SYSTEMD-NOTIFY(1) systemd-notify SYSTEMD-NOTIFY(1)
systemd-notify - Notify service manager about start-up completion and
other daemon status changes
systemd-notify [OPTIONS...] [VARIABLE=VALUE...]
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.
The following options are understood:
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).
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).
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.
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).
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.
Print a short help text and exit.
Print a short version string and exit.
On success, 0 is returned, a non-zero failure code otherwise.
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:
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..."
systemd(1), systemctl(1), systemd.unit(5), sd_notify(3), sd_booted(3)
systemd 237 SYSTEMD-NOTIFY(1)
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