passwd command in shell script

I am making a shell script that automatically create users, but 开发者_StackOverflow中文版I cannot think of how to use passwd command within my shell script, how should I use it with shell script? --stdin option doesn't work for me

Try expect(1).

Some implementations of passwd have the --stdin flag which you can use like so:

passwd --stdin user <<<"SoMePasSw0rd"

Works for me on Debian

echo -e "$NEWPASS\n$NEWPASS" | passwd $USER