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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | EXAMPLE | SEE ALSO | COLOPHON |
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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/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
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 2022-12-17. (At that
time, the date of the most recent commit that was found in the
repository was 2022-12-16.) 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 252 SYSTEMD-NOTIFY(1)
Pages that refer to this page: systemd(1), systemd.directives(7), systemd.index(7)
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