not the most efficient one, since i am new to perl. but enough for your work#!/usr/bin/perl @list = `ls test/*.b`; foreach $a (@list){ chomp($a); $com = "mv ".$a." $a.c"; exec($com); } assume your dir is "test" your old extension is .b , new one is .c I hope to see perl experts to show me the greatest power of perl by doing same job using many and much more efficient ways :)