systemd.exec(5) - Execution environment configuration



  • SYSTEMD.EXEC(5)			 systemd.exec		       SYSTEMD.EXEC(5)
    
    
    
    NAME
           systemd.exec - Execution environment configuration
    
    SYNOPSIS
           service.service, socket.socket, mount.mount, swap.swap
    
    DESCRIPTION
           Unit configuration files for services, sockets, mount points, and swap
           devices share a subset of configuration options which define the
           execution environment of spawned processes.
    
           This man page lists the configuration options shared by these four unit
           types. See systemd.unit(5) for the common options of all unit
           configuration files, and systemd.service(5), systemd.socket(5),
           systemd.swap(5), and systemd.mount(5) for more information on the
           specific unit configuration files. The execution specific configuration
           options are configured in the [Service], [Socket], [Mount], or [Swap]
           sections, depending on the unit type.
    
    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.
    <standard input>:1128: warning [p 13, 0.7i, div `3tbd1,1', 0.0i]: can't break line
    
    	   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
    <standard input>:1303: warning [p 13, 5.3i, div `3tbd11,2', 0.5i]: can't break line
    	   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
    <standard input>:1310: warning [p 13, 5.3i, div `3tbd12,2', 0.3i]: can't break line
    	   +-----------------+-------------------+---------------------+
    	   |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:
    <standard input>:1331: warning [p 13, 5.3i, div `3tbd15,2', 0.2i]: can't break line
    	   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
    <standard input>:1413: warning [p 13, 5.3i, div `3tbd27,1', 0.0i]: can't break line
    <standard input>:1469: warning [p 13, 5.3i, div `3tbd35,1', 0.0i]: can't break line
    <standard input>:1504: warning [p 13, 5.3i, div `3tbd40,1', 0.0i]: can't break line
    warning: file `<standard input>', around line 1186:
      table wider than line width
    <standard input>:1535: warning [p 14, 1.8i]: can't break line
    	   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).
    
    ENVIRONMENT VARIABLES IN SPAWNED PROCESSES
           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.
    
           $PATH
    	   Colon-separated list of directories to use when launching
    	   executables. Systemd uses a fixed value of
    	   /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin.
    
           $LANG
    	   Locale. Can be set in locale.conf(5) or on the kernel command line
    	   (see systemd(1) and kernel-command-line(7)).
    
           $USER, $LOGNAME, $HOME, $SHELL
    	   User name (twice), home directory, and the login shell. The
    	   variables are set for the units that have User= set. See passwd(5).
    
           $XDG_RUNTIME_DIR
    	   The directory for volatile state. Set in user sessions. See
    	   pam_systemd(8).
    
           $XDG_SESSION_ID, $XDG_SEAT, $XDG_VTNR
    	   The identifier of the session, the seat name, and virtual terminal
    	   of the session. Set by pam_systemd(8) for login sessions.
    	   $XDG_SEAT and $XDG_VTNR will only be set when attached to a seat
    	   and a tty.
    
           $MAINPID
    	   The PID of the units main process if it is known. This is only set
    	   for control processes as invoked by ExecReload= and similar.
    
           $LISTEN_FDS, $LISTEN_PID
    	   Information about file descriptors passed to a service for socket
    	   activation. See sd_listen_fds(3).
    
           $TERM
    	   Terminal type, set only for units connected to a terminal
    	   (StandardInput=tty, StandardOutput=tty, or StandardError=tty). See
    	   termcap(5).
    
           Additional variables may be configured by the following means: for
           processes spawned in specific units, use the Environment= and
           EnvironmentFile= options above; to specify variables globally, use
           DefaultEnvironment= (see systemd-system.conf(5)) or the kernel option
           systemd.setenv= (see systemd(1)). Additional variables may also be set
           through PAM, cf. pam_env(8).
    
    PROCESS EXIT CODES
           When invoking a unit process the service manager possibly fails to
           apply the execution parameters configured with the settings above. In
           that case the already created service process will exit with a non-zero
           exit code before the configured command line is executed. (Or in other
           words, the child process possibly exits with these error codes, after
           having been created by the fork(2) system call, but before the matching
           execve(2) system call is called.) Specifically, exit codes defined by
           the C library, by the LSB specification and by the systemd service
           manager itself are used.
    
           The following basic service exit codes are defined by the C library.
    
           Table 2. Basic C library exit codes
           +----------+---------------+--------------------+
           |Exit Code | Symbolic Name | Description	       |
           +----------+---------------+--------------------+
           |0	  | EXIT_SUCCESS  | Generic success    |
           |	  |		  | code.	       |
           +----------+---------------+--------------------+
           |1	  | EXIT_FAILURE  | Generic failure or |
           |	  |		  | unspecified error. |
           +----------+---------------+--------------------+
    
           The following service exit codes are defined by the LSB
           specification[2].
    
           Table 3. LSB service exit codes
           +----------+----------------------+--------------------+
           |Exit Code | Symbolic Name	 | Description	      |
           +----------+----------------------+--------------------+
           |2	  | EXIT_INVALIDARGUMENT | Invalid or excess  |
           |	  |			 | arguments.	      |
           +----------+----------------------+--------------------+
           |3	  | EXIT_NOTIMPLEMENTED	 | Unimplemented      |
           |	  |			 | feature.	      |
           +----------+----------------------+--------------------+
           |4	  | EXIT_NOPERMISSION	 | The user has	      |
           |	  |			 | insufficient	      |
           |	  |			 | privileges.	      |
           +----------+----------------------+--------------------+
           |5	  | EXIT_NOTINSTALLED	 | The program is not |
           |	  |			 | installed.	      |
           +----------+----------------------+--------------------+
           |6	  | EXIT_NOTCONFIGURED	 | The program is not |
           |	  |			 | configured.	      |
           +----------+----------------------+--------------------+
           |7	  | EXIT_NOTRUNNING	 | The program is not |
           |	  |			 | running.	      |
           +----------+----------------------+--------------------+
    
           The LSB specification suggests that error codes 200 and above are
           reserved for implementations. Some of them are used by the service
           manager to indicate problems during process invocation:
    
