Using the passwd command from within a shell script

Question

I'm writing a shell script to automatically add a new user and update their password. I don't know how to get passwd to read from the shell script instead of interactively prompting me for the new password. My code is below.

adduser $1 passwd $1 $2 $2

Answer 1

The only solution works on Ubuntu 12.04:

echo -e "new_password\nnew_password" | (passwd user) 

But the second option only works when I change from:

echo "password:name" | chpasswd 

To:

echo "user:password" | chpasswd 

See explanations in original post: Changing password via a script

Answer 2

from "man 1 passwd":

   --stdin           This option is used to indicate that passwd should read the new           password from standard input, which can be a pipe. 

So in your case

adduser "$1" echo "$2" | passwd "$1" --stdin 

[Update] a few issues were brought up in the comments:

Your passwd command may not have a --stdin option: use the chpasswd utility instead, as suggested by ashawley.

If you use a shell other than bash, "echo" might not be a builtin command, and the shell will call /bin/echo. This is insecure because the password will show up in the process table and can be seen with tools like ps.

In this case, you should use another scripting language. Here is an example in Perl:

#!/usr/bin/perl -w open my $pipe, '|chpasswd' or die "can't open pipe: $!"; print {$pipe} "$username:$password"; close $pipe