How can I set a users password in linux from a python script?

Question

I'm trying to automate the setup of SFTP access. This script is running as a user with sudo permissions and no password.

I can create a user like so:

>>> import subprocess
>>> process = subprocess.Popen(['sudo', 'useradd', 'test'], shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
>>> process.communicate()
('', '')

Next I need to set the user's password, but I can't figure out how. Here's what I've tried.

>>> process = subprocess.Popen(['sudo', 'chpasswd'], shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
>>> process.communicate('test:password')

In my python program it has no effect, in the interactive interpreter it locks up after the first line.

What's the best way to do this?

I'm running python 2.6 on Ubuntu lucid.

Answer 1

The documentation for communicate says that you'll need to add stdin=PIPE if you're sending data to standard input via the communicate parameter:

http://docs.python.org/release/2.6/library/subprocess.html#subprocess.Popen.communicate

I appreciate this is just skeleton code, but here are another couple of other small comments, in case they are of use:

• If you're not interested in the output of the useradd command other than whether it failed or not, you might be better off using subprocess.check_call which will raise an exception if the command returns non-zero.
• In the second case, you should check whether process.returncode is 0 after your call to communicate('test:password')