Today the Advanced Bash-Scripting guide has been updated: http://www.tldp.org/LDP/abs/html/
Changelog: “Many bugs were fixed. Additionally, there is a great deal of new material. Editing was done for increased consistency. Two new example scripts were added.”
This is not a book that everyone will want to read, but for those wanting to know more about scripting or those with bash scripting knowledge its a must. Its available in a couple of formats for your reading pleasure.