X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsd_notify.xml;h=2bf3383c0db38793eccfcbecdbf86796b06603dc;hp=7c1d982d855e4f37654ce653f9fd600bac7cdcfe;hb=a2e0337875addaf08225fbf9b231435ba12a88b5;hpb=ad678a066b4ba5d8914dd7d5a4093572841205cf
diff --git a/man/sd_notify.xml b/man/sd_notify.xml
index 7c1d982d8..2bf3383c0 100644
--- a/man/sd_notify.xml
+++ b/man/sd_notify.xml
@@ -8,20 +8,21 @@
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
+ Lesser General Public License for more details.
- You should have received a copy of the GNU General Public License
+ You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see .
-->
-
+
sd_notify
@@ -45,12 +46,15 @@
sd_notify
sd_notifyf
- Notify init system 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
- #include "sd-daemon.h"
+ #include <systemd/sd-daemon.h>
int sd_notify
@@ -64,22 +68,46 @@
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()
+ parameter is non-zero, sd_notify()
will unset the $NOTIFY_SOCKET
- environment variable before returning (regardless
+ environment variable before returning (regardless of
whether the function call itself succeeded or
not). Further calls to
sd_notify() will then fail, but
@@ -87,7 +115,7 @@
processes.
The state parameter
- should contain an newline-seperated list of variable
+ should contain a newline-separated list of variable
assignments, similar in style to an environment
block. A trailing newline is implied if none is
specified. The string may contain any kind of variable
@@ -98,77 +126,195 @@
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
- value in signalling non-readiness, the
- only value daemons should send is
- "READY=1".
+ 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 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 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 information how to enable this
+ functionality and
+ sd_watchdog_enabled3
+ 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 seperate
+ 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
for details.
sd_notifyf() is similar to
- sd_notifyf() but takes a
+ 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.
@@ -178,63 +324,37 @@
errno-style error code. If
$NOTIFY_SOCKET was not set and
hence no status data could be sent, 0 is returned. If
- the status was sent these functions return with a
+ the status was sent, these functions return with a
positive return value. In order to support both, init
systems that implement this scheme and those which
- don't, it is generally recommended to ignore the return
+ do not, it is generally recommended to ignore the return
value of this call.
Notes
- These functions are provided by the reference
- implementation of APIs for new-style daemons and
- distributed with the systemd package. The algorithms
- they implement are simple, and can easily be
- reimplemented in daemons if it is important to support
- this interface without using the reference
- implementation.
+
Internally, these functions send a single
datagram with the state string as payload to the
- AF_UNIX socket referenced in the
+ AF_UNIX socket referenced in the
$NOTIFY_SOCKET environment
variable. If the first character of
- $NOTIFY_SOCKET is @ the string is
+ $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.
-
- For details about the algorithm check the
- liberally licensed reference implementation sources:
-
- resp.
-
- sd_notify() and
- sd_notifyf() are implemented in
- the reference implementation's drop-in
- sd-daemon.c and
- sd-daemon.h files. It is
- recommended that applications consuming these APIs
- copy the implementation into their source tree. For
- more details about the reference implementation see
- sd_daemon7
-
- If -DDISABLE_SYSTEMD is set during compilation
- this function will always return 0 and otherwise
- become a NOP.
+ the sending service, using SCM_CREDENTIALS.
Environment
-
+
$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"
@@ -273,22 +393,35 @@
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);
+
See Also
systemd1,
- sd_daemon7,
+ sd-daemon3,
daemon7,
- systemd.service5
+ systemd.service5,
+ sd_watchdog_enabled3