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<refsynopsisdiv>
- <para><filename>systemd.service</filename>,
- <filename>systemd.socket</filename>,
- <filename>systemd.mount</filename>,
- <filename>systemd.swap</filename></para>
+ <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
+ mount points, and swap devices share a subset of
configuration options which define the execution
environment of spawned processes.</para>
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>
+ <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
and
<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for more information on the specific unit
configuration files. The execution specific
configuration options are configured in the [Service],
- [Socket], [Mount] resp. [Swap] section, depending on the unit
+ [Socket], [Mount], or [Swap] sections, depending on the unit
type.</para>
</refsect1>
<refsect1>
<title>Options</title>
- <variablelist>
+ <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
+ 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
directory for executed processes, with
the
<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- system call. If this is used it must
+ 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>
<term><varname>Group=</varname></term>
<listitem><para>Sets the Unix user
- resp. group the processes are executed
- as. Takes a single user resp. group
+ 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
+ set, the default group of the user is
chosen.</para></listitem>
</varlistentry>
<listitem><para>Sets the supplementary
Unix groups the processes are executed
- as. This takes a space separated list
+ as. This takes a space-separated list
of group names or IDs. This option may
be specified more than once in which
case all listed groups are set as
- supplementary groups. This option does
- not override but extends the list of
- supplementary groups configured in the
- system group database for the
+ 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>
for this process) and 1000 (to make
killing of this process under memory
pressure very likely). See <ulink
- url="http://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
+ url="https://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
for details.</para></listitem>
</varlistentry>
<listitem><para>Sets the CPU
scheduling priority for executed
- processes. Takes an integer between 1
- (lowest priority) and 99 (highest
- priority). The available priority
+ processes. The available priority
range depends on the selected CPU
- scheduling policy (see above). See
- <citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
- for details.</para></listitem>
+ 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
+ argument. If true, elevated CPU
scheduling priorities and policies
will be reset when the executed
processes fork, and can hence not leak
<listitem><para>Controls the CPU
affinity of the executed
processes. Takes a space-separated
- list of CPU indexes. See
+ 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>
option may be specified more than once
in which case all listed variables
will be set. If the same variable is
- set twice the later setting will
- override the earlier setting. See
+ 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.</para></listitem>
+ for details about environment variables.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>EnvironmentFile=</varname></term>
<varname>Environment=</varname> but
reads the environment variables from a
text file. The text file should
- contain new-line separated variable
+ contain new-line-separated variable
assignments. Empty lines and lines
starting with ; or # will be ignored,
- which may be used for commenting. The
- parser strips leading and
- trailing whitespace from the values
+ 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 (").
- The
- argument passed should be an absolute
- file name, optionally prefixed with
- "-", which indicates that if the file
- does not exist it won't be read and no
- error or warning message is
- logged. The files listed with this
+ 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. 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
+ these files, the files will be read in
the order they are specified and the
later setting will override the
- earlier setting. </para></listitem>
+ earlier setting.</para></listitem>
</varlistentry>
<varlistentry>
<option>tty-force</option>,
<option>tty-fail</option> or
<option>socket</option>. If
- <option>null</option> is selected
+ <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
+ <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
+ being controlled by another process, the
executed process waits until the current
controlling process releases the
terminal.
file (see
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) specifies a single socket
- only. If this option is set standard
+ 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
<option>kmsg+console</option>,
<option>journal+console</option> or
<option>socket</option>. If set to
- <option>inherit</option> the file
+ <option>inherit</option>, the file
descriptor of standard input is
duplicated for standard output. If set
- to <option>null</option> standard
+ 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>
+ 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
+ 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
with
<option>DefaultStandardOutput=</option>
in
- <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <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
+ descriptor 2 (standard error) of the
+ executed processes is connected to.
