Utility to execute simple command-line programs through python, for use in python shell scripts.

process.py

#!/usr/bin/env python3
"""
Utility to execute "simple" (non-daemon) command-line programs through python,
for use in python shell scripts.
WARNING: As this script can trigger any command-line process,
please be careful not to ruin your system.
"""

from typing import List, Union
import os, shlex, sys
from subprocess import PIPE, Popen


env = os.environ.copy()


class Process:
    """Encapsulate useful values returned by subprocess execution, for use in command-line scripts."""

    cmd: str
    out: str = ""
    err: str = ""
    returncode: int

    def __init__(self, args: Union[str, List[str]], print=True):
        if type(args) == str:
            self.cmd = interpret_cmd_from_string(args)
        else:
            self.cmd = args
        pipes = Popen(self.cmd, stdout=PIPE, stderr=PIPE, env=env)
        stdout, stderr = pipes.communicate()
        if stderr:
            self.err = stderr.decode()
            if print:
                sys.stderr.write(self.err)
        if stdout:
            self.out = stdout.decode()
            if print:
                sys.stdout.write(self.out)
        if print:
            sys.stdout.flush()
        self.returncode = pipes.returncode

    @property
    def ok(self) -> bool:
        return self.returncode == 0

    @property
    def lines(self) -> List[str]:
        s = self.err
        if self.out:
            s = self.out
        return [line for line in s.split("\n") if line != ""]


def interpret_cmd_from_string(args: str) -> List[str]:
    """Given a command string, return a subprocess-compatible argument list.."""
    if not args:
        raise Exception("No command args provided.")
    if "~" in args:
        args = args.replace("~", os.path.expanduser("~"))
    args = shlex.split(args)
    return args


# To run on the command line:
if __name__ == "__main__":
    args = " ".join(sys.argv[1:])
    Process(args)