OPTIONS¶
WorkingDirectory=
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.
RootDirectory=
Takes an absolute directory path. Sets the root directory
for executed processes, with the
chroot(2) system call. If this is
used, it must be ensured that the process and all its auxiliary files are
available in the
chroot() jail.
User=, Group=
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.
SupplementaryGroups=
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.
Nice=
Sets the default nice level (scheduling priority) for
executed processes. Takes an integer between -20 (highest priority) and 19
(lowest priority). See
setpriority(2) for details.
OOMScoreAdjust=
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 proc.txt[1] for details.
IOSchedulingClass=
Sets the IO scheduling class for executed processes.
Takes an integer between 0 and 3 or one of the strings
none,
realtime,
best-effort or
idle. See
ioprio_set(2)
for details.
IOSchedulingPriority=
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
ioprio_set(2) for details.
CPUSchedulingPolicy=
Sets the CPU scheduling policy for executed processes.
Takes one of
other,
batch,
idle,
fifo or
rr. See
sched_setscheduler(2) for details.
CPUSchedulingPriority=
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
sched_setscheduler(2) for details.
CPUSchedulingResetOnFork=
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
sched_setscheduler(2) for details. Defaults to false.
CPUAffinity=
Controls the CPU affinity of the executed processes.
Takes a list of CPU indices or ranges separated by either whitespace or
commas. CPU ranges are specified by the lower and upper CPU indices separated
by a dash. This option may be specified more than once in which case the
specified CPU affinity masks are merged. If the empty string is assigned, the
mask is reset, all assignments prior to this will have no effect. See
sched_setaffinity(2) for details.
UMask=
Controls the file mode creation mask. Takes an access
mode in octal notation. See
umask(2) for details. Defaults to
0022.
Environment=
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.
Example:
Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"
gives three variables "VAR1", "VAR2",
"VAR3" with the values "word1 word2", "word3",
"$word 5 6".
See environ(7) for details about environment variables.
EnvironmentFile=
Similar to
Environment= 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 (").
The argument passed should be an absolute filename or wildcard
expression, optionally prefixed with "-", 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.
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
Environment=. 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.
PassEnvironment=
Pass environment variables from the systemd system
manager to executed processes. Takes a space-separated list of variable names.
This option may be specified more than once, in which case all listed
variables will be set. If the empty string is assigned to this option, the
list of environment variables is reset, all prior assignments have no effect.
Variables that are not set in the system manager will not be passed and will
be silently ignored.
Variables passed from this setting are overridden by those passed
from Environment= or EnvironmentFile=.
Example:
PassEnvironment=VAR1 VAR2 VAR3
passes three variables "VAR1", "VAR2",
"VAR3" with the values set for those variables in PID1.
See environ(7) for details about environment variables.
StandardInput=
Controls where file descriptor 0 (STDIN) of the executed
processes is connected to. Takes one of
null,
tty,
tty-force,
tty-fail or
socket.
If null is selected, standard input will be connected to
/dev/null, i.e. all read attempts by the process will result in immediate
EOF.
If tty is selected, standard input is connected to a TTY
(as configured by TTYPath=, 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.
tty-force is similar to tty, but the executed
process is forcefully and immediately made the controlling process of the
terminal, potentially removing previous controlling processes from the
terminal.
tty-fail is similar to tty but if the terminal
already has a controlling process start-up of the executed process
fails.
The socket option is only valid in socket-activated
services, and only when the socket configuration file (see
systemd.socket(5) 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 inetd(8) daemon.
This setting defaults to null.
