Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By : Richard Blum, Christine Bresnahan
Book Image

Linux Command Line and Shell Scripting Bible - Third Edition

By: Richard Blum, Christine Bresnahan

Overview of this book

The Linux command line enables you to type specific shell commands directly into the system to manipulate files and query system resources. Command line statements can be combined into short programs called shell scripts, a practice increasing in popularity due to its usefulness in automation. Linux is a robust system with tremendous potential, and Linux Command Line and Shell Scripting Bible opens the door to new possibilities. Linux Command Line and Shell Scripting Bible is your essential Linux guide. It contains new functional examples that are fully updated to align with the latest Linux features. Beginning with command line fundamentals, the book moves into shell scripting and shows you the practical application of commands in automating frequently performed functions. This book is a complete guide providing detailed instruction and expert advice working within this aspect of Linux. Whether used as a tutorial or as a quick reference, this book contains information that every Linux user should know.
Table of Contents (34 chapters)
2
Part I: The Linux Command Line
13
Part II: Shell Scripting Basics
20
Part III: Advanced Shell Scripting
28
Part IV: Creating Practical Scripts
32
End User License Agreement

Working through a Practical Example

The advanced gawk features come in handy if you have to handle data values in a data file, such as tabulating sales figures or calculating bowling scores. When you work with data files, the key is to first group related data records together and then perform any calculations required on the related data.

For example, let's work with a data file that contains the bowling scores from a game between two teams, each with two players:

$ cat scores.txt
Rich Blum,team1,100,115,95
Barbara Blum,team1,110,115,100
Christine Bresnahan,team2,120,115,118
Tim Bresnahan,team2,125,112,116
$

Each player has scores from three separate games in the data file, and each player is identified by a team name in the second column. Here's the shell script to sort the data for each team and calculate the totals and averages:

$ cat bowling.sh
#!/bin/bash
for team in $(gawk –F, '{print $2}' scores.txt | uniq)
do
   gawk –v team=$team 'BEGIN...