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systemd-stable/man/systemd.exec.xml
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<refentry id="systemd.exec">
<refentryinfo>
<title>systemd.exec</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.exec</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.exec</refname>
<refpurpose>systemd execution environment configuration</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>systemd.service</filename>,
<filename>systemd.socket</filename>,
<filename>systemd.mount</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>Unit configuration files for services, sockets
and mount points 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 three 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>
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] resp. [Mount] section, depending on the unit
type.</para>
</refsect1>
<refsect1>
<title>Options</title>
<variablelist>
<varlistentry>
<term><varname>WorkingDirectory=</varname></term>
<listitem><para>Takes an absolute
directory path. Sets the working
directory for executed
processes.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>RootDirectory=</varname></term>
<listitem><para>Takes an absolute
directory path. Sets the root
directory for executed processes, with
the
<citerefentry><refentrytitle>chroot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
system call. If this is used it must
be ensured that the process and all
its auxiliary files are available in
the <function>chroot()</function>
jail.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>User=</varname></term>
<term><varname>Group=</varname></term>
<listitem><para>Sets the Unix user
resp. group the processes are executed
as. Takes a single user resp. group
name or ID as argument. If no group is
set the default group of the user is
chosen.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SupplementaryGroups=</varname></term>
<listitem><para>Sets the supplementary
Unix groups the processes are executed
as. This takes a space separated list
of group names or IDs. This option may
be specified more than once in which
case all listed groups are set as
supplementary groups. This option does
not override but extends the list of
supplementary groups configured in the
system group database for the
user.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Nice=</varname></term>
<listitem><para>Sets the default nice
level (scheduling priority) for
executed processes. Takes an integer
between -20 (highest priority) and 19
(lowest priority). See
<citerefentry><refentrytitle>setpriority</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>OOMScoreAdjust=</varname></term>
<listitem><para>Sets the adjustment
level for the Out-Of-Memory killer for
executed processes. Takes an integer
between -1000 (to disable OOM killing
for this process) and 1000 (to make
killing of this process under memory
pressure very likely). See <ulink
url="http://www.kernel.org/doc/Documentation/filesystems/proc.txt">proc.txt</ulink>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>IOSchedulingClass=</varname></term>
<listitem><para>Sets the IO scheduling
class for executed processes. Takes an
integer between 0 and 3 or one of the
strings <option>none</option>,
<option>realtime</option>,
<option>best-effort</option> or
<option>idle</option>. See
<citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>IOSchedulingPriority=</varname></term>
<listitem><para>Sets the IO scheduling
priority for executed processes. Takes
an integer between 0 (highest
priority) and 7 (lowest priority). The
available priorities depend on the
selected IO scheduling class (see
above). See
<citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUSchedulingPolicy=</varname></term>
<listitem><para>Sets the CPU
scheduling policy for executed
processes. Takes one of
<option>other</option>,
<option>batch</option>,
<option>idle</option>,
<option>fifo</option> or
<option>rr</option>. See
<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUSchedulingPriority=</varname></term>
<listitem><para>Sets the CPU
scheduling priority for executed
processes. Takes an integer between 1
(lowest priority) and 99 (highest
priority). The available priority
range depends on the selected CPU
scheduling policy (see above). See
<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUSchedulingResetOnFork=</varname></term>
<listitem><para>Takes a boolean
argument. If true elevated CPU
scheduling priorities and policies
will be reset when the executed
processes fork, and can hence not leak
into child processes. See
<citerefentry><refentrytitle>sched_setscheduler</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details. Defaults to false.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CPUAffinity=</varname></term>
<listitem><para>Controls the CPU
affinity of the executed
processes. Takes a space-separated
list of CPU indexes. See
<citerefentry><refentrytitle>sched_setaffinity</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>UMask=</varname></term>
<listitem><para>Controls the file mode
creation mask. Takes an access mode in
octal notation. See
<citerefentry><refentrytitle>umask</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details. Defaults to
0002.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Environment=</varname></term>
<listitem><para>Sets environment
variables for executed
processes. Takes a space-separated
list of variable assignments. This
option may be specified more than once
in which case all listed variables
will be set. If the same variable is
set twice the later setting will
override the earlier setting. See
<citerefentry><refentrytitle>environ</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>EnvironmentFile=</varname></term>
<listitem><para>Similar to
<varname>Environment=</varname> but
reads the environment variables from a
text file. The text file should
contain new-line separated variable
assignments. Empty lines and lines
starting with ; or # will be ignored,
which may be used for
commenting.</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> 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 logger. <option>kmsg</option>
connects it with the kernel log buffer
which is accessible via
<citerefentry><refentrytitle>dmesg</refentrytitle><manvolnum>1</manvolnum></citerefentry>. <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
<option>inherit</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>,
whith one exception: if set to
<option>inherit</option> the file
descriptor used for standard output is
duplicated for standard error. This
setting defaults to
<option>inherit</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>TTYPath=</varname></term>
<listitem><para>Sets the terminal
device node to use if standard input,
output or stderr are connected to a
TTY (see above). Defaults to
<filename>/dev/console</filename>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SyslogIdentifer=</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>7</manvolnum></citerefentry>.
