Mastering UNIX® Shell Scripting: Bash, Bourne, and Korn Shell Scripting for Programmers, System Administrators, and UNIX Gurus, Second Edition

CHAPTER16

Monitoring Processes and Applications

The most critical part of any business is ensuring that applications continue to run without error. In this chapter, we are going to look at several techniques for monitoring applications and critical processes that the applications rely on. The problem with trying to write this chapter is that there are so many applications in the corporate world that the techniques to monitor them vary widely.

From the lowest level, we can ping the machine to see if it is up. A ping, though, is not an operating system response, but rather a machine response that only confirms that the network adapter is configured. Then again, if the machine is in the DMZ, ping is probably disabled at the router. At a higher level, we can look at the processes that are required for the application to run properly, but this too does not completely confirm, 100 percent, that the application is working properly. The only way to ensure the application is working properly is to interact with the application. As an example, if we have a database that the application requires we can do a simple SQL query to ensure that the database is working properly. For interactive applications, we can try to use a here document or an expect script to log in to the application, or server, and maybe even perform a small task. Applications work differently, so solutions to ensure that the application is up and running properly will vary widely.

We are going to look at monitoring local ...