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

Answer 1

Here-document works if your passwd doesn't support --stdin and you don't want to (or can't) use chpasswd for some reason.

Example:

#!/usr/bin/env bash

username="user"
password="pass"

passwd ${username} << EOD
${password}
${password}
EOD

Tested under Arch Linux. This passwd is an element of shadow-utils and installed from the core/filesystem package, which you usually have by default since the package is required by core/base.

Answer 2

Sometimes it is useful to set a password which nobody knows. This seems to work:

tr -dc A-Za-z0-9 < /dev/urandom | head -c44 | passwd --stdin $user

Answer 3

Nowadays, you can use this command:

echo "user:pass" | chpasswd

Answer 4

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 5

Tested this on a CentOS VMWare image that I keep around for this sort of thing. Note that you probably want to avoid putting passwords as command-line arguments, because anybody on the entire machine can read them out of 'ps -ef'.

That said, this will work:

user="$1"
password="$2"
adduser $user
echo $password | passwd --stdin $user

Answer 6

I stumbled upon the same problem and for some reason the --stdin option was not available on the version of passwd I was using (shipped in Ubuntu 14.04).

If any of you happen to experience the same issue, you can work it around as I did, by using the chpasswd command like this:

echo "<user>:<password>" | chpasswd