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Mastering Bash

You're reading from   Mastering Bash A Step-by-Step Guide to working with Bash Programming and Shell Scripting

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Product type Paperback
Published in Jun 2017
Publisher Packt
ISBN-13 9781784396879
Length 502 pages
Edition 1st Edition
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Author (1):
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Giorgio Zarrelli Giorgio Zarrelli
Author Profile Icon Giorgio Zarrelli
Giorgio Zarrelli
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Table of Contents (15) Chapters Close

Preface 1. Let's Start Programming 2. Operators FREE CHAPTER 3. Testing 4. Quoting and Escaping 5. Menus, Arrays, and Functions 6. Iterations 7. Plug into the Real World 8. We Want to Chat 9. Subshells, Signals, and Job Controls 10. Lets Make a Process Chat 11. Living as a Daemon 12. Remote Connections over SSH 13. Its Time for a Timer 14. Time for Safety

Subshells, Signals, and Job Controls

Whatever we have seen so far was pretty straightforward. We launched a script that executed some commands, instances, variables, and made something out of it, that is all--one command after the other, one instruction piled on the previous one. This is what we would call a serial execution, one command after the other just like domino tiles: the first coming in and the first being processed; and this brings to mind the concept of the FIFO queue, First In First Out.

What if we wanted to process more than one instruction at a time? Well, we cannot do this and it would not be incorrect: a CPU is a serial device and it can process only one instruction at a time. What we use to give us the taste of multitasking is having the CPU switching between an instruction and the other really fast. So, instead of completely processing an instruction before...

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