Tag Archives: pty.fork

Scripting ssh and git securely with Python

Some programs such as SSH ask for password and key passphrase via TTY (rather than STDIN), which is not supported by Python’s subprocess.Popen() call – the otherwise recommended, convenient way or running programs in a separate process.

This issue also arises when using SSH and PKI keys with git, to secure communications with a git server without an username and password.

This example illustrates use of pty.fork() from Python stdlib to support communications with a child process via a tty (a pty, actually).

There’s also some more explanations on how pty.fork() works, from Stack Overflow. Furthermore, Paul Mikesell has written an extensive article on scripting SSH with Python.