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/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 SYSTEMD-NOTIFY(1)
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