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

CHAPTER3

Automated Event Notification

To solve problems proactively, early warning is essential. In this chapter we are going to look at some techniques of getting the word out by automating the notification when a system event occurs. When we write monitoring shell scripts and there is a failure, success, or request, we need a method of getting a message to the right people. There are really three main strategies of notification in shell scripts. The first is to send an email directly to the user. We can also send an alphanumeric page by email to the user for immediate notification to a cell phone or pager. The third is to send a text page by dialing a modem to the service provider. We are mainly going to look at the first two methods, but we will also list some good software products that will send text pages by dialing the modem and transferring the message to the cellular/pager provider.

In some shops email is so restricted that you have to use a little trick or two to get around some of the restrictions. We will cover some of these situations, too.

Basics of Automating Event Notification

In a shell script there are times when you want to send an automated notification. As an example, if you are monitoring filesystems and your script finds that one of the filesystems has exceeded the maximum threshold, then most likely you want to be informed of this situation. I always like an email notification when the backups complete every night — not just when there is a backup error, ...