefentry"><span class="refentrytitle">capabilities</span>(7)</span></a>
set for the executed process. Take a capability string
describing the effective, permitted and inherited capability
sets as documented in
<a href="cap_from_text.html"><span class="citerefentry"><span class="refentrytitle">cap_from_text</span>(3)</span></a>.
Note that these capability sets are usually influenced (and
filtered) by the capabilities attached to the executed file.
Due to that <code class="varname">CapabilityBoundingSet=</code> is
probably a much more useful setting.</p></dd><dt id="ReadWriteDirectories="><span class="term"><code class="varname">ReadWriteDirectories=</code>, </span><span class="term"><code class="varname">ReadOnlyDirectories=</code>, </span><span class="term"><code class="varname">InaccessibleDirectories=</code></span><a class="headerlink" title="Permalink to this term" href="#ReadWriteDirectories="></a></dt><dd><p>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
<code class="varname">ReadWriteDirectories=</code> are accessible from
within the namespace with the same access rights as from
outside. Directories listed in
<code class="varname">ReadOnlyDirectories=</code> are accessible for
reading only, writing will be refused even if the usual file
access controls would permit this. Directories listed in
<code class="varname">InaccessibleDirectories=</code> 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.</p><p>Paths in
<code class="varname">ReadOnlyDirectories=</code>
and
<code class="varname">InaccessibleDirectories=</code>
may be prefixed with
"<code class="literal">-</code>", 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.</p></dd><dt id="PrivateTmp="><span class="term"><code class="varname">PrivateTmp=</code></span><a class="headerlink" title="Permalink to this term" href="#PrivateTmp="></a></dt><dd><p>Takes a boolean argument. If true, sets up a
new file system namespace for the executed processes and
mounts private <code class="filename">/tmp</code> and
<code class="filename">/var/tmp</code> 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 <code class="filename">/tmp</code>
or <code class="filename">/var/tmp</code> 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 <code class="filename">/tmp</code> and
<code class="filename">/var/tmp</code> namespace by using the
<code class="varname">JoinsNamespaceOf=</code> directive, see
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
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.</p></dd><dt id="PrivateDevices="><span class="term"><code class="varname">PrivateDevices=</code></span><a class="headerlink" title="Permalink to this term" href="#PrivateDevices="></a></dt><dd><p>Takes a boolean argument. If true, sets up a
new /dev namespace for the executed processes and only adds
API pseudo devices such as <code class="filename">/dev/null</code>,
<code class="filename">/dev/zero</code> or
<code class="filename">/dev/random</code> (as well as the pseudo TTY
subsystem) to it, but no physical devices such as
<code class="filename">/dev/sda</code>. This is useful to securely turn
off physical device access by the executed process. Defaults
to false. Enabling this option will also remove
<code class="constant">CAP_MKNOD</code> from the capability bounding
set for the unit (see above), and set
<code class="varname">DevicePolicy=closed</code> (see
<a href="systemd.resource-control.html"><span class="citerefentry"><span class="refentrytitle">systemd.resource-control</span>(5)</span></a>
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.</p></dd><dt id="PrivateNetwork="><span class="term"><code class="varname">PrivateNetwork=</code></span><a class="headerlink" title="Permalink to this term" href="#PrivateNetwork="></a></dt><dd><p>Takes a boolean argument. If true, sets up a
new network namespace for the executed processes and
configures only the loopback network device
"<code class="literal">lo</code>" 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
<code class="varname">JoinsNamespaceOf=</code> directive, see
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>
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).</p></dd><dt id="ProtectSystem="><span class="term"><code class="varname">ProtectSystem=</code></span><a class="headerlink" title="Permalink to this term" href="#ProtectSystem="></a></dt><dd><p>Takes a boolean argument or
"<code class="literal">full</code>". If true, mounts the
<code class="filename">/usr</code> and <code class="filename">/boot</code>
directories read-only for processes invoked by this unit. If
set to "<code class="literal">full</code>", the <code class="filename">/etc</code>
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 <code class="varname">CapabilityBoundingSet=</code>.
