Difference between Python's os.system and Perl's system command

[Gribouillis]

r' is not some magical operator that would apply to abitrary expressions. Instead, r'...' is a special kind of literal string where the \ character is taken literaly instead of being used as an escape character. Thus you can write

the_command = r"a dot exe file with 3 options"
subprocess.call (the_command, shell = True)

Most of the time however, shell=True is superfluous and/or detrimental and it is better to split the command in a list of arguments

import shlex
the_command = shlex.split(r"a dot exe file with 3 options")
subprocess.call (the_command)