Cameron Newham - Learning the bash Shell: Unix Shell Programming (In a Nutshell (OReilly))

Copyright 2009 O'Reilly Media, Inc.

shows you how to go about it.

bash is a backward-compatible evolutionary successor to the Bourne shell that includes most of the C shell's major advantages as well as features from the Korn shell and a few new features of its own. Features appropriated from the C shell include:

bash 's major new features include:

This book is designed to address casual UNIX and Linux users who are just above the "raw beginner" level. You should be familiar with the process of logging in, entering commands, and doing simple things with files. Although reviews concepts such as the tree-like file and directory scheme, you may find that it moves too quickly if you're a complete neophyte. In that case, we recommend the O'Reilly handbook, Learning the UNIX Operating System , by Jerry Peek, Grace Todino, and John Strang.

If you're an experienced user, you may wish to skip reveals a few subtle differences between the bash and C shells.

No matter what your level of experience is, you will undoubtedly learn many things in this book that will make you a more productive bash userfrom major features down to details at the "nook-and-cranny" level that you may not have been aware of.

If you are interested in shell programming (writing shell scripts and functions that automate everyday tasks or serve as system utilities), you should also find this book useful. However, we have deliberately avoided drawing a strong distinction between interactive shell use (entering commands during a login session) and shell programming. We see shell programming as a natural, inevitable outgrowth of increasing experience as a user.

Accordingly, each chapter depends on those previous to it, and although the first three chapters are oriented toward interactive use only, subsequent chapters describe interactive, user-oriented features in addition to programming concepts.

This book aims to show you that writing useful shell programs doesn't require a computing degree. Even if you are completely new to computing, there is no reason why you shouldn't be able to harness the power of bash within a short time.

Toward that end, we decided not to spend too much time on features of exclusive interest to low-level systems programmers. Concepts like file descriptors and special file types might only confuse the casual user, and anyway, we figure those of you who understand such things are smart enough to extrapolate the necessary information from our cursory discussions.