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)

Choosing between functions and scripts

Having established the difference between functions and scripts, how can we know which is the best to use in which situation?

The choice can be subtle, but here's a basic guide to start:

  • If you want your command only to be limited to an interactive shell, for example to override interactive behavior, add options to a command, or other shortcuts, use a function. Filesystem programs are useable outside the Bash shell, while functions are limited to the Bash process only.
  • If you want your command to affect a running shell process, such as to change your current shell directory, or to read or set shell variables, use a function. Filesystem programs cannot change properties of your current shell process.
  • In all other situations, use a script as a filesystem program in a bindir specified in $PATH. This script will then be callable by the...