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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

Product type Paperback

Published in Jun 2017

Publisher Packt

ISBN-13 9781784396879

Length 502 pages

Edition 1st Edition

Languages

Bash

Tools

Bash

Concepts

Shell Scripting

Author (1):

Zarrelli

View More author details

Table of Contents (22) Chapters

Title Page

Credits

About the Author

About the Reviewer

www.PacktPub.com

Customer Feedback

Preface

1. Let's Start Programming FREE CHAPTER

2. Operators

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

1. Use in Real World Application

DEMO

So, how could we turn one of our into a daemon? One first attempt could be using&. The trailing ampersand is a Bash built-in which instructs the shell to run the command in the background inside a subshell. Once the command is executed, the shell does not wait for it to finish but returns a code 0, which means successful, and proceeds further in any other commands that are to be executed:

zarrelli:~$ ls -lah & ps -jf
[1] 13704
total 48K
drwxr-xr-x 4 zarrelli zarrelli 4.0K Apr 12 14:12 .
drwxr-xr-x 4 zarrelli zarrelli 4.0K Apr 12 19:37 ..
-rw-r--r-- 1 zarrelli zarrelli 11 Apr 10 09:20 controller
-rwxr--r-- 1 zarrelli zarrelli 121 Apr 11 18:30 coproc.sh
-rwxr--r-- 1 zarrelli zarrelli 961 Apr 11 12:19 environment.sh
-rwxr--r-- 1 zarrelli zarrelli 382 Apr 11 10:08 looping.sh
-rw-r--r-- 1 zarrelli zarrelli 0 Apr 10 09:20 myfile.txt
-rw-r--r-- 1 zarrelli zarrelli 122 Apr 10 09:20 myfile.txt.tgz
-rw-r--r-- 1 zarrelli zarrelli 367 Apr 12 14:12 my_index.html
prw-r--r-- 1 zarrelli zarrelli...

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Authors (1)

Zarrelli

Zarrelli

Giorgio Zarrelli is a passionate GNU/Linux system administrator and Debian user, but has worked over the years with Windows, Mac, and OpenBSD, writing scripts, programming, installing and configuring services--whatever is required from an IT guy. He started tinkering seriously with servers back in his university days, when he took part in the Computational Philosophy Laboratory and was introduced to the Prolog language. As a young guy, he had fun being paid for playing games and write about them in video game magazines. Then he grew up and worked as an IT journalist and Nagios architect, and recently moved over to the threat intelligence field, where a lot of interesting stuff is happening nowadays. Over the years, he has worked for start-ups and well-established companies, among them In3 incubator and Onebip as a database and systems administrator, IBM as QRadar support, and Anomali as CSO, trying to find the best ways to help companies make the best out of IT. Giorgio has written several books in Italian on different topics related to IT, from Windows security to Linux system administration, covering MySQL DB administration and Bash scripting.

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