shell-runner.py

import re

def indent(string: str, indenter="    ", num_indents=1) -> str:
    for i in range(num_indents):
        string = indenter + string # first line
        string = string.replace('\n', '\n'+indenter) # all other lines
    return string

def remove_empty_lines(string: str) -> str:
    return re.sub(r"\n{2,}", '\n', string)

class ShellRunner:
    """
    spawn this with a shell command, then you have access to stdout, stderr, exit code,
    along with a boolean of whether or not the command was a success (exit code 0)
    and if you use str(your_shell_runner), you get a formatted report of all the above
    """
    def __init__(self, command, timeout_s):
        try:
            process = subprocess.run(
                command,
                capture_output=True,
                shell=True,
                timeout=timeout_s
            )
            # process.std* returns a bytes object, convert to string
            self.shell_output = remove_empty_lines(str(process.stdout, 'UTF-8'))
            self.shell_error = remove_empty_lines(str(process.stderr, 'UTF-8'))
            self.exit_code = process.returncode
        except subprocess.TimeoutExpired as timeout_err:
            try:
                self.shell_output = remove_empty_lines(str(timeout_err.stdout, 'UTF-8'))
            except TypeError:
                self.shell_output = ''
            try:
                self.shell_error = remove_empty_lines(str(timeout_err.stderr, 'UTF-8'))
            except TypeError:
                self.shell_error = f'timeout after {timeout_s} seconds!'
            self.exit_code = 1

        self.success = self.exit_code == 0
        self.command_report = '\n'.join([
            "command:",
            indent(command),
            f"exit code: {self.exit_code}",
            '',
            "stdout:",
            indent(self.shell_output),
            '',
            "stderr:",
            indent(self.shell_error),
        ])
    def __str__(self):
        return self.command_report