Python optparse and spaces in an argument

Question

When using optparse i want to get the whole string after an option, but I only get part of it up to the first space.

e.g.:

python myprog.py --executable python someOtherProg.py

What I get in 'executable' is just 'python'.

Is it possible to parse such lines using optparse or do you have to use argparse to do it?

€: I have already tried enclosing it in "s. But after digging further into the code I found out that the subprocess invocation can't handle the argument.

The string with the commandline gets crammed into a list 'args'.

args = [self.getExecutable()] + self.getArgs().split()

It's like

"[python D:\\\workspace\\\myprog\\\src\\\myprog.py]"

That gives me the System can't find file exception. When I use

args[0]

it works. But I loose the arguments to the executable.

The subprocess module builds a cmdline from a list if it does not get a string in the first place, so I can't explain that behavior at the moment.

Answer 1

You can enclose them in quotes to make them work with the existing code.

python myprog.py --executable "python someOtherProg.py"

Is it possible to parse such lines using optparse or do you have to use argparse to do it?

I don't know if/how you can do it with optparse as I haven't really worked with optparse.

I can however help you out with argparse. Here is a quick example:

#!/usr/bin/python
import argparse, sys

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description = 'Demonstration of Argparse.')
    parser.add_argument('-e', '--executable', nargs = '+', help = 'List of executables')
    args = parser.parse_args(sys.argv[1:])
    print args.executable

And usage:

manoj@maruti:~$ python myprog.py --executable python someOtherProg.py
['python', 'someOtherProg.py']

I'd also recommend switching from optparse to argparse. Optparse is deprecated since 2.7.

Answer 2

I've found another good alternative shlex - A lexical analyzer class for simple shell-like syntaxes.

Source link: How to parse a command line with regular expressions?

>>> import shlex
>>> shlex.split('"param 1" param2 "param 3"')
['param 1', 'param2', 'param 3']
>>> shlex.split('"param 1" param2 "param 3"')
Traceback (most recent call last):
    [...]
ValueError: No closing quotation
>>> shlex.split('"param 1" param2 "param 3\\""')
['param 1', 'param2', 'param 3"']