StandardOutput=
Controls where file descriptor 1 (STDOUT) of the executed
processes is connected to. Takes one of
inherit,
null,
tty,
journal,
syslog,
kmsg,
journal+console,
syslog+console,
kmsg+console or
socket.
inherit duplicates the file descriptor of standard input
for standard output.
null connects standard output to /dev/null, i.e. everything
written to it will be lost.
tty connects standard output to a tty (as configured via
TTYPath=, 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.
journal connects standard output with the journal which is
accessible via journalctl(1). Note that everything that is written to
syslog or kmsg (see below) is implicitly stored in the journal as well, the
specific two options listed below are hence supersets of this one.
syslog connects standard output to the syslog(3)
system syslog service, in addition to the journal. Note that the journal
daemon is usually configured to forward everything it receives to syslog
anyway, in which case this option is no different from journal.
kmsg connects standard output with the kernel log buffer
which is accessible via dmesg(1), in addition to the journal. The
journal daemon might be configured to send all logs to kmsg anyway, in which
case this option is no different from journal.
journal+console, syslog+console and
kmsg+console work in a similar way as the three options above but
copy the output to the system console as well.
socket connects standard output to a socket acquired via
socket activation. The semantics are similar to the same option of
StandardInput=.
This setting defaults to the value set with
DefaultStandardOutput= in systemd-system.conf(5), which
defaults to journal.
StandardError=
Controls where file descriptor 2 (STDERR) of the executed
processes is connected to. The available options are identical to those of
StandardOutput=, with one exception: if set to
inherit the file
descriptor used for standard output is duplicated for standard error. This
setting defaults to the value set with
DefaultStandardError= in
systemd-system.conf(5), which defaults to
inherit.
TTYPath=
Sets the terminal device node to use if standard input,
output, or error are connected to a TTY (see above). Defaults to
/dev/console.
TTYReset=
Reset the terminal device specified with TTYPath=
before and after execution. Defaults to "no".
TTYVHangup=
Disconnect all clients which have opened the terminal
device specified with TTYPath= before and after execution. Defaults to
"no".
TTYVTDisallocate=
If the terminal device specified with TTYPath= 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 "no".
SyslogIdentifier=
Sets the process name to prefix log lines sent to the
logging system or the kernel log buffer with. If not set, defaults to the
process name of the executed process. This option is only useful when
StandardOutput= or StandardError= are set to syslog,
journal or kmsg (or to the same settings in combination with
+console).
SyslogFacility=
Sets the syslog facility to use when logging to syslog.
One of
kern,
user,
mail,
daemon,
auth,
syslog,
lpr,
news,
uucp,
cron,
authpriv,
ftp,
local0,
local1,
local2,
local3,
local4,
local5,
local6 or
local7.
See
syslog(3) for details. This option is only useful when
StandardOutput= or
StandardError= are set to
syslog.
Defaults to
daemon.
SyslogLevel=
Default syslog level to use when logging to syslog or the
kernel log buffer. One of
emerg,
alert,
crit,
err,
warning,
notice,
info,
debug. See
syslog(3)
for details. This option is only useful when
StandardOutput= or
StandardError= are set to
syslog or
kmsg. 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
SyslogLevelPrefix=, see below. For details see
sd-daemon(3).
Defaults to
info.
SyslogLevelPrefix=
Takes a boolean argument. If true and
StandardOutput= or
StandardError= are set to
syslog,
kmsg or
journal, 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
sd-daemon(3). Defaults to true.
TimerSlackNSec=
Sets the timer slack in nanoseconds for the executed
processes. The timer slack controls the accuracy of wake-ups triggered by
timers. See
prctl(2) 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.
