I have came across many situations where a bunch of files with one filename extension has to be renamed to another extension. Here is the way to do it in bash.
We will rename a number of post script files to PDF files ( .ps to .pdf )
safeer@penguinpower:~/Documents$ ls
book0.ps book1.ps book2.ps book3.ps book4.ps
safeer@penguinpower:~/Documents$ for file in $(ls *.ps);
do
mv $file ${file/%.ps/.pdf};
done
safeer@penguinpower:~/Documents$ ls
book0.pdf book1.pdf book2.pdf book3.pdf book4.pdf
