Example 1. Start-up Notification
When a service finished starting up, it might issue the following
call to notify the service manager:
sd_notify(0, "READY=1");
Example 2. Extended Start-up Notification
A service could send the following after completing
initialization:
sd_notifyf(0, "READY=1\n"
"STATUS=Processing requests...\n"
"MAINPID=%lu",
(unsigned long) getpid());
Example 3. Error Cause Notification
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);
Example 4. 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\nFDNAME=foobar", &fd, 1);
Example 5. Eliminating race conditions
When the client sending the notifications is not spawned by the
service manager, it may exit too quickly and the service manager
may fail to attribute them correctly to the unit. To prevent such
races, use sd_notify_barrier() to synchronize against reception
of all notifications sent before this call is made.
sd_notify(0, "READY=1");
/* set timeout to 5 seconds */
sd_notify_barrier(0, 5 * 1000000);
