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

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Join Date: Apr 2008

Posts: 3

Reputation: punmeister is an unknown quantity at this point

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punmeister punmeister is offline

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

Nov 26th, 2008

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

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
#!/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"
#!/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"

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Join Date: Jul 2008

Posts: 1,009

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jlm699

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

Nov 26th, 2008

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:

 Help with Code Tags 
 python Syntax (Toggle Plain Text) 
#!/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()
#!/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()