LimitCPU=, LimitFSIZE=, LimitDATA=,
LimitSTACK=, LimitCORE=, LimitRSS=,
LimitNOFILE=, LimitAS=, LimitNPROC=,
LimitMEMLOCK=, LimitLOCKS=, LimitSIGPENDING=,
LimitMSGQUEUE=, LimitNICE=, LimitRTPRIO=,
LimitRTTIME=
These settings set both soft and hard limits of various
resources for executed processes. See
setrlimit(2) for details. The
resource limit is possible to specify in two formats,
value to set soft
and hard limits to the same value, or
soft:hard to set both limits
individually (e.g. LimitAS=4G:16G). Use the string
infinity to
configure no limit on a specific resource. The multiplicative suffixes K
(=1024), M (=1024*1024) and so on for G, T, P and E may be used for resource
limits measured in bytes (e.g. LimitAS=16G). For the limits referring to time
values, the usual time units ms, s, min, h and so on may be used (see
systemd.time(7) for details). Note that if no time unit is specified
for
LimitCPU= the default unit of seconds is implied, while for
LimitRTTIME= the default unit of microseconds is implied. Also, note
that the effective granularity of the limits might influence their
enforcement. For example, time limits specified for
LimitCPU= will be
rounded up implicitly to multiples of 1s. For
LimitNICE= the value may
be specified in two syntaxes: if prefixed with "+" or "-",
the value is understood as regular Linux nice value in the range -20..19. If
not prefixed like this the value is understood as raw resource limit parameter
in the range 0..40 (with 0 being equivalent to 1).
Note that most process resource limits configured with these
options are per-process, and processes may fork in order to acquire a new
set of resources that are accounted independently of the original process,
and may thus escape limits set. Also note that LimitRSS= is not
implemented on Linux, and setting it has no effect. Often it is advisable to
prefer the resource controls listed in systemd.resource-control(5)
over these per-process limits, as they apply to services as a whole, may be
altered dynamically at runtime, and are generally more expressive. For
example, MemoryLimit= is a more powerful (and working) replacement
for LimitRSS=.
Table 1. Limit directives and their equivalent
with ulimit
| Directive |
ulimit equivalent |
Unit |
| LimitCPU= |
ulimit -t |
Seconds |
| LimitFSIZE= |
ulimit -f |
Bytes |
| LimitDATA= |
ulimit -d |
Bytes |
| LimitSTACK= |
ulimit -s |
Bytes |
| LimitCORE= |
ulimit -c |
Bytes |
| LimitRSS= |
ulimit -m |
Bytes |
| LimitNOFILE= |
ulimit -n |
Number of File Descriptors |
| LimitAS= |
ulimit -v |
Bytes |
| LimitNPROC= |
ulimit -u |
Number of Processes |
| LimitMEMLOCK= |
ulimit -l |
Bytes |
| LimitLOCKS= |
ulimit -x |
Number of Locks |
| LimitSIGPENDING= |
ulimit -i |
Number of Queued Signals |
| LimitMSGQUEUE= |
ulimit -q |
Bytes |
| LimitNICE= |
ulimit -e |
Nice Level |
| LimitRTPRIO= |
ulimit -r |
Realtime Priority |
| LimitRTTIME= |
No equivalent |
Microseconds |
PAMName=
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
User=
setting. If not set, no PAM session will be opened for the executed processes.
See
pam(8) for details.
CapabilityBoundingSet=
Controls which capabilities to include in the capability
bounding set for the executed process. See
capabilities(7) for details.
Takes a whitespace-separated list of capability names as read by
cap_from_name(3), e.g.
CAP_SYS_ADMIN,
CAP_DAC_OVERRIDE,
CAP_SYS_PTRACE. 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 affects the respective
capabilities in the effective, permitted and inheritable capability sets, on
top of what
Capabilities= 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 "~" (without
any further argument), the bounding set is reset to the full set of available
capabilities, also undoing any previous settings.
AmbientCapabilities=
Controls which capabilities to include in the ambient
capability set for the executed process. Takes a whitespace-separated list of
capability names as read by
cap_from_name(3), e.g.
CAP_SYS_ADMIN,
CAP_DAC_OVERRIDE,
CAP_SYS_PTRACE. This
option may appear more than once in which case the ambient capability sets are
merged. If the list of capabilities is prefixed with "~", all but
the listed capabilities will be included, the effect of the assignment
inverted. If the empty string is assigned to this option, the ambient
capability set is reset to the empty capability set, and all prior settings
have no effect. If set to "~" (without any further argument), the
ambient capability set is reset to the full set of available capabilities,
also undoing any previous settings. Note that adding capabilities to ambient
capability set adds them to the process's inherited capability set.
