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

Pythonic arguments

We should know by now that we will want to be able to pass command-line arguments to Python and we can do this using the argv array similar to Perl. However, we are more like bash, with Python we combine the program name into the array with the other arguments. Python also uses lowercase instead of uppercase in the object name.

  • The argv array is a part of the sys object

  • sys.argv[0] is the script name

  • sys.argv[1] is the first argument supplied to the script

  • sys.argv[2] is the second supplied argument and so on

  • The argument count will always be at least 1, so, keep this in mind when checking for supplied arguments

Supplying arguments

If we create the $HOME/bin/ file we can see this in action. The file should be created as follows and made executable:

import sys
print("Hello " + sys.argv[1])

If we run the script with a supplied argument, we should be able to see something similar to the following screenshot:

Our code is still quite clean and simple; however...