ipython: Can I provide input to a shell command

Question

Can I execute a shell command that requires input in ipython and/or an ipython notebook?

When I execute such a command, I see it's prompt, but no apparent way to provide it with input from my keyboard.

An example could be an rsync command to a remote server (thus requiring a password). There are no doubt dangers security-wise here - these are somewhat reduced in my case as I'm running on localhost.

Answer 1

Reposting as an answer, with a bit more detail:

No, it's a long standing issue that's really difficult to resolve: github.com/ipython/ipython/issues/514

The issue is roughly that our architecture can't tell when a process is waiting for input, so it doesn't know to prompt the user for input.

You may be able to use pexpect and raw_input to simulate this for specific programs. I.e. if you say what the prompt looks like, it spots that in the output, and asks the user for input to send back to the process. E.g. for Python:

import pexpect
p = pexpect.spawn('python')
while True:
    try:
        p.expect('\n>>> ')
        print(p.before)
        p.sendline(raw_input('>>> '))
    except pexpect.EOF:
        break

I've just given this a brief test - it works, but it's fairly rough. The concept could be improved.

Answer 2

Sadly, no.

I couldn't find documentation on this, so I went source-diving. The ipython code that actually performs that transformation is https://github.com/ipython/ipython/blob/master/IPython/core/inputtransformer.py#L208 , specifically:

def _tr_system(line_info):
    "Translate lines escaped with: !"
    cmd = line_info.line.lstrip().lstrip(ESC_SHELL)
    return '%sget_ipython().system(%r)' % (line_info.pre, cmd)

which, in other words, invokes the underlying shell with everything following the !.

ipython is probably not what you want -- check out this answer for a Python alternate to include in scripts.