Defaults to off.</p></dd><dt id="ProtectHome="><span class="term"><code class="varname">ProtectHome=</code></span><a class="headerlink" title="Permalink to this term" href="#ProtectHome="></a></dt><dd><p>Takes a boolean argument or
"<code class="literal">read-only</code>". If true, the directories
<code class="filename">/home</code> and <code class="filename">/run/user</code>
are made inaccessible and empty for processes invoked by this
unit. If set to "<code class="literal">read-only</code>", 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 <code class="varname">CapabilityBoundingSet=</code>.
Defaults to off.</p></dd><dt id="MountFlags="><span class="term"><code class="varname">MountFlags=</code></span><a class="headerlink" title="Permalink to this term" href="#MountFlags="></a></dt><dd><p>Takes a mount propagation flag:
<code class="option">shared</code>, <code class="option">slave</code> or
<code class="option">private</code>, which control whether mounts in the
file system namespace set up for this unit's processes will
receive or propagate mounts or unmounts. See
<a href="http://man7.org/linux/man-pages/man2/mount.2.html"><span class="citerefentry"><span class="refentrytitle">mount</span>(2)</span></a>
for details. Defaults to <code class="option">shared</code>. Use
<code class="option">shared</code> to ensure that mounts and unmounts are
propagated from the host to the container and vice versa. Use
<code class="option">slave</code> to run processes so that none of their
mounts and unmounts will propagate to the host. Use
<code class="option">private</code> to also ensure that no mounts and
unmounts from the host will propagate into the unit processes'
namespace. Note that <code class="option">slave</code> 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
(<code class="varname">PrivateTmp=</code>,
<code class="varname">PrivateDevices=</code>,
<code class="varname">ProtectSystem=</code>,
<code class="varname">ProtectHome=</code>,
<code class="varname">ReadOnlyDirectories=</code>,
<code class="varname">InaccessibleDirectories=</code> and
<code class="varname">ReadWriteDirectories=</code>) require that mount
and unmount propagation from the unit's file system namespace
is disabled, and hence downgrade <code class="option">shared</code> to
<code class="option">slave</code>. </p></dd><dt id="UtmpIdentifier="><span class="term"><code class="varname">UtmpIdentifier=</code></span><a class="headerlink" title="Permalink to this term" href="#UtmpIdentifier="></a></dt><dd><p>Takes a four character identifier string for
an utmp/wtmp entry for this service. This should only be set
for services such as <span class="command"><strong>getty</strong></span> 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.</p></dd><dt id="SELinuxContext="><span class="term"><code class="varname">SELinuxContext=</code></span><a class="headerlink" title="Permalink to this term" href="#SELinuxContext="></a></dt><dd><p>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 "<code class="literal">-</code>", all errors
will be ignored. See
<a href="setexeccon.html"><span class="citerefentry"><span class="refentrytitle">setexeccon</span>(3)</span></a>
for details.</p></dd><dt id="AppArmorProfile="><span class="term"><code class="varname">AppArmorProfile=</code></span><a class="headerlink" title="Permalink to this term" href="#AppArmorProfile="></a></dt><dd><p>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 "<code class="literal">-</code>", all errors will
be ignored. </p></dd><dt id="SmackProcessLabel="><span class="term"><code class="varname">SmackProcessLabel=</code></span><a class="headerlink" title="Permalink to this term" href="#SmackProcessLabel="></a></dt><dd><p>Takes a <code class="option">SMACK64</code> 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 <code class="option">SMACK64EXEC</code> 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.</p><p>The value may be prefixed by "<code class="literal">-</code>", in
which case all errors will be ignored. An empty value may be
specified to unset previous assignments.</p></dd><dt id="IgnoreSIGPIPE="><span class="term"><code class="varname">IgnoreSIGPIPE=</code></span><a class="headerlink" title="Permalink to this term" href="#IgnoreSIGPIPE="></a></dt><dd><p>Takes a boolean argument. If true, causes
<code class="constant">SIGPIPE</code> to be ignored in the executed
process. Defaults to true because <code class="constant">SIGPIPE</code>
generally is useful only in shell pipelines.</p></dd><dt id="NoNewPrivileges="><span class="term"><code class="varname">NoNewPrivileges=</code></span><a class="headerlink" title="Permalink to this term" href="#NoNewPrivileges="></a></dt><dd><p>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.</p></dd><dt id="SystemCallFilter="><span class="term"><code class="varname">SystemCallFilter=</code></span><a class="headerlink" title="Permalink to this term" href="#SystemCallFilter="></a></dt><dd><p>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
<code class="constant">SIGSYS</code> signal (whitelisting). If the
first character of the list is "<code class="literal">~</code>", 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,
<code class="varname">NoNewPrivileges=yes</code> 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
<code class="function">execve</code>,
<code class="function">rt_sigreturn</code>,
