Nagios Plugin check_uptime

check_uptime - check how long the system has been running

[/etc/nrpe.d/check_uptime]
command[check_uptime]=/usr/lib/nagios/plugins/check_uptime
command[check_uptime_notify]=/usr/lib/nagios/plugins/check_uptime --critical 30:

Usage note

In the example above, a notification will be sent by Nagios when the uptime of the monitored server will be less than 30 minutes. This will catch, for instance, an unexpected reboot of a servers caused by a non-maskable interrupt (a signal of a non-recoverable hardware error).

A note on the implementation of "check_uptime" provided by nagios-plugins 2.0+

This new Nagios plugin is based on the POSIX function clock_gettime() associated with the clock monotonic option (CLOCK_MONOTONIC). According to the POSIX specifications "the value returned by clock_gettime() represents the amount of time (in seconds and nanoseconds) since an unspecified point in the past (for example, system start-time, or the Epoch)". The (recent) Linux kernels returns a value that is somehow related to the system start-time but can be different from the output of the command uptime (procps), or the first value of /proc/uptime.

$ /usr/bin/uptime
18:45:00 up  8:46,  7 users,  load average: 0.67, 1.79, 2.49

$ awk '{printf("%02d:%02d\n",($1/60/60%24),($1/60%60))}' /proc/uptime
08:46

$ ./clock_monotonic
4 hours 37 min

(On OpenBSD 5.0, the clock monotonic function returns the same value as uptime, which is confirming this behaviour is platform dependent).

The implementation followed by nagios-plugins-linux is compatible with uptime and /proc/uptime.

This plugin checks how long the system has been running.
Copyright (C) 2010,2012-2014 Davide Madrisan <[email protected]>

Usage:
  check_uptime [OPTION]

Options:
  -m, --clock-monotonic  use the monotonic clock for retrieving the time
  -w, --warning PERCENT   warning threshold
  -c, --critical PERCENT   critical threshold
  -h, --help      display this help and exit
  -V, --version   output version information and exit

Examples:
  check_uptime
  check_uptime --critical 15: --warning 30:
  check_uptime --clock-monotonic -c 15: -w 30:

See the Nagios Developer Guidelines for range format:
<https://nagios-plugins.org/doc/guidelines.html#THRESHOLDFORMAT>

Example of output

uptime OK: 23 hours 56 min | uptime=1436

Performance data

uptime (in minutes)