Help with finding out if a program exists in os path entries
 

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"

Re: Help with finding out if a program exists in os path entries
 

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()

Re: Help with finding out if a program exists in os path entries
 

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?