<code class="function">sigreturn</code>,
<code class="function">exit_group</code>, <code class="function">exit</code>
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.</p><p>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
<code class="function">read</code> and <code class="function">write</code>, and
right after it add a blacklisting of
<code class="function">write</code>, then <code class="function">write</code>
will be removed from the set.) </p></dd><dt id="SystemCallErrorNumber="><span class="term"><code class="varname">SystemCallErrorNumber=</code></span><a class="headerlink" title="Permalink to this term" href="#SystemCallErrorNumber="></a></dt><dd><p>Takes an "<code class="literal">errno</code>" error number
name to return when the system call filter configured with
<code class="varname">SystemCallFilter=</code> is triggered, instead of
terminating the process immediately. Takes an error name such
as <code class="constant">EPERM</code>, <code class="constant">EACCES</code> or
<code class="constant">EUCLEAN</code>. When this setting is not used,
or when the empty string is assigned, the process will be
terminated immediately when the filter is
triggered.</p></dd><dt id="SystemCallArchitectures="><span class="term"><code class="varname">SystemCallArchitectures=</code></span><a class="headerlink" title="Permalink to this term" href="#SystemCallArchitectures="></a></dt><dd><p>Takes a space separated list of architecture
identifiers to include in the system call filter. The known
architecture identifiers are <code class="constant">x86</code>,
<code class="constant">x86-64</code>, <code class="constant">x32</code>,
<code class="constant">arm</code> as well as the special identifier
<code class="constant">native</code>. 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 <code class="constant">native</code> 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, <code class="varname">NoNewPrivileges=yes</code> is implied. Note
that setting this option to a non-empty list implies that
<code class="constant">native</code> is included too. By default, this
option is set to the empty list, i.e. no architecture system
call filtering is applied.</p></dd><dt id="RestrictAddressFamilies="><span class="term"><code class="varname">RestrictAddressFamilies=</code></span><a class="headerlink" title="Permalink to this term" href="#RestrictAddressFamilies="></a></dt><dd><p>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
<code class="constant">AF_UNIX</code>,
<code class="constant">AF_INET</code> or
<code class="constant">AF_INET6</code>. When
prefixed with <code class="constant">~</code> the listed address
families will be applied as blacklist, otherwise as whitelist.
Note that this restricts access to the
<a href="http://man7.org/linux/man-pages/man2/socket.2.html"><span class="citerefentry"><span class="refentrytitle">socket</span>(2)</span></a>
system call only. Sockets passed into the process by other
means (for example, by using socket activation with socket
units, see
<a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>)
are unaffected. Also, sockets created with
<code class="function">socketpair()</code> (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, <code class="varname">NoNewPrivileges=yes</code> 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.</p><p>Use this option to limit exposure of processes to remote
systems, in particular via exotic network protocols. Note that
in most cases, the local <code class="constant">AF_UNIX</code> address
family should be included in the configured whitelist as it is
frequently used for local communication, including for
<a href="http://man7.org/linux/man-pages/man2/syslog.2.html"><span class="citerefentry"><span class="refentrytitle">syslog</span>(2)</span></a>
logging.</p></dd><dt id="Personality="><span class="term"><code class="varname">Personality=</code></span><a class="headerlink" title="Permalink to this term" href="#Personality="></a></dt><dd><p>Controls which kernel architecture
<a href="http://man7.org/linux/man-pages/man2/uname.2.html"><span class="citerefentry"><span class="refentrytitle">uname</span>(2)</span></a>
shall report, when invoked by unit processes. Takes one of
<code class="constant">x86</code> and <code class="constant">x86-64</code>. 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.</p></dd><dt id="RuntimeDirectory="><span class="term"><code class="varname">RuntimeDirectory=</code>, </span><span class="term"><code class="varname">RuntimeDirectoryMode=</code></span><a class="headerlink" title="Permalink to this term" href="#RuntimeDirectory="></a></dt><dd><p>Takes a list of directory names. If set, one
or more directories by the specified names will be created
below <code class="filename">/run</code> (for system services) or below
<code class="varname">$XDG_RUNTIME_DIR</code> (for user services) when
the unit is started, and removed when the unit is stopped. The
directories will have the access mode specified in
<code class="varname">RuntimeDirectoryMode=</code>, and will be owned by
the user and group specified in <code class="varname">User=</code> and
<code class="varname">Group=</code>. Use this to manage one or more
runtime directories of the unit and bind their lifetime to the
daemon runtime. The specified directory names must be
relative, and may not include a "<code class="literal">/</code>", i.e.
