Random password generator using /dev/urandom

$ cat /dev/urandom| tr -dc 'a-zA-Z0-9' | fold -w 8| head -n 4

$ cat /dev/urandom| tr -dc 'a-zA-Z0-9-_!@#$%^&*()_+{}|:<>?='|fold -w 8| head -n 4

#from http://blog.colovirt.com/2009/01/07/linux-generating-strong-passwords-using-randomurandom/