There is no subshell, assignments before a command are only in effect for that command.

Simple-Command-Expansion:
I used this trick in the extracting floating numbers from variable using bash's builtin string chopping thread.

Thanks for explaining inc. link and sorry for not appreciating your use of it at http://www.linuxquestions.org/questi...24#post3609924. Vague memories of reading about it are coming to mind along with deciding not to use it because it did not match legibility aspirations. All the same it's a valid technique and I should know about it, even if I choose not to use it.

Just for fun (and the upcoming obfuscated bash competition):

Sorry ntubski, I have given you the wrong info. There should be no dot between the numerals and the song names.

01-01 song with spaces in filename.mp3
01-02 song with spaces in filename.mp3


etc...

I have changed the script to (ls *-*\ *.mp3),but it didn't work.
Can you explain how does your "cut -d. -f2" work?

BTW, Files I want to rename are scattered across different folders. for instance, they are all in different subfolders. How can I move them one directory up in order to rename them in batch?

etc

EDIT: I have figured it out:
in working directory, type

"cut -d. -f2" assumes that the song name is separated from the numerals by dots, so of course it doesn't work. It extracts the text between the 1st and 2nd dots.

Here's a version that assumes the song name is the part that comes after the numbers and dashes. I had to rearrange the loop a bit to handle whitespace.