must refer to simple directories to create or remove. This is
particularly useful for unprivileged daemons that cannot
create runtime directories in <code class="filename">/run</code> due to
lack of privileges, and to make sure the runtime directory is
cleaned up automatically after use. For runtime directories
that require more complex or different configuration or
lifetime guarantees, please consider using
<a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a>.</p></dd></dl></div></div><div class="refsect1"><a name="idm140278902375200"></a><h2 id="Environment variables in spawned processes">Environment variables in spawned processes<a class="headerlink" title="Permalink to this headline" href="#Environment%20variables%20in%20spawned%20processes"></a></h2><p>Processes started by the system are executed in a clean
environment in which select variables listed below are set. System
processes started by systemd do not inherit variables from PID 1,
but processes started by user systemd instances inherit all
environment variables from the user systemd instance.
</p><div class="variablelist"><dl class="variablelist"><dt id="$PATH"><span class="term"><code class="varname">$PATH</code></span><a class="headerlink" title="Permalink to this term" href="#%24PATH"></a></dt><dd><p>Colon-separated list of directories to use
when launching executables. Systemd uses a fixed value of
<code class="filename">/usr/local/sbin</code>:<code class="filename">/usr/local/bin</code>:<code class="filename">/usr/sbin</code>:<code class="filename">/usr/bin</code>:<code class="filename">/sbin</code>:<code class="filename">/bin</code>.
</p></dd><dt id="$LANG"><span class="term"><code class="varname">$LANG</code></span><a class="headerlink" title="Permalink to this term" href="#%24LANG"></a></dt><dd><p>Locale. Can be set in
<a href="locale.conf.html"><span class="citerefentry"><span class="refentrytitle">locale.conf</span>(5)</span></a>
or on the kernel command line (see
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>
and
<a href="kernel-command-line.html"><span class="citerefentry"><span class="refentrytitle">kernel-command-line</span>(7)</span></a>).
</p></dd><dt id="$USER"><span class="term"><code class="varname">$USER</code>, </span><span class="term"><code class="varname">$LOGNAME</code>, </span><span class="term"><code class="varname">$HOME</code>, </span><span class="term"><code class="varname">$SHELL</code></span><a class="headerlink" title="Permalink to this term" href="#%24USER"></a></dt><dd><p>User name (twice), home directory, and the
login shell. The variables are set for the units that have
<code class="varname">User=</code> set, which includes user
<span class="command"><strong>systemd</strong></span> instances. See
<a href="passwd.html"><span class="citerefentry"><span class="refentrytitle">passwd</span>(5)</span></a>.
</p></dd><dt id="$XDG_RUNTIME_DIR"><span class="term"><code class="varname">$XDG_RUNTIME_DIR</code></span><a class="headerlink" title="Permalink to this term" href="#%24XDG_RUNTIME_DIR"></a></dt><dd><p>The directory for volatile state. Set for the
user <span class="command"><strong>systemd</strong></span> instance, and also in user
sessions. See
<a href="pam_systemd.html"><span class="citerefentry"><span class="refentrytitle">pam_systemd</span>(8)</span></a>.
