phpman > man > systemd-notify(1)

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



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

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

DESCRIPTION
       systemd-notify may be called by daemon scripts to notify the init system 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 set for the service unit this command is called from.

       Note that sd_notify() notifications may be attributed to units correctly only if either the
       sending process is still around at the time PID 1 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. When --no-block is used, all 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.

       Hence, systemd-notify will first attempt to invoke sd_notify() pretending to have the PID of
       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
       The following options are understood:

       --ready
           Inform the init system about service start-up completion. This is equivalent to
           systemd-notify READY=1. For details about the semantics of this option see sd_notify(3).

       --pid=
           Inform the service manager about the main PID of the daemon. 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. This is equivalent to systemd-notify MAINPID=$PID. For details about the
           semantics of this option see sd_notify(3).

       --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.

       --status=
           Send a free-form status string for the daemon to the init systemd. 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).

       --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.

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

       --version
           Print a short version string and exit.

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

EXAMPLE
       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:

           #!/bin/bash

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

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

                   # Do something with $a ...

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

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



systemd 249                                                                        SYSTEMD-NOTIFY(1)