Linux® Command Line and Shell Scripting Bible

Chapter 13. Script Control

IN THIS CHAPTER

• Revisiting signals

• Hiding in the background

• Running with no console

• Being nice

• Running like clockwork

• Starting at the beginning

As you start building more advanced scripts, you'll probably start to wonder how to run and control them on your Linux system. So far in this book, the only way we've run scripts is directly from the command line interface in real-time mode. This isn't the only way to run scripts in Linux. There are quite a few other options available for running your shell scripts on Linux systems. This chapter examines different ways you can use to get your scripts started. Also, sometimes you might run into the problem of a script that gets stuck in a loop and you need to figure out how to get it to stop without having to turn off your Linux system. This chapter examines the different ways you can control how and when your shell script runs on your system.

Handling Signals

Linux uses signals to communicate with processes running on the system. Chapter 4 described the different Linux signals and how the Linux system uses these signals to stop, start, and kill processes. You can also use these signals to control the operation of your shell scripts by programming your shell script to perform commands when it receives specific signals from the Linux system.

Linux signals revisited

There are over 30 Linux signals that can be generated by the system and applications. Table 13-1 lists the most common Linux system signals that you'll run across ...