from subpiper import subpiper

def my_stdout_callback(line: str):
    # do whatever you like with stdout lines
    print(f'STDOUT: {line}')

def my_stderr_callback(line: str):
    # do whatever you like with stderr lines
    print(f'STDERR: {line}')

# add some path to the PATH for your subprocess
my_additional_path_list = [r'c:\important_location']

# call subpiper to take care everyting in blocking mode
retcode, *_ = subpiper(
    cmd='echo magic',
    stdout_callback=my_stdout_callback,
    stderr_callback=my_stderr_callback,
    add_path_list=my_additional_path_list
)
# blocks until subprocess finishes

# you can get the buffered outputs as list of strings as well, besides the callbacks:
retcode, so, se = subpiper(
    cmd='echo magic',
    stdout_callback=my_stdout_callback,
    stderr_callback=my_stderr_callback,
    add_path_list=my_additional_path_list
)
print('STD out captured:', '\n'.join(so))
print('STD err captured:', '\n'.join(se))

from subpiper import subpiper

def process_done(retcode: int):
    print(f'Subprocess finished with return code: {retcode}')

# call subpiper to take care everyting in non-blocking mode
subpiper(
    cmd='echo magic',
    stdout_callback=my_stdout_callback,
    stderr_callback=my_stderr_callback,
    add_path_list=my_additional_path_list,
    finished_callback=process_done
)
# do your other stuff
...
# when the subprocess finishes, your process_done callback will be invoked.