Simplest way to run external command line app with parameters?

[snippsat]

A advice subprocess.run should be used with all cases it can handle.
Subprocess Doc

The recommended approach to invoking subprocesses is to use the run() function for all use cases it can handle.
For more advanced use cases, the underlying Popen interface can be used directly.

Can also use capture_output=True,and no need top use args.insert as see f-string dos this fine.

import subprocess

output_file = "%03d.jpg"
input_file = "input.doc"
executable_path = r"C:\app.exe"
command_line = f"{executable_path} command -a 50 -o {output_file} {input_file}"
args = command_line.split()
result = subprocess.run(args, encoding='utf-8', capture_output=True)
print(result.stdout)