Book Image

Mastering Linux Shell Scripting - Second Edition

By : Mokhtar Ebrahim, Andrew Mallett
5 (1)
Book Image

Mastering Linux Shell Scripting - Second Edition

5 (1)
By: Mokhtar Ebrahim, Andrew Mallett

Overview of this book

In this book, you’ll discover everything you need to know to master shell scripting and make informed choices about the elements you employ. Grab your favorite editor and start writing your best Bash scripts step by step. 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. You will also learn to write complex shell scripts. This book will also deep dive into file system administration, directories, and system administration like networking, process management, user authentications, and package installation and regular expressions. Towards the end of the book, you will learn how to use Python as a BASH Scripting alternative. By the end of this book, you will know shell scripts at the snap of your fingers and will be able to automate and communicate with your system with keyboard expressions.
Table of Contents (17 chapters)

Counting arguments

As previously mentioned, the script name is the first argument at index 0 of the array. So, if we try to count the arguments, then the count should always be at the very least 1. In other words, if we have not supplied arguments, the argument count will be 1. To count the items in an array, we can use the len() function.

If we edit the script to include a new line we will see this work, as follows:

#!/usr/bin/python3
import sys
print("Hello " + sys.argv[1])
print( "length is: " + str(len(sys.argv)) )

Executing the code as we have earlier, we can see that we have supplied two arguments—the script name and then the string Mokhtar:

If we try and have a single print statement to print the output and the number of arguments, then it will produce an error because we can't concatenate integers with strings. The length value is an integer...