iLAMP

Advanced Bash-Scripting Guide
Very nice for shell script. It solves my trim string problem with easy command.
No awk/gsub required or sed .
look this
[root@localhost tools]# aa="hello world "
[root@localhost tools]# cc=lq
[root@localhost tools]# bb=${aa//" "/""}
[root@localhost tools]# echo $bb$cc
helloworldlq