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

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Try expect(1).

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

passwd --stdin user <<<"SoMePasSw0rd"

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Works for me on Debian

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