           Table 4. systemd-specific exit codes
           +----------+------------------------------+---------------------------------------------+
           |Exit Code | Symbolic Name		 | Description			       |
           +----------+------------------------------+---------------------------------------------+
           |200	  | EXIT_CHDIR			 | Changing to the		       |
           |	  |				 | requested working		       |
           |	  |				 | directory failed.		       |
           |	  |				 | See				       |
           |	  |				 | WorkingDirectory=		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |201	  | EXIT_NICE			 | Failed to set up		       |
           |	  |				 | process scheduling		       |
           |	  |				 | priority (nice		       |
           |	  |				 | level). See Nice=		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |202	  | EXIT_FDS			 | Failed to close		       |
           |	  |				 | unwanted file		       |
           |	  |				 | descriptors, or to		       |
           |	  |				 | adjust passed file		       |
           |	  |				 | descriptors.			       |
           +----------+------------------------------+---------------------------------------------+
           |203	  | EXIT_EXEC			 | The actual process		       |
           |	  |				 | execution failed		       |
           |	  |				 | (specifically, the		       |
           |	  |				 | execve(2) system		       |
           |	  |				 | call). Most likely		       |
           |	  |				 | this is caused by a		       |
           |	  |				 | missing or			       |
           |	  |				 | non-accessible		       |
           |	  |				 | executable file.		       |
           +----------+------------------------------+---------------------------------------------+
           |204	  | EXIT_MEMORY			 | Failed to perform		       |
           |	  |				 | an action due to		       |
           |	  |				 | memory shortage.		       |
           +----------+------------------------------+---------------------------------------------+
           |205	  | EXIT_LIMITS			 | Failed to adjust		       |
           |	  |				 | resoure limits. See		       |
           |	  |				 | LimitCPU= and		       |
           |	  |				 | related settings		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |206	  | EXIT_OOM_ADJUST		 | Failed to adjust		       |
           |	  |				 | the OOM setting.		       |
           |	  |				 | See OOMScoreAdjust=		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |207	  | EXIT_SIGNAL_MASK		 | Failed to set		       |
           |	  |				 | process signal		       |
           |	  |				 | mask.			       |
           +----------+------------------------------+---------------------------------------------+
           |208	  | EXIT_STDIN			 | Failed to set up		       |
           |	  |				 | standard input. See		       |
           |	  |				 | StandardInput=		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |209	  | EXIT_STDOUT			 | Failed to set up		       |
           |	  |				 | standard output.		       |
           |	  |				 | See StandardOutput=		       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |210	  | EXIT_CHROOT			 | Failed to change		       |
           |	  |				 | root directory		       |
           |	  |				 | (chroot(2)). See		       |
           |	  |				 | RootDirectory=/RootImage=	       |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |211	  | EXIT_IOPRIO			 | Failed to set up IO		       |
           |	  |				 | scheduling priority. See	       |
           |	  |				 | IOSchedulingClass=/IOSchedulingPriority=    |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |212	  | EXIT_TIMERSLACK		 | Failed to set up timer slack. See	       |
           |	  |				 | TimerSlackNSec= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |213	  | EXIT_SECUREBITS		 | Failed to set process secure bits. See      |
           |	  |				 | SecureBits= above.		       |
           +----------+------------------------------+---------------------------------------------+
           |214	  | EXIT_SETSCHEDULER		 | Failed to set up CPU scheduling. See	       |
           |	  |				 | CPUSchedulingPolicy=/CPUSchedulingPriority= |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |215	  | EXIT_CPUAFFINITY		 | Failed to set up CPU affinity. See	       |
           |	  |				 | CPUAffinity= above.		       |
           +----------+------------------------------+---------------------------------------------+
           |216	  | EXIT_GROUP			 | Failed to determine or change group	       |
           |	  |				 | credentials. See		       |
           |	  |				 | Group=/SupplementaryGroups= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |217	  | EXIT_USER			 | Failed to determine or change user	       |
           |	  |				 | credentials, or to set up user namespacing. |
           |	  |				 | See User=/PrivateUsers= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |218	  | EXIT_CAPABILITIES		 | Failed to drop capabilities, or apply       |
           |	  |				 | ambient capabilities. See	       |
           |	  |				 | CapabilityBoundingSet=/AmbientCapabilities= |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |219	  | EXIT_CGROUP			 | Setting up the service control group	       |
           |	  |				 | failed.			       |
           +----------+------------------------------+---------------------------------------------+
           |220	  | EXIT_SETSID			 | Failed to create new process session.       |
           +----------+------------------------------+---------------------------------------------+
           |221	  | EXIT_CONFIRM		 | Execution has been cancelled by the user.   |
           |	  |				 | See the systemd.confirm_spawn= kernel       |
           |	  |				 | command line setting on kernel-command-     |
           |	  |				 | line(7) for details.		       |
           +----------+------------------------------+---------------------------------------------+
           |222	  | EXIT_STDERR			 | Failed to set up standard error output. See |
           |	  |				 | StandardError= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |224	  | EXIT_PAM			 | Failed to set up PAM session. See PAMName=  |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |225	  | EXIT_NETWORK		 | Failed to set up network namespacing. See   |
           |	  |				 | PrivateNetwork= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |226	  | EXIT_NAMESPACE		 | Failed to set up mount namespacing. See     |
           |	  |				 | ReadOnlyPaths= and related settings above.  |
           +----------+------------------------------+---------------------------------------------+
           |227	  | EXIT_NO_NEW_PRIVILEGES	 | Failed to disable new priviliges. See       |
           |	  |				 | NoNewPrivileges=yes above.	       |
           +----------+------------------------------+---------------------------------------------+
           |228	  | EXIT_SECCOMP		 | Failed to apply system call filters. See    |
           |	  |				 | SystemCallFilter= and related settings      |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |229	  | EXIT_SELINUX_CONTEXT	 | Determining or changing SELinux context     |
           |	  |				 | failed. See SELinuxContext= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |230	  | EXIT_PERSONALITY		 | Failed to set up a execution domain	       |
           |	  |				 | (personality). See Personality= above.      |
           +----------+------------------------------+---------------------------------------------+
           |231	  | EXIT_APPARMOR_PROFILE	 | Failed to prepare changing AppArmor	       |
           |	  |				 | profile. See AppArmorProfile= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |232	  | EXIT_ADDRESS_FAMILIES	 | Failed to restrict address families. See    |
           |	  |				 | RestrictAddressFamilies= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |233	  | EXIT_RUNTIME_DIRECTORY	 | Setting up runtime directory failed. See    |
           |	  |				 | RuntimeDirectory= and related settings      |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
           |235	  | EXIT_CHOWN			 | Failed to adjust socket ownership. Used for |
           |	  |				 | socket units only.		       |
           +----------+------------------------------+---------------------------------------------+
           |236	  | EXIT_SMACK_PROCESS_LABEL	 | Failed to set SMACK label. See	       |
           |	  |				 | SmackProcessLabel= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |237	  | EXIT_KEYRING		 | Failed to set up kernel keyring.	       |
           +----------+------------------------------+---------------------------------------------+
           |238	  | EXIT_STATE_DIRECTORY	 | Failed to set up a the unit's state	       |
           |	  |				 | directory. See StateDirectory= above.       |
           +----------+------------------------------+---------------------------------------------+
           |239	  | EXIT_CACHE_DIRECTORY	 | Failed to set up a the unit's cache	       |
           |	  |				 | directory. See CacheDirectory= above.       |
           +----------+------------------------------+---------------------------------------------+
           |240	  | EXIT_LOGS_DIRECTORY		 | Failed to set up a the unit's logging       |
           |	  |				 | directory. See LogsDirectory= above.	       |
           +----------+------------------------------+---------------------------------------------+
           |241	  | EXIT_CONFIGURATION_DIRECTORY | Failed to set up a the unit's configuration |
           |	  |				 | directory. See ConfigurationDirectory=      |
           |	  |				 | above.			       |
           +----------+------------------------------+---------------------------------------------+
    
    SEE ALSO
           systemd(1), systemctl(1), journalctl(8), systemd.unit(5),
           systemd.service(5), systemd.socket(5), systemd.swap(5),
           systemd.mount(5), systemd.kill(5), systemd.resource-control(5),
           systemd.time(7), systemd.directives(7), tmpfiles.d(5), exec(3)
    
    NOTES
    	1. proc.txt
    	   https://www.kernel.org/doc/Documentation/filesystems/proc.txt
    
    	2. LSB specification
    	   https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
    
    
    
    systemd 219						       SYSTEMD.EXEC(5)
    

Log in to reply
 

© Lightnetics 2024