NAME
systemd-notify - Notify service manager about start-up completion and other daemon status changesSYNOPSIS
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: --readyInform 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/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
SEE ALSO
systemd(1), systemctl(1), systemd.unit(5), sd_notify(3), sd_booted(3)systemd 252 |