+ The available options are identical to
those of
<varname>StandardOutput=</varname>,
with one exception: if set to
setting defaults to the value set with
<option>DefaultStandardError=</option>
in
- <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <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 stderr are connected to a
+ 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>
<varlistentry>
<term><varname>TTYVTDisallocate=</varname></term>
- <listitem><para>If the the terminal
+ <listitem><para>If the terminal
device specified with
<varname>TTYPath=</varname> is a
- virtual console terminal try to
+ virtual console terminal, try to
deallocate the TTY before and after
execution. This ensures that the
screen and scrollback buffer is
<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
+ the kernel log buffer with. If not set,
defaults to the process name of the
executed process. This option is only
useful when
argument. If true and
<varname>StandardOutput=</varname> or
<varname>StandardError=</varname> are
- set to <option>syslog</option> or
- <option>kmsg</option> log lines
+ 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
<varlistentry>
<term><varname>PAMName=</varname></term>
<listitem><para>Sets the PAM service
- name to set up a session as. If set
+ 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
+ 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>
<term><varname>TCPWrapName=</varname></term>
<listitem><para>If this is a
- socket-activated service this sets the
+ socket-activated service, this sets the
tcpwrap service name to check the
permission for the current connection
with. This is only useful in
socket types (e.g. datagram/UDP) and
on processes unrelated to socket-based
activation. If the tcpwrap
- verification fails daemon start-up
+ verification fails, daemon start-up
will fail and the connection is
terminated. See
<citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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>.
+ 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 ~ all but the listed
- capabilities will be included, the
- effect of the assignment
- inverted. Note that this option also
- effects the respective capabilities in
- the effective, permitted and
- inheritable capability sets, on top of
- what <varname>Capabilities=</varname>
- does. If this option is not used the
+ 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.</para></listitem>
+ 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>
<option>no-setuid-fixup</option>,
<option>no-setuid-fixup-locked</option>,
<option>noroot</option> and/or
- <option>noroot-locked</option>.
- </para></listitem>
+ <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>
setting.</para></listitem>
</varlistentry>
- <varlistentry>
- <term><varname>ControlGroup=</varname></term>
-
- <listitem><para>Controls the control
- groups the executed processes shall be
- made members of. Takes a
- space-separated list of cgroup
- identifiers. A cgroup identifier has a
- format like
- <filename>cpu:/foo/bar</filename>,
- where "cpu" identifies the kernel
- control group controller used, and
- <filename>/foo/bar</filename> is the
- control group path. The controller
- name and ":" may be omitted in which
- case the named systemd control group
- hierarchy is implied. Alternatively,
- the path and ":" may be omitted, in
- which case the default control group
- path for this unit is implied. This
- option may be used to place executed
- processes in arbitrary groups in
- arbitrary hierarchies -- which can be
- configured externally with additional
- execution limits. By default systemd
- will place all executed processes in
- separate per-unit control groups
- (named after the unit) in the systemd
- named hierarchy. Since every process
- can be in one group per hierarchy only
- overriding the control group path in
- the named systemd hierarchy will
- disable automatic placement in the
- default group. This option is
- primarily intended to place executed
- processes in specific paths in
- specific kernel controller
- hierarchies. It is however not
- recommended to manipulate the service
- control group path in the systemd
- named hierarchy. For details about
- control groups see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupModify=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, the control groups
- created for this unit will be owned by
- the user specified with
- <varname>User=</varname> (and the
- appropriate group), and he/she can create
- subgroups as well as add processes to
- the group.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupPersistent=</varname></term>
- <listitem><para>Takes a boolean
- argument. If true, the control groups
- created for this unit will be marked
- to be persistent, i.e. systemd will
- not remove them when stopping the
- unit. The default is false, meaning
- that the control groups will be
- removed when the unit is stopped. For
- details about the semantics of this
- logic see <ulink
- url="http://www.freedesktop.org/wiki/Software/systemd/PaxControlGroups">PaxControlGroups</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>ControlGroupAttribute=</varname></term>
-
- <listitem><para>Set a specific control
- group attribute for executed
- processes, and (if needed) add the the
- executed processes to a cgroup in the
- hierarchy of the controller the
- attribute belongs to. Takes two
- space-separated arguments: the
- attribute name (syntax is
- <literal>cpu.shares</literal> where
- <literal>cpu</literal> refers to a
- specific controller and
- <literal>shares</literal> to the
- attribute name), and the attribute
- value. Example:
- <literal>ControlGroupAttribute=cpu.shares
- 512</literal>. If this option is used
- for an attribute that belongs to a
- kernel controller hierarchy the unit
- is not already configured to be added
- to (for example via the
- <literal>ControlGroup=</literal>
- option) then the unit will be added to
- the controller and the default unit
- cgroup path is implied. Thus, using
- <varname>ControlGroupAttribute=</varname>
- is in most case sufficient to make use
- of control group enforcements,
- explicit
- <varname>ControlGroup=</varname> are
- only necessary in case the implied
- default control group path for a
- service is not desirable. For details
- about control group attributes see
- <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>. This
- option may appear more than once, in
- order to set multiple control group
