Hey hey!
I'm trying to write a script that finds out if a given program name exists in the OS environments PATH variable (cross plathform). Thing is, I get a NameError, it's probably a simple error, but I've struggling with it the last hour.

Any help would be appreciated

#!/usr/bin/env python
import os
import os.path

"""
If the folder the program  resides in is not added to the path the
program will naturally not run, since the executing environment have
no idea where it resides.
"""

if findprogram("mathlab")[0] == 1:
    print "W00t"
else:
    print "Oh noes!"

def findprogram(program):
    path = os.environ['PATH']
    paths = path.split(os.pathsep)
    for d in paths:
        if os.path.isdir(d):
            fullpath = os.path.join(d, program)
            if sys.platform[:3] == 'win':
                for ext in '.exe', '.bat':
                    if os.path.isfile(fullpath + ext):
                      return 1, program_path
            else:
                if os.path.isfile(fullpath):
                    return 1, program_path
    return 0, program + " command not found"

You're calling the function findprogram before defining it.... if you simply rearrange your code so that the def findprogram(program): block is first, you'll solve the problem. You'll then find that you forgot to import sys And then you'll find that you're trying to use some variable called program_path when instead you might have wanted fullpath

A good way to avoid this is to not ever let your code hang out in the ether like that... commonplace is to place your code all into functions, and have a main() function to call them... Here's a pretty commonly used method:

#!/usr/bin/python
import #whatever needs imported

def # Define some functions

def main():
    # Do anything that needs done here
    # Call functions, etc...

if __name__ == '__main__':
    main()

Crap, I see that now. I can't belive I'd forgotton how C-like python was. Is there any way you can define prototypes in python like C?

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