X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsd_notify.xml;h=b7c33da63af35f44b8dc8b504a3f1720543ae670;hb=40780877c19ef408da8ab21f4156cfc153f94b5c;hp=3e530757ce41519cf98067bf5af8f8f13791bbcc;hpb=26e3ff59a6a197e442255d8adfa2df239405c7e5;p=elogind.git
diff --git a/man/sd_notify.xml b/man/sd_notify.xml
index 3e530757c..b7c33da63 100644
--- a/man/sd_notify.xml
+++ b/man/sd_notify.xml
@@ -21,7 +21,8 @@
along with systemd; If not, see .
-->
-
+
sd_notify
@@ -45,7 +46,10 @@
sd_notify
sd_notifyf
- Notify service manager about start-up completion and other daemon status changes
+ sd_pid_notify
+ sd_pid_notifyf
+ sd_pid_notify_with_fds
+ Notify service manager about start-up completion and other service status changes
@@ -64,17 +68,41 @@
const char *format
...
+
+
+ int sd_pid_notify
+ pid_t pid
+ int unset_environment
+ const char *state
+
+
+
+ int sd_pid_notifyf
+ pid_t pid
+ int unset_environment
+ const char *format
+ ...
+
+
+
+ int sd_pid_notify_with_fds
+ pid_t pid
+ int unset_environment
+ const char *state
+ const int *fds
+ unsigned n_fds
+
Description
- sd_notify() shall be called
- by a daemon to notify the init system about status
- changes. It can be used to send arbitrary information,
- encoded in an environment-block-like string. Most
- importantly it can be used for start-up completion
- notification.
+ sd_notify() may be called
+ by a service to notify the service manager about
+ state changes. It can be used to send arbitrary
+ information, encoded in an environment-block-like
+ string. Most importantly it can be used for start-up
+ completion notification.
If the unset_environment
parameter is non-zero, sd_notify()
@@ -98,91 +126,156 @@
READY=1
- Tells the init system
- that daemon startup is finished. This
- is only used by systemd if the service
- definition file has Type=notify
- set. The passed argument is a boolean
- "1" or "0". Since there is little
+ Tells the service
+ manager that service startup is
+ finished. This is only used by systemd
+ if the service definition file has
+ Type=notify set. Since there is little
value in signaling non-readiness, the
- only value daemons should send is
- "READY=1".
+ only value services should send is
+ READY=1
+ (i.e. READY=0 is
+ not defined).
+
+
+
+ RELOADING=1
+
+ Tells the service manager
+ that the service is reloading its
+ configuration. This is useful to allow
+ the service manager to track the service's
+ internal state, and present it to the
+ user. Note that a service that sends
+ this notification must also send a
+ READY=1
+ notification when it completed
+ reloading its
+ configuration.
+
+
+
+ STOPPING=1
+
+ Tells the service manager
+ that the service is beginning its
+ shutdown. This is useful to allow the
+ service manager to track the service's
+ internal state, and present it to the
+ user.
STATUS=...
Passes a single-line
- status string back to the init system
- that describes the daemon state. This
+ UTF-8 status string back to the service manager
+ that describes the service state. This
is free-form and can be used for
various purposes: general state
feedback, fsck-like programs could
pass completion percentages and
failing programs could pass a human
readable error message. Example:
- "STATUS=Completed 66% of file system
- check..."
+ STATUS=Completed 66% of file
+ system
+ check...
ERRNO=...
- If a daemon fails, the
+ If a service fails, the
errno-style error code, formatted as
- string. Example: "ERRNO=2" for
+ string. Example: ERRNO=2 for
ENOENT.
BUSERROR=...
- If a daemon fails, the
+ If a service fails, the
D-Bus error-style error code. Example:
- "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
+ BUSERROR=org.freedesktop.DBus.Error.TimedOut
MAINPID=...
- The main pid of the
- daemon, in case the init system did
+ The main process ID (PID) of the
+ service, in case the service manager did
not fork off the process
itself. Example:
- "MAINPID=4711"
+ MAINPID=4711
WATCHDOG=1
- Tells systemd to
+ Tells the service manager to
update the watchdog timestamp. This is
the keep-alive ping that services need
to issue in regular intervals if
WatchdogSec= is
enabled for it. See
systemd.service5
- for details. It is recommended to send
- this message if the
- $WATCHDOG_PID
- environment variable has been set to
- the PID of the service process, in
- every half the time interval that is
- specified in the
- $WATCHDOG_USEC
- environment variable. See
+ for information how to enable this
+ functionality and
sd_watchdog_enabled3
- for details.
