Bash Command Line and Shell Scripts Pocket Primer

285 Pages·2020·19.178 MB·English

by  Oswald Campesato (author)

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Oswald Campesato
MERCURY LEARNING AND INFORMATION
Dulles, Virginia
Boston, Massachusetts
New Delhi
Copyright © 2020 by Mercury Learning and inforMation LLC.
All rights reserved.
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Publisher: David Pallai
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O. Campesato. Bash Command Line and Shell Scripts Pocket Primer.
ISBN: 978-1-68392-504-0
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CONTENTS
Preface xv
Chapter 1: Introduction 1
What is Unix? 2
Available Shell Types 2
What is bash? 3
Getting help for Commands 4
bash
Navigating Around Directories 4
The Command 4
history
Listing Filenames with the Command 5
ls
Displaying Contents of Files 8
The Command 8
cat
The and Commands 9
head tail
The Pipe Symbol 10
The Command 11
fold
File Ownership: Owner, Group, and World 11
Hidden Files 12
Handling Problematic Filenames 13
Working with Environment Variables 13
The Command 13
env
Useful Environment Variables 14
Setting the Environment Variable 14
PATH
Specifying Aliases and Environment Variables 15
Finding Executable Files 16
The Command and the echo Command 17
printf
The Command 17
cut
viii • Bash Command Line and Shell Scripts
The echo Command and Whitespaces 18
Command Substitution (“backtick”) 20
The “pipe” Symbol and Multiple Commands 20
Using a Semicolon to Separate Commands 21
The Command 22
paste
Inserting Blank Lines with the Command 22
paste
A Simple Use Case with the Command 23
paste
A Simple Use Case with and Commands 24
cut paste
What about zsh? 25
Switching between bash and zsh 26
Configuring zsh 26
Summary 26
Chapter 2: Files and Directories 29
Create, Copy, Remove, and Move Files 29
Creating Text Files 29
Copying Files 30
Copy Files with Command Substitution 30
Deleting Files 31
Moving Files 32
The Command 32
ln
The basename, dirname, and file Commands 33
The Command 33
wc
The Command 34
cat
The Command and the Command 34
more less
The Command 35
head
The tail Command 36
Comparing File Contents 38
The Parts of a Filename 38
Working with File Permissions 39
The Command 40
chmod
Changing owner, permissions, and groups 40
The umask and ulimit Commands 41
Working with Directories 41
Absolute and Relative Directories 41
Absolute/Relative Pathnames 41
Creating Directories 42
Removing Directories 43
Navigating to Directories 43
Moving Directories 44
Using Quote Characters 44
Streams and Redirection Commands 45
Working with Metacharacters 46
Working with Character Classes 47
Contents • ix
MetaCharacters and Character Classes 48
Digits and Characters 48
Working with “^” and “\” and “!” 49
Filenames and Metacharacters 49
Summary 50
Chapter 3: Useful Commands 51
The join Command 52
The Command 52
fold
The Command 53
split
The Command 53
sort
The Command 56
uniq
How to Compare Files 56
The Command 57
od
The Command 57
tr
A Simple Use Case 60
The Command 61
find
The Command 62
tee
File Compression Commands 63
The command 63
tar
The Command 63
cpio
The gzip and gunzip Commands 64
The bunzip2 Command 64
The zip Command 65
Commands for zip Files and bz Files 65
Internal Field Separator (IFS) 65
Data From a Range of Columns in a Dataset 66
Working with Uneven Rows in Datasets 68
Summary 68
Chapter 4: Conditional Logic and Loops 71
Quick Overview of Operators in bash 71
Arithmetic Operations and Operators 72
The expr Command 72
Arithmetic Operators 73
Boolean and Numeric Operators 73
Compound Operators and Numeric Operators 74
Working with Variables 74
Assigning Values to Variables 75
The Command for User Input 76
read
Boolean Operators and String Operators 76
Compound Operators and String Operators 77
File Test Operators 78
Compound Operators and File Operators 79