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

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 sd_notify(3).

       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.

Example1.Start-upNotificationandStatusUpdates

       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:

           #!/bin/sh

           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..."
           done

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

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

       The following options are understood:

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

       --reloading
           Inform the invoking service manager about the beginning of a configuration reload cycle. This is
           equivalent to systemd-notifyRELOADING=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.

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

           Added in version 253.

       --pid=
           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.  --pid=auto is equivalent to systemd-notify--pid=$PID. For
           details about the semantics of this option see sd_notify(3).

           systemd-notify will first attempt to invoke sd_notify() pretending to have the PID specified with
           --pid=. This will only succeed when invoked with sufficient privileges. On failure, it will then fall
           back to invoking it under its own PID. Effectively, this means that a privileged invocation of
           systemd-notify--pid= may circumvent NotifyAccess=main or NotifyAccess=exec restrictions enforced for
           a service.

           If this switch is used in an unprivileged 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.

       --uid=USER
           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.

       --status=
           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-notifySTATUS=.... 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.

       --booted
           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.

       --no-block
           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.

       --exec
           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.

       --fd=
           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.

       --fdname=
           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.

       --version
           Print a short version string and exit.

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

systemd 257.4                                                                                  SYSTEMD-NOTIFY(1)

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

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