- attributes.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>CPUShares=</varname></term>
-
- <listitem><para>Assign the specified
- overall CPU time shares to the
- processes executed. Takes an integer
- value. This controls the
- <literal>cpu.shares</literal> control
- group attribute, which defaults to
- 1024. For details about this control
- group attribute see <ulink
- url="http://www.kernel.org/doc/Documentation/scheduler/sched-design-CFS.txt">sched-design-CFS.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>MemoryLimit=</varname></term>
- <term><varname>MemorySoftLimit=</varname></term>
-
- <listitem><para>Limit the overall memory usage
- of the executed processes to a certain
- size. Takes a memory size in bytes. If
- the value is suffixed with K, M, G or
- T the specified memory size is parsed
- as Kilobytes, Megabytes, Gigabytes,
- resp. Terabytes (to the base
- 1024). This controls the
- <literal>memory.limit_in_bytes</literal>
- and
- <literal>memory.soft_limit_in_bytes</literal>
- control group attributes. For details
- about these control group attributes
- see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/memory.txt">memory.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>DeviceAllow=</varname></term>
- <term><varname>DeviceDeny=</varname></term>
-
- <listitem><para>Control access to
- specific device nodes by the executed processes. Takes two
- space separated strings: a device node
- path (such as
- <filename>/dev/null</filename>)
- followed by a combination of r, w, m
- to control reading, writing resp.
- creating of the specific device node
- by the unit. This controls the
- <literal>devices.allow</literal>
- and
- <literal>devices.deny</literal>
- control group attributes. For details
- about these control group attributes
- see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/devices.txt">devices.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BlockIOWeight=</varname></term>
-
- <listitem><para>Set the default or
- per-device overall block IO weight
- value for the executed
- processes. Takes either a single
- weight value (between 10 and 1000) to
- set the default block IO weight, or a
- space separated pair of a file path
- and a weight value to specify the
- device specific weight value (Example:
- "/dev/sda 500"). The file path may be
- specified as path to a block device
- node or as any other file in which
- case the backing block device of the
- file system of the file is
- determined. This controls the
- <literal>blkio.weight</literal> and
- <literal>blkio.weight_device</literal>
- control group attributes, which
- default to 1000. Use this option
- multiple times to set weights for
- multiple devices. For details about
- these control group attributes see
- <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para></listitem>
- </varlistentry>
-
- <varlistentry>
- <term><varname>BlockIOReadBandwidth=</varname></term>
- <term><varname>BlockIOWriteBandwidth=</varname></term>
-
- <listitem><para>Set the per-device
- overall block IO bandwidth limit for
- the executed processes. Takes a space
- separated pair of a file path and a
- bandwidth value (in bytes per second)
- to specify the device specific
- bandwidth. The file path may be
- specified as path to a block device
- node or as any other file in which
- case the backing block device of the
- file system of the file is determined.
- If the bandwidth is suffixed with K, M,
- G, or T the specified bandwidth is
- parsed as Kilobytes, Megabytes,
- Gigabytes, resp. Terabytes (Example:
- "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0
- 5M"). This controls the
- <literal>blkio.read_bps_device</literal>
- and
- <literal>blkio.write_bps_device</literal>
- control group attributes. Use this
- option multiple times to set bandwidth
- limits for multiple devices. For
- details about these control group
- attributes see <ulink
- url="http://www.kernel.org/doc/Documentation/cgroups/blkio-controller.txt">blkio-controller.txt</ulink>.</para></listitem>
- </varlistentry>
-
<varlistentry>
<term><varname>ReadWriteDirectories=</varname></term>
<term><varname>ReadOnlyDirectories=</varname></term>
<term><varname>InaccessibleDirectories=</varname></term>
<listitem><para>Sets up a new
- file-system name space for executed
+ file system namespace for executed
processes. These options may be used
to limit access a process might have
- to the main file-system
+ to the main file system
hierarchy. Each setting takes a
space-separated list of absolute
directory paths. Directories listed in
usual file access controls would
permit this. Directories listed in
<varname>InaccessibleDirectories=</varname>
- will be made inaccessible for processes
- inside the namespace. Note that
- restricting access with these options
- does not extend to submounts of a
- directory. You must list submounts
- separately in these settings to
- ensure the same limited access. These
- options may be specified more than
- once in which case all directories
- listed will have limited access from
- within the
- namespace.</para></listitem>
+ will be made inaccessible for
+ processes inside the namespace. Note
+ that restricting access with these
+ options does not extend to submounts
+ of a directory. You must list
+ submounts separately in these settings
+ to ensure the same limited
+ access. These options may be specified
+ more than once in which case all
+ directories listed will have limited
+ access from within the namespace. 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.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PrivateTmp=</varname></term>
<listitem><para>Takes a boolean
- argument. If true sets up a new file
+ argument. If true, sets up a new file
system namespace for the executed
- processes and mounts a private
- <filename>/tmp</filename> directory
- inside it, that is not shared by
- processes outside of the
+ 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>
- impossible. Defaults to
- false.</para></listitem>
+ <filename>/tmp</filename> or
+ <filename>/var/tmp</filename>
+ impossible. All temporary data created
+ by service will be removed after
+ the service is stopped. Defaults to
+ false. Note that 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.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PrivateNetwork=</varname></term>
<listitem><para>Takes a boolean
- argument. If true sets up a new
+ argument. If true, sets up a new
network namespace for the executed
processes and configures only the
loopback network device
available to the executed process.
