| <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?> |
| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
| "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| |
| <!-- |
| This file is part of systemd. |
| |
| Copyright 2010 Lennart Poettering |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| --> |
| |
| <refentry id="systemd.exec"> |
| <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><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 specificed 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><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>. 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-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 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>, |
| <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 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>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>, |
| 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. 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>. 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.</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 (and filtered) 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>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> |
| directory 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 directores 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 continously 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>ReadOnlySystem=</varname>, |
| <varname>ProtectedHome=</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 autorize 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>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 directiories 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><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><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>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>, |
| <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><refentrytitle>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |