Book Image

Mastering Linux Shell Scripting

By : Andrew Mallett
Book Image

Mastering Linux Shell Scripting

By: Andrew Mallett

Overview of this book

Shell scripting is a quick method to prototype a complex application or a problem by automating tasks when working on Linux-based systems. Using both simple one-line commands and command sequences complex problems can be solved with ease, from text processing to backing up sysadmin tools. In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Get to grips with the fundamentals of creating and running a script in normal mode, and in debug mode. Learn about various conditional statements' code snippets, and realize the power of repetition and loops in your shell script. Implement functions and edit files using the Stream Editor, script in Perl, program in Python – as well as complete coverage of other scripting languages to ensure you can choose the best tool for your project.
Table of Contents (21 chapters)
Mastering Linux Shell Scripting
About the Author
About the Reviewer

Limiting the number of entered characters

We do not need functionality in the scripts we have used so far, but we may need to ask users to hit any key to continue. At the moment, we have set it up in such a way that the variable is not populated until we hit the Enter key. Users have to hit Enter to continue. If we use the -n option followed by an integer, we can specify the characters to accept before continuing, we will set 1 in this case. Take a look at the following code extract:

read -p "May I ask your name: " name
echo "Hello $name"
read -n1 -p "Press any key to exit"
exit 0

Now, the script will pause after displaying the name until we press any key; literally, we can press any key before continuing, as we accept just 1 key stroke. Whereas, earlier we were required to leave the default behavior in place, as we could not know how long a entered name would be. We have to wait for the user to hit Enter.


Note that we add an additional echo here to ensure that a new line...