This is useful to securely turn off
network access by the executed
+ process. Defaults to false. Note that
+ 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.</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> 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.</para></listitem>
</varlistentry>
namespace set up for this unit's
processes will receive or propagate
new mounts. See
- <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>mount</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details. Default to
<option>shared</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>UtmpIdentifier=</varname></term>
- <listitem><para>Takes a a four
+ <listitem><para>Takes a four
character identifier string for an
utmp/wtmp entry for this service. This
should only be set for services such
entries must be created and cleared
before and after execution. If the
configured string is longer than four
- characters it is truncated and the
+ characters, it is truncated and the
terminal four characters are
used. This setting interprets %I style
string replacements. This setting is
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>IgnoreSIGPIPE=</varname></term>
<listitem><para>Takes a boolean
- argument. If true causes SIGPIPE to be
+ argument. If true, causes <constant>SIGPIPE</constant> to be
ignored in the executed
- process. Defaults to true, since
- SIGPIPE generally is useful only in
+ process. Defaults to true because
+ <constant>SIGPIPE</constant> generally is useful only in
shell pipelines.</para></listitem>
</varlistentry>
<term><varname>NoNewPrivileges=</varname></term>
<listitem><para>Takes a boolean
- argument. If true ensures that the
+ 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
<varlistentry>
<term><varname>SystemCallFilter=</varname></term>
- <listitem><para>Takes a space
- separated list of system call
- names. If this setting is used all
+ <listitem><para>Takes a space-separated
+ list of system call
+ names. If this setting is used, all
system calls executed by the unit
- process except for the listed ones
+ processes except for the listed ones
will result in immediate process
- termination with the SIGSYS signal
+ termination with the
+ <constant>SIGSYS</constant> signal
(whitelisting). If the first character
- of the list is <literal>~</literal>
+ of the list is <literal>~</literal>,
the effect is inverted: only the
listed system calls will result in
immediate process termination
- (blacklisting). If this option is used
+ (blacklisting). If this option is used,
<varname>NoNewPrivileges=yes</varname>
is implied. This feature makes use of
the Secure Computing Mode 2 interfaces
<function>sigreturn</function>,
<function>exit_group</function>,
<function>exit</function> system calls
- are implicitly whitelisted and don't
- need to be listed
- explicitly.</para></listitem>
+ 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
+ <literal>EPERM</literal>,
+ <literal>EACCES</literal> or
+ <literal>EUCLEAN</literal>. 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
+ <literal>x86</literal>,
+ <literal>x86-64</literal>,
+ <literal>x32</literal>,
+ <literal>arm</literal> as well as the
+ special identifier
+ <literal>native</literal>. 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
+ <literal>native</literal> identifier
+ implicitly maps to the native
+ architecture of the system (or more
+ strictly: to the architecture the
+ system manager is compiled for). Note
+ that setting this option to a
+ non-empty list implies that
+ <literal>native</literal> 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>
+
+ </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>$MANAGERPID</varname></term>
+
+ <listitem><para>The PID of the user
+ <command>systemd</command> instance,
+ set for processes spawned by it.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>$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,
+ c.f. <citerefentry><refentrytitle>pam_env</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
</refsect1>
<refsect1>
<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.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>exec</refentrytitle><manvolnum>3</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff