Book Image

Bash Quick Start Guide

By : Tom Ryder
Book Image

Bash Quick Start Guide

By: Tom Ryder

Overview of this book

Bash and shell script programming is central to using Linux, but it has many peculiar properties that are hard to understand and unfamiliar to many programmers, with a lot of misleading and even risky information online. Bash Quick Start Guide tackles these problems head on, and shows you the best practices of shell script programming. This book teaches effective shell script programming with Bash, and is ideal for people who may have used its command line but never really learned it in depth. This book will show you how even simple programming constructs in the shell can speed up and automate any kind of daily command-line work. For people who need to use the command line regularly in their daily work, this book provides practical advice for using the command-line shell beyond merely typing or copy-pasting commands into the shell. Readers will learn techniques suitable for automating processes and controlling processes, on both servers and workstations, whether for single command lines or long and complex scripts. The book even includes information on configuring your own shell environment to suit your workflow, and provides a running start for interpreting Bash scripts written by others.
Table of Contents (10 chapters)

Running commands in sequence

You can send an interactive command line with more than one simple command in it, separating them with a semicolon, one of several possible control operators. Bash will then execute the commands in sequence, waiting for each simple command to finish before it starts the next one. For example, we could write the following command line and issue it in an interactive Bash session:

$ cd ; ls -a ; mkdir New
Running cd on its own like this, with no directory target argument, is a shortcut to take you to your home directory. It's the same as typing cd ~ or cd -- "$HOME".

For this command line, note that even if one of the commands fails, Bash will still keep running the next command. To demonstrate this, we can write a command line to include a command that we expect to fail, such as the rmdir call here:

$ cd ; rmdir ~/nonexistent ; echo &apos...