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Learning Linux Shell Scripting. - Second Edition

You're reading from  Learning Linux Shell Scripting. - Second Edition

Product type Book
Published in May 2018
Publisher Packt
ISBN-13 9781788993197
Pages 332 pages
Edition 2nd Edition
Languages
Author (1):
Ganesh Sanjiv Naik Ganesh Sanjiv Naik
Profile icon Ganesh Sanjiv Naik

Table of Contents (17) Chapters

Preface 1. Getting Started and Working with Shell Scripting 2. Drilling Deep into Process Management, Job Control, and Automation 3. Using Text Processing and Filters in Your Scripts 4. Working with Commands 5. Exploring Expressions and Variables 6. Neat Tricks with Shell Scripting 7. Performing Arithmetic Operations in Shell Scripts 8. Automating Decision-Making in Scripts 9. Automating Repetitive Tasks 10. Working with Functions 11. Using Advanced Functionality in Scripts 12. System Startup and Customizing a Linux System 13. Pattern Matching and Regular Expressions with sed and awk 14. Taking Backup and Embedding Other Languages in Shell Scripts 15. Database Administration Using Shell Scripts 16. Other Books You May Enjoy

Returning information from functions

You have learned to pass command-line parameters to functions. Similarly, the function can return integers as a return value. Normally, functions return either TRUE or FALSE. In certain cases, the function can return integer values, such as 5 or 10, as well.

The syntax is:

    return N
  

When the function calls the command return, the function exits with the value specified by N.

If the function does not call the command return, then the exit status returned is
that of the last command executed in the function. If what we need is the status
of the last command executed in the function, then we need not return any value from the function. This is illustrated in the following script, function_14.sh:

#!/bin/bash 
is_user_root() { [ $(id -u) -eq 0 ]; } 
is_user_root && echo "You are root user, you can go ahead." 
|| echo "...
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