The Linux Documentation Project

• Bash Programming — Introduction HOW-TO, Mike G, The Linux Documentation Project.
• Bash Guide for Beginners, Machtelt Garrels, The Linux Documentation Project.
• Advanced Bash-Scripting Guide, Mendel Cooper, The Linux Documentation Project

Of Robust Shell Scripts

• Writing Robust Shell Scripts, David Pashley.com
• Tips for Robust Bash Scripts, Alex Collins.com
• What are the rules to write robust shell scripts?, StackOverflow.com

Shell Internals

• Order of Shell Command Line Processing, Ian D. Allen
• Filenames and Pathnames in Shell: How to do it Correctly, David A. Wheeler

Pitfalls and Mistakes

• Bash: Beginner Mistakes, Bash-Hackers.org
• Bash Pitfalls, Wooledge.org. 46 and more common errors that Bash programmers make.
• Shell Mistakes, GreenEnd.org.uk. There are a number of easy mistakes to make when using Bash.
• Bash FAQ, Wooledge.org. 111 FAQs with answers.

Various

• Examples of Small Bash Scripts, Hlevkin.com. A set of small scripts, which demonstrate some features of bash programming.
• Hints and Tips for General Shell Script Programming, ics.griffith.edu.au