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 a command in the background

There are some situations in which you might want to continue running other commands as you wait for another one to complete, to run more than one job in parallel. You can arrange for a command to run in the background by ending it with a single ampersand (&) control operator.

You can try this out by issuing a sleep command in the background. The sleep built-in Bash command accepts a number of seconds to wait as an argument. If you enter such a command without the &, Bash won't accept further commands until the command exits:

$ sleep 10
# Ten seconds pass... $

However, if you add the & terminator to start the job in the background, the behavior is different: you get a job control number and a process ID, and you are returned immediately to your prompt:

$ sleep 10 &
[1] 435

You can continue running other commands as normal...