How to change password using script

#OUTFILE=out.xml prefix='EDSAD150' password="asdf1234" pass=$(perl -e 'print crypt($ARGV, "asdf1234")' $password) for i in {01..02};do usname=$prefix""$i yes $pass | yppasswd $usname done I want to change the password of the users but when I run this script I have to give the server password every time because I am usingyppasswd command . But when I used passwd command the NIS files won't change.