Table Of ContentMastering Python Scripting for
System Administrators
Write scripts and automate them for real-world administration
tasks using Python
Ganesh Sanjiv Naik
BIRMINGHAM - MUMBAI
Mastering Python Scripting for System
Administrators
Copyright © 2019 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form
or by any means, without the prior written permission of the publisher, except in the case of brief quotations
embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented.
However, the information contained in this book is sold without warranty, either express or implied. Neither the
author, nor Packt Publishing or its dealers and distributors, will be held liable for any damages caused or alleged to
have been caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all of the companies and products
mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy
of this information.
Commissioning Editor: Vijin Boricha
Acquisition Editor: Shrilekha Inani
Content Development Editor: Sharon Raj
Technical Editor: Prashant Chaudhari
Copy Editor: Safis Editing
Project Coordinator: Drashti Panchal
Proofreader: Safis Editing
Indexer: Rekha Nair
Graphics: Tom Scaria
Production Coordinator: Jyoti Chauhan
First published: January 2019
Production reference: 1240119
Published by Packt Publishing Ltd.
Livery Place
35 Livery Street
Birmingham
B3 2PB, UK.
ISBN 978-1-78913-322-6
www.packtpub.com
I wish to dedicate this book to my Gurudev, His Holiness Dr. Jayant Balaji Athavale. I wish to
express gratitude for his guidance on how to become a good human being, a good professional,
and a seeker on the path of spiritual progress.
mapt.io
Mapt is an online digital library that gives you full access to over 5,000 books and videos, as
well as industry leading tools to help you plan your personal development and advance
your career. For more information, please visit our website.
Why subscribe?
Spend less time learning and more time coding with practical eBooks and Videos
from over 4,000 industry professionals
Improve your learning with Skill Plans built especially for you
Get a free eBook or video every month
Mapt is fully searchable
Copy and paste, print, and bookmark content
Packt.com
Did you know that Packt offers eBook versions of every book published, with PDF and
ePub files available? You can upgrade to the eBook version at www.packt.com and as a print
book customer, you are entitled to a discount on the eBook copy. Get in touch with us at
[email protected] for more details.
At www.packt.com, you can also read a collection of free technical articles, sign up for a
range of free newsletters, and receive exclusive discounts and offers on Packt books and
eBooks.
Contributors
About the author
Ganesh Sanjiv Naik is an author, consultant, and corporate trainer in the fields of AI, data
science, machine learning, the Internet of Things (IoT), and embedded Linux in relation to
product development. He has more than 20 years of professional experience in information
technology. Ganesh has a passion and a deep desire for teaching. He has trained 2,000+
engineers in Linux and Android product development. He has worked as a corporate
trainer for the ISRO, Intel, GE, Samsung, Motorola, Penang Skill Development Center
(Malaysia), and various companies in Singapore, Malaysia, and India. He has started a
company called Levana Technologies, which works in AI, machine learning, and data
science, providing training, projects, and consultancy activities.
I want to thank my wife, Vishalakshi Naik, for providing valuable suggestions, support,
and continuous motivation. I also want to thank my colleagues, Mansi Joshi and Kalpesh
Patil, who helped me in editing and proofreading, and also provided feedback from a
technical perspective.
Big thanks to the entire team at Packt, especially Shrilekha Inani, Priyanka Deshpande,
and Sharon Raj, for providing me with motivating support throughout the book.
About the reviewers
Yogendra Sharma is a developer with experience in the architecture, design, and
development of scalable and distributed applications, with a core interest in microservices
and Spring. He is currently working as an IoT and cloud architect at Intelizign Engineering
Services Pvt, Pune. He also has hands-on experience in technologies such as AWS Cloud,
IoT, Python, J2SE, J2EE, Node.js, Angular, MongoDB, and Docker. He constantly explores
technical novelties, and he is open-minded and eager to learn about new technologies and
frameworks. He has reviewed several books and video courses published by Packt
Publishing.