+ for the details of how the service can
+ check if the the watchdog is enabled.
+
+
+
+
+ FDSTORE=1
+
+ Stores additional file
+ descriptors in the service
+ manager. File descriptors sent this
+ way will be maintained per-service by
+ the service manager and be passed
+ again using the usual file descriptor
+ passing logic on the next invocation
+ of the service (see
+ sd_listen_fds3). This
+ is useful for implementing service
+ restart schemes where services
+ serialize their state to
+ /run, push their
+ file descriptors to the system
+ manager, and are then restarted,
+ retrieving their state again via
+ socket passing and
+ /run. Note that
+ the service manager will accept
+ messages for a service only if
+ FileDescriptorStoreMax=
+ is set to non-zero for it (defaults to
+ zero). See
+ systemd.service5
+ for details. Multiple arrays of file
+ descriptors may be sent in separate
+ messages, in which case the arrays are
+ combined. Note that the service
+ manager removes duplicate file
+ descriptors before passing them to the
+ service. Use
+ sd_pid_notify_with_fds()
+ to send messages with
+ FDSTORE=1, see
+ below.
+
+
It is recommended to prefix variable names that
- are not shown in the list above with
- X_ to avoid namespace
- clashes.
+ are not listed above with X_ to
+ avoid namespace clashes.
Note that systemd will accept status data sent
- from a daemon only if the
+ from a service only if the
NotifyAccess= option is correctly
set in the service definition file. See
systemd.service5
@@ -192,6 +285,36 @@
sd_notify() but takes a
printf()-like format string plus
arguments.
+
+ sd_pid_notify() and
+ sd_pid_notifyf() are similar to
+ sd_notify() and
+ sd_notifyf() but take a process
+ ID (PID) to use as originating PID for the message as
+ first argument. This is useful to send notification
+ messages on behalf of other processes, provided the
+ appropriate privileges are available. If the PID
+ argument is specified as 0 the process ID of the
+ calling process is used, in which case the calls are
+ fully equivalent to sd_notify()
+ and sd_notifyf().
+
+ sd_pid_notify_with_fds() is
+ similar to sd_pid_notify() but
+ takes an additional array of file descriptors. These
+ file descriptors are sent along the notification
+ message to the service manager. This is particularly
+ useful for sending FDSTORE=1
+ messages, as described above. The additional arguments
+ are a pointer to the file descriptor array plus the
+ number of file descriptors in the array. If the number
+ of file descriptors is passed as 0, the call is fully
+ equivalent to sd_pid_notify(),
+ i.e. no file descriptors are passed. Note that sending
+ file descriptors to the service manager on messages
+ that do not expect them (i.e. without
+ FDSTORE=1) they are immediately
+ closed on reception.
@@ -211,10 +334,7 @@
Notes
- These APIs are implemented as a shared library,
- which can be compiled and linked to with the
- libsystemd pkg-config1
- file.
+
Internally, these functions send a single
datagram with the state string as payload to the
@@ -224,7 +344,7 @@
$NOTIFY_SOCKET is @, the string is
understood as Linux abstract namespace socket. The
datagram is accompanied by the process credentials of
- the sending daemon, using SCM_CREDENTIALS.
+ the sending service, using SCM_CREDENTIALS.
@@ -234,7 +354,7 @@
$NOTIFY_SOCKET
- Set by the init system
+ Set by the service manager
for supervised processes for status
and start-up completion
notification. This environment variable
@@ -251,9 +371,9 @@
Start-up Notification
- When a daemon finished starting up, it
+ When a service finished starting up, it
might issue the following call to notify
- the init system:
+ the service manager:
sd_notify(0, "READY=1");
@@ -261,7 +381,7 @@
Extended Start-up Notification
- A daemon could send the following after
+ A service could send the following after
completing initialization:
sd_notifyf(0, "READY=1\n"
@@ -273,13 +393,25 @@
Error Cause Notification
- A daemon could send the following shortly before exiting, on failure
+ A service could send the following shortly before exiting, on failure:
sd_notifyf(0, "STATUS=Failed to start up: %s\n"
"ERRNO=%i",
strerror(errno),
errno);
+
+
+ Store a File Descriptor in the Service Manager
+
+ To store an open file descriptor in the
+ service manager, in order to continue
+ operation after a service restart without
+ losing state use
+ FDSTORE=1:
+
+ sd_pid_notify_with_fds(0, 0, "FDSTORE=1", &fd, 1);
+