January 2021
Intermediate to advanced
832 pages
18h 3m
English
Content preview from Linux Command Line and Shell Scripting Bible, 4th Edition
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.
CHAPTER 16Script Control
As you start building advanced scripts, you'll probably 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 execute scripts in Linux. Quite a few options are available for running your shell scripts. There are also options for controlling your scripts. Various control methods include sending signals to your script, modifying a script's priority, and switching the run mode while a script is running. This chapter examines the various ways you can control your shell scripts.
Handling Signals
Linux uses signals to communicate with processes running on the system. Chapter 4, “More Bash Shell Commands,” described the different Linux signals and how the Linux system uses these signals to stop, start, and kill processes. You can control the operation of your shell script by programming the script to perform certain commands when it receives specific signals.
Signaling the Bash shell
There are more than 30 Linux signals that can be generated by the system and applications. Table 16-1 lists the most common Linux system signals that you'll run across in your shell script writing.
TABLE 16-1 Linux Signals
| Signal | Value | Description |
|---|---|---|
1 |
SIGHUP |
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.