Your Own Linux..! recently published a multi-part series on Unix/Linux shell scripting, that would be useful to anyone desiring to write a bash script. The articles are:
Introduction – Linux / Unix Shell (Bash) Scripting
Bash Scripting Variables – Environment and Special Shell Variables
Bash Scripting – Arithmetic, Logical, Relational and Bitwise Operators
Bash Scripting – Arrays with Examples
Bash Scripting Conditionals – if-then-else, if-elif-else, Nested if-else
Bash Scripting – ‘case’ Statement
Bash Scripting – ‘select’ Loop and ‘select-case’ Statement
That’s the complete list as of the publication date of this post (EDIT: Plus a couple of late additions). If you want to check to see if any have been added since then, go here.