Ambient capability sets are useful if you want to execute a
process as a non-privileged user but still want to give it some
capabilities. Note that in this case option keep-caps is
automatically added to SecureBits= to retain the capabilities over
the user change.
SecureBits=
Controls the secure bits set for the executed process.
Takes a space-separated combination of options from the following list:
keep-caps,
keep-caps-locked,
no-setuid-fixup,
no-setuid-fixup-locked,
noroot, and
noroot-locked. This
option may appear more than once in which case the secure bits are ORed. If
the empty string is assigned to this option, the bits are reset to 0. See
capabilities(7) for details.
Capabilities=
Controls the
capabilities(7) set for the executed
process. Take a capability string describing the effective, permitted and
inherited capability sets as documented in
cap_from_text(3). Note that
these capability sets are usually influenced (and filtered) by the
capabilities attached to the executed file. Due to that
CapabilityBoundingSet= is probably a much more useful setting.
ReadWriteDirectories=, ReadOnlyDirectories=,
InaccessibleDirectories=
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
ReadWriteDirectories=
are accessible from within the namespace with the same access rights as from
outside. Directories listed in
ReadOnlyDirectories= are accessible for
reading only, writing will be refused even if the usual file access controls
would permit this. Directories listed in
InaccessibleDirectories= 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.
Paths in ReadOnlyDirectories= and
InaccessibleDirectories= may be prefixed with "-", 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.
PrivateTmp=
Takes a boolean argument. If true, sets up a new file
system namespace for the executed processes and mounts private /tmp and
/var/tmp 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 /tmp or /var/tmp 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 /tmp and /var/tmp namespace by
using the
JoinsNamespaceOf= directive, see
systemd.unit(5) 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.
PrivateDevices=
Takes a boolean argument. If true, sets up a new /dev
namespace for the executed processes and only adds API pseudo devices such as
/dev/null, /dev/zero or /dev/random (as well as the pseudo TTY subsystem) to
it, but no physical devices such as /dev/sda. This is useful to securely turn
off physical device access by the executed process. Defaults to false.
Enabling this option will also remove
CAP_MKNOD from the capability
bounding set for the unit (see above), and set
DevicePolicy=closed (see
systemd.resource-control(5) 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.
PrivateNetwork=
Takes a boolean argument. If true, sets up a new network
namespace for the executed processes and configures only the loopback network
device "lo" 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
JoinsNamespaceOf= directive, see
systemd.unit(5) 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).
ProtectSystem=
Takes a boolean argument or "full". If true,
mounts the /usr and /boot directories read-only for processes invoked by this
unit. If set to "full", the /etc 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 CapabilityBoundingSet=. Defaults to off.
ProtectHome=
Takes a boolean argument or "read-only". If
true, the directories /home, /root and /run/user are made inaccessible and
empty for processes invoked by this unit. If set to "read-only", the
three directories are made read-only instead. It is recommended to enable this
setting for all long-running services (in particular network-facing ones), to
ensure they cannot get access to private user data, unless the services
actually require access to the user's private data. Note however that
processes retaining the CAP_SYS_ADMIN capability can undo the effect of this
setting. This setting is hence particularly useful for daemons which have this
capability removed, for example with CapabilityBoundingSet=. Defaults
to off.
MountFlags=
Takes a mount propagation flag:
shared,
slave or
private, which control whether mounts in the file
system namespace set up for this unit's processes will receive or propagate
mounts or unmounts. See
mount(2) for details. Defaults to
shared. Use
shared to ensure that mounts and unmounts are
propagated from the host to the container and vice versa. Use
slave to
run processes so that none of their mounts and unmounts will propagate to the
host. Use
private to also ensure that no mounts and unmounts from the
host will propagate into the unit processes' namespace. Note that
slave
means that file systems mounted on the host might stay mounted continuously in
the unit's namespace, and thus keep the device busy. Note that the file system
namespace related options (
PrivateTmp=,
PrivateDevices=,
ProtectSystem=,
ProtectHome=,
ReadOnlyDirectories=,
InaccessibleDirectories= and
ReadWriteDirectories=) require that
mount and unmount propagation from the unit's file system namespace is
disabled, and hence downgrade
shared to
slave.
