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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLE | SEE ALSO | COLOPHON |
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. 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.
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.
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:
#!/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
systemd(1), systemctl(1), systemd.unit(5), sd_notify(3), sd_booted(3)
This page is part of the systemd (systemd system and service manager)
project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a bug
report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩. This
page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2020-08-13. (At that
time, the date of the most recent commit that was found in the repos‐
itory was 2020-08-11.) If you discover any rendering problems in
this HTML version of the page, or you believe there is a better or
more up-to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not part
of the original manual page), send a mail to man-pages@man7.org
systemd 246 SYSTEMD-NOTIFY(1)
Pages that refer to this page: init(1) , systemd(1) , 30-systemd-environment-d-generator(7) , systemd.directives(7) , systemd.index(7)