I have learned Java, C++, python. But recently I need to write some bash script.
Is there any book for learning bash script? Not bash command.
The Linux Documentation Project has a VERY nice BASH guide online. They call it the "Advanced Bash-Scripting Guide," but I think it is appropriate for beginners. This is my recommendation. http://tldp.org/LDP/abs/html/
In general, BashGuide is preferred for the beginner and it's very short - only 90 pages!