Shell Programming and Scripting

Can someone explain what is happening line by line in this script, particularly after the do statement. The script works, it renames all the files in my directory that has a date in the file name. But I would like to know more about it.

#!/bin/bash
newdate=12-10-1995
for file in *[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]*
do
mv $file ${file%[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9].*}$newdate${file#*[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]}
done

It tries to rename any file with 2-2-4 digit date in the name and replace that date with a new date, but it contains an error as the dot should not be there.
It use parameter expansion to accomplish this.

Code:

newdate=12-10-1995
for file in *[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]*
do
  mv "$file" "${file%[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]*}$newdate${file#*[0-9][0-9]-[0-9][0-9]-[0-9][0-9][0-9][0-9]}"
done

And it is better to put double quotes there.

what does $file " "${file% -- do and $newdate${file#* -- whats this.

It cuts of part of the string, see the link.

Ok, thanks again.

Unless the target filename has a real dot there.

Good point