Abhijeet Mote has a master's degree in computer application (MCA) from University of
Mumbai. He is an open source evangelist and works as a senior software engineer. He has
worked in multiple domains, including education, media, and IoT. His hobbies involve
work on open source projects, and he loves to give back to the open source community by
spreading knowledge of Python and other open source stacks. He conducts training
sessions for students, teachers, and enthusiastic developers, and he mentors students for
their final year projects. He has been invited to conferences, such as FOSSASIA 2018, and
PyGotham, for his contribution in teaching open source technology to enthusiastic
developers and underrepresented groups.
Packt is searching for authors like you
If you're interested in becoming an author for Packt, please visit authors.packtpub.com
and apply today. We have worked with thousands of developers and tech professionals,
just like you, to help them share their insight with the global tech community. You can
make a general application, apply for a specific hot topic that we are recruiting an author
for, or submit your own idea.
Table of Contents
Preface 1
Chapter 1: Python Scripting Overview 7
Technical requirements 8
Why Python? 8
Python syntax compared to other programming languages 8
Python installation 9
Installation on the Linux platform 9
Installation on the Windows platform 9
Installing and using pip to install packages 9
Installation on Mac 10
Installing Jupyter notebook 10
Installing and using the virtual environment 10
Installing Geany and PyCharm 11
Python interpreter 11
The difference between Python and Bash scripting 12
Starting the interactive console 12
Writing scripts with the Python interactive console 12
Multiple lines 13
Importing modules through the Python interpreter 14
Exiting the Python console 15
The keyboard shortcut 15
Using the quit() or exit() functions 15
Indentation and tabs 15
Variables 16
Creating and assigning values to variables 17
Numbers 18
Number type conversion 20
Strings 20
Concatenation (+) and repetition (*) 21
String slicing 22
Accessing values in strings 22
Updating strings 23
Escape characters 23
Special string operators 24
% string formatting operator 24
Triple quotes in Python 25
Strings are immutable 25
Understanding lists 26
Accessing values in lists 26
Table of Contents
Updating lists 27
Deleting list elements 27
Basic list operations 27
List operations 28
Indexing, slicing, and matrices 29
Tuples 29
Accessing values in tuples 30
Updating tuples 31
Deleting tuple elements 31
Basic tuple operations 31
Indexing, slicing, and matrices 32
max() and min() 32
Sets 33
Dictionaries 34
Parsing command-line arguments 35
Command-line arguments in Python 35
Sys.argv 35
Decision making 36
Python if statement syntax 36
Python if...else statement syntax 37
Python if...elif...else statement 37
Loops 38
for loop 38
The range() function 40
while loop 40
Iterators 42
Generators 42
How to create a generator in Python? 43
Functions 43
The return statement 44
Lambda functions 44
Modules 45
Importing modules 46
Summary 46
Questions 46
Further reading 47
Chapter 2: Debugging and Profiling Python Scripts 48
What is debugging? 48
Python debugging techniques 49
Error handling (exception handling) 49
Debuggers tools 51
The pdb debugger 51
Within an interpreter 52
From a command line 53
[ ii ]
Table of Contents
Within a Python script 54
Debugging basic program crashes 54
Profiling and timing programs 56
The cProfile module 56
timeit 57
Making programs run faster 58
Summary 58
Questions 58
Further reading 59
Chapter 3: Unit Testing - Introduction to the Unit Testing Framework 60
What is unittest? 60
Creating unit tests 61
Methods used in unit testing 62
Summary 64
Questions 65
Further reading 65
Chapter 4: Automating Regular Administrative Activities 66
Accepting input by redirection, pipe, and input files 66
Input by redirection 67
Input by pipe 68
Input by input file 69
Handling passwords at runtime in scripts 69
Executing external commands and getting their output 70
Capturing output using the subprocess module 71
Prompting for passwords during runtime and validation 72
Reading configuration files 74
Adding logging and warning code to scripts 76
Generating warnings 77
Putting limits on CPU and memory usage 78
Launching webbrowser 79
Using the os module for handling directory and files 79
Creating and deleting the directory 80
Examining the content of a filesystem 80
Making backups (with rsync) 81
Summary 83
Questions 83
Further reading 83
Chapter 5: Handling Files, Directories, and Data 84
Using the os module to work with directories 84
Get the working directory 85
Changing the directory 85
Listing files and directories 85
[ iii ]