UtmpIdentifier=
Takes a four character identifier string for an utmp/wtmp
entry for this service. This should only be set for services such as
getty 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.
SELinuxContext=
Set the SELinux security context of the executed process.
If set, this will override the automated domain transition. However, the
policy still needs to authorize the transition. This directive is ignored if
SELinux is disabled. If prefixed by "-", all errors will be ignored.
See
setexeccon(3) for details.
AppArmorProfile=
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 "-", all errors will be
ignored.
SmackProcessLabel=
Takes a
SMACK64 security label as argument. The
process executed by the unit will be started under this label and SMACK will
decide whether the processes is allowed to run or not based on it. The process
will continue to run under the label specified here unless the executable has
its own
SMACK64EXEC label, in which case the process will transition to
run under that label. When not specified, the label that systemd is running
under is used. This directive is ignored if SMACK is disabled.
The value may be prefixed by "-", in which case all
errors will be ignored. An empty value may be specified to unset previous
assignments.
IgnoreSIGPIPE=
Takes a boolean argument. If true, causes SIGPIPE
to be ignored in the executed process. Defaults to true because SIGPIPE
generally is useful only in shell pipelines.
NoNewPrivileges=
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.
SystemCallFilter=
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
SIGSYS signal (whitelisting). If the first character of the list is
"~", 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,
NoNewPrivileges=yes 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
execve,
rt_sigreturn,
sigreturn,
exit_group,
exit 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.
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 read
and write, and right after it add a blacklisting of write,
then write will be removed from the set.)
SystemCallErrorNumber=
Takes an "errno" error number name to return
when the system call filter configured with SystemCallFilter= is
triggered, instead of terminating the process immediately. Takes an error name
such as EPERM, EACCES or EUCLEAN. When this setting is
not used, or when the empty string is assigned, the process will be terminated
immediately when the filter is triggered.
SystemCallArchitectures=
Takes a space separated list of architecture identifiers
to include in the system call filter. The known architecture identifiers are
x86, x86-64, x32, arm as well as the special
identifier native. 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 native 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,
NoNewPrivileges=yes is implied. Note that setting this option to a
non-empty list implies that native is included too. By default, this
option is set to the empty list, i.e. no architecture system call filtering is
applied.
RestrictAddressFamilies=
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
AF_UNIX,
AF_INET or
AF_INET6.
When prefixed with
~ the listed address families will be applied as
blacklist, otherwise as whitelist. Note that this restricts access to the
socket(2) system call only. Sockets passed into the process by other
means (for example, by using socket activation with socket units, see
systemd.socket(5)) are unaffected. Also, sockets created with
socketpair() (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,
NoNewPrivileges=yes 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.
Use this option to limit exposure of processes to remote systems,
in particular via exotic network protocols. Note that in most cases, the
local AF_UNIX address family should be included in the configured
whitelist as it is frequently used for local communication, including for
syslog(2) logging.
Personality=
Controls which kernel architecture
uname(2) shall
report, when invoked by unit processes. Takes one of
x86 and
x86-64. 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.
RuntimeDirectory=, RuntimeDirectoryMode=
Takes a list of directory names. If set, one or more
directories by the specified names will be created below /run (for system
services) or below
$XDG_RUNTIME_DIR (for user services) when the unit
is started, and removed when the unit is stopped. The directories will have
the access mode specified in
RuntimeDirectoryMode=, and will be owned
by the user and group specified in
User= and
Group=. 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 "/", i.e. must refer to simple directories to create
or remove. This is particularly useful for unprivileged daemons that cannot
create runtime directories in /run 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
tmpfiles.d(5).