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NAME
     watchdog - Mac OS X Server service monitoring daemon

SYNOPSIS
     watchdog [-d | -n | -x] [-r] [-f file]
     watchdog [-h | -v]

DESCRIPTION
watchdog is an (AT&T) init-like process that launches,
monitors, and relaunches critical services when they
terminate.  watchdog improves reliability of the system
by maintaining these critical services in a uniform
manner without resorting to service-specific monitors
(which would impact system performance).

OS X Server man page

pwd:respawn:/usr/sbin/PasswordService -n
PSM:respawn:/usr/sbin/PrintServiceMonitor -x
mm:off:/usr/sbin/MacintoshManagementServer -x
postfix:respawn:/usr/libexec/postfix/master
cyrus:off:/usr/bin/cyrus/bin/master

#  Added for backup exec agent
backupexec:respawn:/etc/bkupexec/agent.be
   -c /etc/bkupexec/agent.cfg

Example /etc/watchdog.conf file

Watchdog also helps restart the server if its
operating system becomes unresponsive (a "hang").
On computers that support automatic restart, this
option can be activated in the Energy Saver pane of
System Preferences. Once activated, Watchdog
periodically resets the computer's Power Management
Unit (PMU) timer. If this timer expires (which happens
if the system hangs), the PMU forces a restart.

Apple developer documentation