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)

Respecting and applying the user's configuration

Never assume a user's choice of line-text editor ($EDITOR), visual-text editor ($VISUAL), shell ($SHELL), or web browser ($BROWSER). Instead, fall back to sensible defaults if these values are not set, using the :- form of parameter expansion:

read -p 'Now editing your configuration file (press ENTER): '
"${VISUAL:-vi}" -- "$HOME"/.myscriptrc

The preceding script will wait for an Enter key press (well, a line entry, technically). It then starts the user's choice of visual-text editor if it's set, or defaults to vi if it's not, which should be installed on most Unix-like systems. In some circumstances, such as a script for use by beginners, a more sensible default choice might be nano. Consider carefully what your script's users might expect to happen; avoid...