</p></dd><dt id="$XDG_SESSION_ID"><span class="term"><code class="varname">$XDG_SESSION_ID</code>, </span><span class="term"><code class="varname">$XDG_SEAT</code>, </span><span class="term"><code class="varname">$XDG_VTNR</code></span><a class="headerlink" title="Permalink to this term" href="#%24XDG_SESSION_ID"></a></dt><dd><p>The identifier of the session, the seat name,
and virtual terminal of the session. Set by
<a href="pam_systemd.html"><span class="citerefentry"><span class="refentrytitle">pam_systemd</span>(8)</span></a>
for login sessions. <code class="varname">$XDG_SEAT</code> and
<code class="varname">$XDG_VTNR</code> will only be set when attached to
a seat and a tty.</p></dd><dt id="$MAINPID"><span class="term"><code class="varname">$MAINPID</code></span><a class="headerlink" title="Permalink to this term" href="#%24MAINPID"></a></dt><dd><p>The PID of the units main process if it is
known. This is only set for control processes as invoked by
<code class="varname">ExecReload=</code> and similar. </p></dd><dt id="$MANAGERPID"><span class="term"><code class="varname">$MANAGERPID</code></span><a class="headerlink" title="Permalink to this term" href="#%24MANAGERPID"></a></dt><dd><p>The PID of the user <span class="command"><strong>systemd</strong></span>
instance, set for processes spawned by it. </p></dd><dt id="$LISTEN_FDS"><span class="term"><code class="varname">$LISTEN_FDS</code>, </span><span class="term"><code class="varname">$LISTEN_PID</code></span><a class="headerlink" title="Permalink to this term" href="#%24LISTEN_FDS"></a></dt><dd><p>Information about file descriptors passed to a
service for socket activation. See
<a href="sd_listen_fds.html"><span class="citerefentry"><span class="refentrytitle">sd_listen_fds</span>(3)</span></a>.
</p></dd><dt id="$TERM"><span class="term"><code class="varname">$TERM</code></span><a class="headerlink" title="Permalink to this term" href="#%24TERM"></a></dt><dd><p>Terminal type, set only for units connected to
a terminal (<code class="varname">StandardInput=tty</code>,
<code class="varname">StandardOutput=tty</code>, or
<code class="varname">StandardError=tty</code>). See
<a href="http://man7.org/linux/man-pages/man5/termcap.5.html"><span class="citerefentry"><span class="refentrytitle">termcap</span>(5)</span></a>.
</p></dd></dl></div><p>Additional variables may be configured by the following
means: for processes spawned in specific units, use the
<code class="varname">Environment=</code> and
<code class="varname">EnvironmentFile=</code> options above; to specify
variables globally, use <code class="varname">DefaultEnvironment=</code>
(see
<a href="systemd-system.conf.html"><span class="citerefentry"><span class="refentrytitle">systemd-system.conf</span>(5)</span></a>)
or the kernel option <code class="varname">systemd.setenv=</code> (see
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>).
Additional variables may also be set through PAM,
cf. <a href="http://man7.org/linux/man-pages/man8/pam_env.8.html"><span class="citerefentry"><span class="refentrytitle">pam_env</span>(8)</span></a>.</p></div><div class="refsect1"><a name="idm140278902336960"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also"></a></h2><p>
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
<a href="systemctl.html"><span class="citerefentry"><span class="refentrytitle">systemctl</span>(1)</span></a>,
<a href="journalctl.html"><span class="citerefentry"><span class="refentrytitle">journalctl</span>(8)</span></a>,
<a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>,
<a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
<a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>,
<a href="systemd.swap.html"><span class="citerefentry"><span class="refentrytitle">systemd.swap</span>(5)</span></a>,
<a href="systemd.mount.html"><span class="citerefentry"><span class="refentrytitle">systemd.mount</span>(5)</span></a>,
<a href="systemd.kill.html"><span class="citerefentry"><span class="refentrytitle">systemd.kill</span>(5)</span></a>,
<a href="systemd.resource-control.html"><span class="citerefentry"><span class="refentrytitle">systemd.resource-control</span>(5)</span></a>,
<a href="systemd.directives.html"><span class="citerefentry"><span class="refentrytitle">systemd.directives</span>(7)</span></a>,
<a href="tmpfiles.d.html"><span class="citerefentry"><span class="refentrytitle">tmpfiles.d</span>(5)</span></a>,
<a href="http://man7.org/linux/man-pages/man3/exec.3.html"><span class="citerefentry"><span class="refentrytitle">exec</span>(3)</span></a>
</p></div></div></body></html>
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