Linux process monitoring refers to the strategy of using a local agent that runs as a daemon, or as a cron job which polls the state of a process.
This can be as simple as to check that there exists a process with some specific numeric ID, or very complex checks to ensure that the status is not deadlocked, and configurable checks for resource usage.
Some popular Packages[]
monit god mon heartbeat-HA
Introduction[]
Typically, linux processing monitoring is used to either raise an alert about the error condition, or to run a remediation utility, such as a bash script or repair tool.
Process monitoring tools are often paired with more generalized alerting and monitoring tools such as nagios, zabbix, or ticketing tools like rt3.
monit[]
monit is a tool that supports a simple and robust configuration language, and simple http interface and scope for integration with other tools.
There is an commercial product called http://mmonit.com/
heartbeat-HA[]
this is a more complex product, which is part of a clustering suite of tools.