focal (1) systemd-notify.1.gz

Provided by: systemd_245.4-4ubuntu3.24_amd64 bug

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.

       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 described above.

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 init system about the main PID of the daemon. Takes a PID as argument. If the argument is
           omitted, the PID of the process that invoked systemd-notify is used. 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.

       -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)