rename directories
With this one you can rename directories. Their names are stored in a1.txt (one per line). If you want to change the names of hundred directories, then such a script makes sense.
open (ERSTE, "a1.txt") || die "file not found\n"; @fileinput1 = <ERSTE>; close (ERSTE); $a1 = @fileinput1[0]; rename ("no1", "$a1") or die $!;