Defaults to
<option>info</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>SyslogLevelPrefix=</varname></term>
<listitem><para>Takes a boolean
argument. If true and
<varname>StandardOutput=</varname> or
<varname>StandardError=</varname> are
set to <option>syslog</option> or
<option>kmsg</option> log lines
written by the executed process that
are prefixed with a log level will be
passed on to syslog with this log
level set but the prefix removed. If
set to false, the interpretation of
these prefixes is disabled and the
logged lines are passed on as-is. For
details about this prefixing see
<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</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 and does
not understand any other
units.</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.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PAMName=</varname></term>
<listitem><para>Sets the PAM service
name to set up a session as. If set
the executed process will be
registered as a PAM session under the
specified service name. This is only
useful in conjunction with the
<varname>User=</varname> setting. If
not set no PAM session will be opened
for the executed processes. See
<citerefentry><refentrytitle>pam</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>TCPWrapName=</varname></term>
<listitem><para>If this is a
socket-activated service this sets the
tcpwrap service name to check the
permission for the current connection
with. This is only useful in
conjunction with socket-activated
services, and stream sockets (TCP) in
particular. It has no effect on other
socket types (e.g. datagram/UDP) and on processes
unrelated to socket-based
activation. If the tcpwrap
verification fails daemon start-up
will fail and the connection is
terminated. See
<citerefentry><refentrytitle>tcpd</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for details.</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 as described in
<citerefentry><refentrytitle>cap_from_text</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
Note that this capability set is
usually influenced by the capabilities
attached to the executed
file.</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>no-setuid-noroot</option> and/or
<option>no-setuid-noroot-locked</option>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>CapabilityBoundingSetDrop=</varname></term>
<listitem><para>Controls the
capability bounding set drop set for
the executed process. See
<citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details. Takes a list of
capability names as read by
<citerefentry><refentrytitle>cap_from_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</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 hierachies -- 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. 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>ReadWriteDirectories=</varname></term>
<term><varname>ReadOnlyDirectories=</varname></term>
<term><varname>InaccessibleDirectories=</varname></term>
<listitem><para>Sets up a new
file-system name space for executed
processes. These options may be used
to limit access a process might have
to the main file-system
hierarchy. Each setting takes a
space-separated list of absolute
directory paths. Directories listed in
<varname>ReadWriteDirectories=</varname>
are accessible from within the
namespace with the same access rights
as from outside. Directories listed in
<varname>ReadOnlyDirectories=</varname>
are accessible for reading only,
writing will be refused even if the
usual file access controls would
permit this. Directories listed in
<varname>InaccessibleDirectories=</varname>
will be made inaccesible 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 setttings to
ensure the same limited access. These
options may be specified more than
once in which case all directories
listed will have limited access from
within the
namespace.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>PrivateTmp=</varname></term>
<listitem><para>Takes a boolean
argument. If true sets up a new
namespace for the executed processes
and mounts a private
<filename>/tmp</filename> directory
inside it, that is not shared by
processes outside of the
namespace. This is useful to secure
access to temporary files of the
process, but makes sharing between
processes via
<filename>/tmp</filename>
impossible. Defaults to false.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>MountFlags=</varname></term>
<listitem><para>Takes a mount
propagation flag:
<option>shared</option>,
<option>slave</option> or
<option>private</option>, which
control whether namespaces set up with
<varname>ReadWriteDirectories=</varname>,
<varname>ReadOnlyDirectories=</varname>
and
<varname>InaccessibleDirectories=</varname>
receive or propagate new mounts
from/to the main namespace. See
<citerefentry><refentrytitle>mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>
for details. Defaults to
<option>shared</option>, i.e. the new
namespace will both receive new mount
points from the main namespace as well
as propagate new mounts to
it.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>UtmpIdentifier=</varname></term>
<listitem><para>Takes a a four
character identifier string for an
utmp/wtmp entry for this service. This
should only be set for services such
as <command>getty</command>
implementations where utmp/wtmp
entries must be created and cleared
before and after execution. If the
configured string is longer than four
characters it is truncated and the
terminal four characters are
used. This setting interprets %I style
string replacements. This setting is
unset by default, i.e. no utmp/wtmp
entries are created or cleaned up for
this service.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>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.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>