Nagios, 2nd Edition

25.4 Implementing Timeouts

To implement a hard timeout, the function alarm() is available in C, Perl, and other programming languages, which normally calls the system functon of the same name (see man 2 alarm). For the Perl alarm() function, the timeout is specified in seconds:

# ... GetOptions ...
alarm($timeout);
# ... core code ...
alarm(0);
# ... end

The alarm($timeout) call starts the alarm function, the argument 0 for the second call stops it again. The first call should be used before time-intensive processing steps, in network-based plugins before opening sockets, and similar situations where a long delay may occur. A good place is after the command line has been processed via GetOptions.

At the end of the plugin it is recommended that you ...