Delegator.py — Subprocesses for Humans 2.0

Delegator.py is a simple library for dealing with subprocesses, inspired by both envoy and pexpect (in fact, it depends on it!).

This module features two main functions delegator.run() and delegator.chain(). One runs commands, blocking or non-blocking, and the other runs a chain of commands, separated by the standard unix pipe operator: |.

Basic Usage

Basic run functionality:

>>> c = delegator.run('ls')
>>> print c.out
README.rst   delegator.py

>>> c = delegator.run('long-running-process', block=False)
>>> c.pid
35199
>>> c.block()
>>> c.return_code
0

Commands can be passed in as lists as well (e.g. ['ls', '-lrt']), for parameterization.

Basic chain functionality:

# Can also be called with ([['fortune'], ['cowsay']]).
# or, delegator.run('fortune').pipe('cowsay')

>>> c = delegator.chain('fortune | cowsay')
>>> print c.out
  _______________________________________
 / Our swords shall play the orators for \
 | us.                                   |
 |                                       |
 \ -- Christopher Marlowe                /
  ---------------------------------------
         \   ^__^
          \  (oo)\_______
             (__)\       )\/\
                 ||----w |
                 ||     ||

Expect functionality is built-in too, on non-blocking commands:

>>> c.expect('Password:')
>>> c.send('PASSWORD')
>>> c.block()

Other functions:

>>> c.kill()
>>> c.send('SIGTERM', signal=True)

# Only available when block=True, otherwise, use c.out.
>>> c.err
''

# Direct access to pipes.
>>> c.std_err
<open file '<fdopen>', mode 'rU' at 0x10a5351e0>

# Adjust environment variables for the command (existing will be overwritten).
>>> c = delegator.chain('env | grep NEWENV', env={'NEWENV': 'FOO_BAR'})
>>> c.out
NEWENV=FOO_BAR

Installation

$ pip install delegator.py

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