Python run shell command shorthand

parallel_sh.py

import subprocess
import sys

from asyncio import Future
from contextlib import contextmanager


@contextmanager
def ParallelSh():
    """
    Context manager that provides a function to run processes in parallel. All
    processes have terminated when the context manager exists. An exception is
    raised if one (or more) processes failed. Resulting stdout is provided via
    a Future.
    """
    procs = []
    def run(cmd, input=None, **kwargs):
        if input is not None:
            kwargs['stdin'] = subprocess.PIPE
        proc = subprocess.Popen(cmd, shell=True,
                                stdout=subprocess.PIPE, stderr=sys.stderr,
                                encoding='UTF-8', **kwargs)
        if input is not None:
            proc.stdin.write(input)
            proc.stdin.close()
            proc.stdin = None
        proc.stdout_future = Future()
        procs.append(proc)
        return proc.stdout_future
    yield run
    for proc in procs:
        proc.wait()
        proc.stdout_future.set_result(proc.communicate()[0])
    for proc in procs:
        if proc.returncode:
            raise subprocess.CalledProcessError(proc.returncode, proc.args,
                                                output=proc.stdout_future.result())

# Basic usage:
with ParallelSh() as sh:
    date1 = sh('date')   # sh returns a Future containing stdout
    sh('sleep 1')
    date2 = sh('date')
print(date1.result())
print(date2.result())

# Provide some input:
with ParallelSh() as sh:
    wc = sh('wc -l', input='foo\nbar\n')
print(wc.result())

# stderr is forwarded:
with ParallelSh() as sh:
    sh('echo some error 1 >&2')
    sh('echo some error 2 >&2')

# Exception on error, after all processes have terminated
try:
    with ParallelSh() as sh:
        date = sh('date')
        sh('false')
except Exception as e:
    print(f'date still valid: {date.result()}')
    print(f'Exception caught: {e}')

sh.py

import sys
import subprocess


def sh(cmd, **kwargs):
    return subprocess.run(cmd, shell=True, check=True,
                          stdout=subprocess.PIPE, stderr=sys.stderr,
                          encoding='UTF-8', **kwargs).stdout


# Basic usage:
print(sh('date'))

# Provide some input:
print(sh('wc -l', input='foo\nbar\n'))

# stderr is forwarded:
sh('echo some error >&2')

# Exception on error
try:
    sh('false')
except Exception as e:
    print(f'Exception caught: {e}')