notify(1) - Linux manual page (original) (raw)
SYSTEMD-NOTIFY(1) systemd-notify SYSTEMD-NOTIFY(1)
NAME top
systemd-notify - Notify service manager about start-up completion
and other daemon status changesSYNOPSIS top
**systemd-notify** [OPTIONS...] [VARIABLE=VALUE...]
**systemd-notify** [--exec] [OPTIONS...] [VARIABLE=VALUE...] [;]
[CMDLINE...]DESCRIPTION top
**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)](../man3/sd%5Fnotify.3.html).
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)](../man5/systemd.service.5.html)
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 top
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)](../man3/sd%5Fnotify.3.html).
**--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
_MONOTONICUSEC=_ field as required for _Type=notify-reload_
services, see [systemd.service(5)](../man5/systemd.service.5.html) for details). For details
about the semantics of this option see [sd_notify(3)](../man3/sd%5Fnotify.3.html).
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)](../man3/sd%5Fnotify.3.html).
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)](../man3/sd%5Fnotify.3.html).
**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)](../man5/systemd.service.5.html) 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)](../man3/sd%5Fnotify.3.html).
This information is shown in [systemctl(1)](../man1/systemctl.1.html)'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)](../man3/sd%5Fbooted.3.html). An
alternate way to check for this state is to call [systemctl(1)](../man1/systemctl.1.html)
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.
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)](../man5/systemd.service.5.html) 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)](../man1/bash.1.html) shell, use an
expression like the following:
systemd-notify --fd=4 --fd=5 4</some/file 5</some/other/file
Added in version 254.
**--fdname=**
Set a name to assign to the file descriptors passed via **--fd=**
(see above). This controls the "FDNAME=" field. This setting
may only be specified once, and applies to all file
descriptors passed. Invoke this tool multiple times in case
multiple file descriptors with different file descriptor names
shall be submitted.
Added in version 254.
**-h**, **--help**
Print a short help text and exit.
**--version**
Print a short version string and exit.EXIT STATUS top
On success, 0 is returned, a non-zero failure code otherwise.EXAMPLE top
**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..."
doneSEE ALSO top
[systemd(1)](../man1/systemd.1.html), [systemctl(1)](../man1/systemctl.1.html), [systemd.unit(5)](../man5/systemd.unit.5.html), [systemd.service(5)](../man5/systemd.service.5.html),
[sd_notify(3)](../man3/sd%5Fnotify.3.html), [sd_booted(3)](../man3/sd%5Fbooted.3.html)COLOPHON top
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(which is _not_ part of the original manual page), send a mail to
man-pages@man7.orgsystemd 258~devel SYSTEMD-NOTIFY(1)
Pages that refer to this page:systemd(1), systemd.directives(7), systemd.index(7)