Manual: systemd-notify
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...]
systemd-notify --exec [OPTIONS...] [VARIABLE=VALUE...] ; -- {CMDLINE...}
systemd-notify --fork [OPTIONS...] -- {CMDLINE...}
DESCRIPTION
systemd-notify may be called by service scripts to notify the invoking service manager 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 appropriately set
for the service unit this command is called from. See systemd.service(5) for details.
Note that sd_notify() notifications may be attributed to units correctly only if either the sending process is still
around at the time the service manager 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. To address this systemd-notify will wait
until the notification message has been processed by the service manager. When --no-block is used, this
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.
systemd-notify will first attempt to invoke sd_notify() pretending to have the PID of the parent process of
systemd-notify (i.e. 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 invoking service manager about service start-up or configuration reload completion. This is equivalent
to systemd-notify READY=1. For details about the semantics of this option see sd_notify(3).
--reloading
Inform the invoking service manager about the beginning of a configuration reload cycle. This is equivalent to
systemd-notify RELOADING=1 (but implicitly also sets a MONOTONIC_USEC= field as required for Type=notify-reload
services, see systemd.service(5) for details). For details about the semantics of this option see sd_notify(3).
Added in version 253.
--stopping
Inform the invoking service manager about the beginning of the shutdown phase of the service. This is equivalent
to systemd-notify STOPPING=1. For details about the semantics of this option see sd_notify(3).
Added in version 253.
--pid=
Inform the service manager about the main PID of the service. 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. --pid=auto is
equivalent to systemd-notify --pid=$PID. For details about the semantics of this option see sd_notify(3).
systemd-notify will first attempt to invoke sd_notify() pretending to have the PID specified with --pid=. This
will only succeed when invoked with sufficient privileges. On failure, it will then fall back to invoking it
under its own PID. Effectively, this means that a privileged invocation of systemd-notify --pid= may circumvent
NotifyAccess=main or NotifyAccess=exec restrictions enforced for a service.
If this switch is used in an unprivileged systemd-notify invocation from a process that shall become the new main
process of a service — and which is not the process forked off by the service manager (or the current main
process) —, then it is essential to set NotifyAccess=all in the service unit file, or otherwise the notification
will be ignored for security reasons. See systemd.service(5) for details.
--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.
Added in version 237.
--status=
Send a free-form human-readable status string for the daemon to the service manager. 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). This information is shown in systemctl(1)'s status output, among other places.
--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 output "offline" if the system was not booted with systemd, though the return value has a
different meaning.
--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.
Added in version 246.
--exec
If specified systemd-notify will execute another command line after it completed its operation, replacing its own
process. If used, the list of assignments to include in the message sent must be followed by a ";" character (as
separate argument), followed by the command line to execute. This permits "chaining" of commands, i.e. issuing
one operation, followed immediately by another, without changing PIDs.
Note that many shells interpret ";" as their own separator for command lines, hence when systemd-notify is
invoked from a shell the semicolon must usually be escaped as "\;".
Added in version 254.
--fd=
Send a file descriptor along with the notification message. This is useful when invoked in services that have the
FileDescriptorStoreMax= setting enabled, see systemd.service(5) for details. The specified file descriptor must
be passed to systemd-notify when invoked. This option may be used multiple times to pass multiple file
descriptors in a single notification message.
To use this functionality from a bash(1) shell, use an expression like the following:
systemd-notify --fd=4 --fd=5 4systemd(1), systemctl(1), systemd.unit(5), systemd.service(5), sd_notify(3), sd_booted(3)
systemd 259.5 SYSTEMD-NOTIFY(1)