systemd-notify(1) — Linux manual page


SYSTEMD-NOTIFY(1)            systemd-notify            SYSTEMD-NOTIFY(1)

NAME         top

       systemd-notify - Notify service manager about start-up completion
       and other daemon status changes

SYNOPSIS         top

       systemd-notify [OPTIONS...] [VARIABLE=VALUE...]

       systemd-notify --exec [OPTIONS...] [VARIABLE=VALUE...] ;

DESCRIPTION         top

       systemd-notify may be called by service scripts to notify the
       invoking service manager about status changes. It can be used to
       send arbitrary information, encoded in an environment-block-like
       list of strings. Most importantly, it can be used for start-up
       completion notification.

       This is mostly just a wrapper around sd_notify() and makes this
       functionality available to shell scripts. For details see

       The command line may carry a list of environment variables to
       send as part of the status update.

       Note that systemd will refuse reception of status updates from
       this command unless NotifyAccess= is appropriately set for the
       service unit this command is called from. See systemd.service(5)
       for details.

       Note that sd_notify() notifications may be attributed to units
       correctly only if either the sending process is still around at
       the time the service manager processes the message, or if the
       sending process is explicitly runtime-tracked by the service
       manager. The latter is the case if the service manager originally
       forked off the process, i.e. on all processes that match
       NotifyAccess=main or NotifyAccess=exec. Conversely, if an
       auxiliary process of the unit sends an sd_notify() message and
       immediately exits, the service manager might not be able to
       properly attribute the message to the unit, and thus will ignore
       it, even if NotifyAccess=all is set for it. To address this
       systemd-notify will wait until the notification message has been
       processed by the service manager. When --no-block is used, this
       synchronization for reception of notifications is disabled, and
       hence the aforementioned race may occur if the invoking process
       is not the service manager or spawned by the service manager.

       systemd-notify will first attempt to invoke sd_notify()
       pretending to have the PID of the parent process of
       systemd-notify (i.e. the invoking process). This will only
       succeed when invoked with sufficient privileges. On failure, it
       will then fall back to invoking it under its own PID. This
       behaviour is useful in order that when the tool is invoked from a
       shell script the shell process — and not the systemd-notify
       process — appears as sender of the message, which in turn is
       helpful if the shell process is the main process of a service,
       due to the limitations of NotifyAccess=all. Use the --pid= switch
       to tweak this behaviour.

OPTIONS         top

       The following options are understood:

           Inform the invoking service manager about service start-up or
           configuration reload completion. This is equivalent to
           systemd-notify READY=1. For details about the semantics of
           this option see sd_notify(3).

           Inform the invoking service manager about the beginning of a
           configuration reload cycle. This is equivalent to
           systemd-notify RELOADING=1 (but implicitly also sets a
           MONOTONIC_USEC= field as required for Type=notify-reload
           services, see systemd.service(5) for details). For details
           about the semantics of this option see sd_notify(3).

           Added in version 253.

           Inform the invoking service manager about the beginning of
           the shutdown phase of the service. This is equivalent to
           systemd-notify STOPPING=1. For details about the semantics of
           this option see sd_notify(3).

           Added in version 253.

           Inform the service manager about the main PID of the service.
           Takes a PID as argument. If the argument is specified as
           "auto" or omitted, the PID of the process that invoked
           systemd-notify is used, except if that's the service manager.
           If the argument is specified as "self", the PID of the
           systemd-notify command itself is used, and if "parent" is
           specified the calling process' PID is used — even if it is
           the service manager. The latter is equivalent to
           systemd-notify MAINPID=$PID. For details about the semantics
           of this option see sd_notify(3).

           If this switch is used in an systemd-notify invocation from a
           process that shall become the new main process of a service —
           and which is not the process forked off by the service
           manager (or the current main process) —, then it is essential
           to set NotifyAccess=all in the service unit file, or
           otherwise the notification will be ignored for security
           reasons. See systemd.service(5) for details.

           Set the user ID to send the notification from. Takes a UNIX
           user name or numeric UID. When specified the notification
           message will be sent with the specified UID as sender, in
           place of the user the command was invoked as. This option
           requires sufficient privileges in order to be able manipulate
           the user identity of the process.

           Added in version 237.

           Send a free-form human readable status string for the daemon
           to the service manager. This option takes the status string
           as argument. This is equivalent to systemd-notify STATUS=....
           For details about the semantics of this option see
           sd_notify(3). This information is shown in systemctl(1)'s
           status output, among other places.

           Returns 0 if the system was booted up with systemd, non-zero
           otherwise. If this option is passed, no message is sent. This
           option is hence unrelated to the other options. For details
           about the semantics of this option, see sd_booted(3). An
           alternate way to check for this state is to call systemctl(1)
           with the is-system-running command. It will return "offline"
           if the system was not booted with systemd.

           Do not synchronously wait for the requested operation to
           finish. Use of this option is only recommended when
           systemd-notify is spawned by the service manager, or when the
           invoking process is directly spawned by the service manager
           and has enough privileges to allow systemd-notify to send the
           notification on its behalf. Sending notifications with this
           option set is prone to race conditions in all other cases.

           Added in version 246.

           If specified systemd-notify will execute another command line
           after it completed its operation, replacing its own process.
           If used, the list of assignments to include in the message
           sent must be followed by a ";" character (as separate
           argument), followed by the command line to execute. This
           permits "chaining" of commands, i.e. issuing one operation,
           followed immediately by another, without changing PIDs.

           Note that many shells interpret ";" as their own separator
           for command lines, hence when systemd-notify is invoked from
           a shell the semicolon must usually be escaped as "\;".

           Added in version 254.

           Send a file descriptor along with the notification message.
           This is useful when invoked in services that have the
           FileDescriptorStoreMax= setting enabled, see
           systemd.service(5) for details. The specified file descriptor
           must be passed to systemd-notify when invoked. This option
           may be used multiple times to pass multiple file descriptors
           in a single notification message.

           To use this functionality from a bash(1) shell, use an
           expression like the following:

               systemd-notify --fd=4 --fd=5 4</some/file 5</some/other/file

           Added in version 254.

           Set a name to assign to the file descriptors passed via --fd=
           (see above). This controls the "FDNAME=" field. This setting
           may only be specified once, and applies to all file
           descriptors passed. Invoke this tool multiple times in case
           multiple file descriptors with different file descriptor
           names shall be submitted.

           Added in version 254.

       -h, --help
           Print a short help text and exit.

           Print a short version string and exit.

EXIT STATUS         top

       On success, 0 is returned, a non-zero failure code otherwise.

EXAMPLE         top

       Example 1. Start-up Notification and Status Updates

       A simple shell daemon that sends start-up notifications after
       having set up its communication channel. During runtime it sends
       further status updates to the init system:


           mkfifo /tmp/waldo
           systemd-notify --ready --status="Waiting for data..."

           while : ; do
                   read -r a < /tmp/waldo
                   systemd-notify --status="Processing $a"

                   # Do something with $a ...

                   systemd-notify --status="Waiting for data..."

SEE ALSO         top

       systemd(1), systemctl(1), systemd.unit(5), systemd.service(5),
       sd_notify(3), sd_booted(3)

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨⟩.  If you have
       a bug report for this manual page, see
       This page was obtained from the project's upstream Git repository
       ⟨⟩ on 2023-12-22.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2023-12-22.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to

systemd 255                                            SYSTEMD-NOTIFY(1)

Pages that refer to this page: systemd(1)systemd.directives(7)systemd.index(7)