execute(Command, Args, Trace, Trace):-
    process_create(Command, Args, [stdout(pipe(In))]),
    report_command_output(Trace, In),
    close(In).

report_command_output(Trace, In):-
    peek_char(In, Char),
    (Char = end_of_file ->
        true
    ;
        read_line(In, Line),
        trace_message(Trace, '~w', [Line]),
        report_command_output(Trace, In)
    ).

read_line(In, Line):-
    read_line(In, [], Line).

read_line(In, Cs, Line):-
    get_char(In, Char),
    (Char = '\n' ->
        reverse(Cs, Cs1),
        atom_chars(Line, Cs1)
    ;
        read_line(In, [Char|Cs], Line)
    ).