File system navigation. Changing directory

[GregoireLeGros]

Using Python 2.7. I want to navigate filesystem on a raspberry pi Linux box with pygame module. I am developing on a windows box in eclipse because it is quicker. Using a gamepad, and the XYAB buttons, I want to move around the filesystem and operate on the files. I am having trouble changing directory in order to do this. I understand there is a different paradigm in Linux as opposed to windows but I am finding this confusing.

import pygame, sys, os,subprocess
from subprocess import call
from pygame.locals import * # This module contains various constants used by Pygame


global p    #position in file_list
global n    #counter
global s    #size of file_list
global folder_cwd
global file_list


n=0
s=4
p=0

os.chdir("d:\\test\sub_1")
folder_cwd=os.getcwd()
file_list=os.listdir(os.getcwd())
s=len(file_list)


A = 0
B = 1
X = 2
Y = 3
     
def finish():
    ''' Self explanatory '''
    pygame.quit()
    sys.exit(0)
    
def input(events):
    ''' Function to handle events, particularly quitting the program '''
    global file_name
    global p    #position in the file_list
    global n    #counter
    global file_list
    global folder_cwd
    file_list=os.listdir(os.getcwd())
    s=len(file_list)
    
    for event in events:
        if event.type == JOYBUTTONDOWN: #using joystick buttons to navigate the filesystem
            button=event.button
            if(button==6):
                finish()    #quit()
            #print button
            folder_cwd=os.getcwd()
            file_list=os.listdir(os.getcwd())
            s=len(file_list)
            
            if(button==Y):  #cycling through the files in the current directoty
                n+=1    #moving to next file
                p=n%s
                file_name=file_list[p]
                if (os.path.isdir(file_name)):
                    print "This is a folder so we can change to it using the B button : ",file_name   
                
                print "This is a file : ",file_name
                    
                 
            if(button==A):  #cycling through the files in the current directoty
                n+=-1
                p=abs(n%s)
                file_name=file_list[p] 
                if (os.path.isdir(file_name)):
                    print "This is a folder so we can change to it using the B button : ",file_name
                print "This is a file : ",file_name
                
                    
                                  
            if(button==B):
                try:
                    new_folder=os.path.abspath(file_name)
                    print "os.path.basename : ",os.path.basename(file_name)
                    print "os.path.abspath : ",os.path.abspath(file_name)
                    print "os.getcwd() BEFORE CHANGE IS : ",os.getcwd()
                    
                    if os.path.isdir(new_folder):
                        print new_folder,"is a folder"
                        os.chdir(new_folder)
                        print "folder_getcwd IS : ",os.getcwd()
                        print "file_list is :",os.listdir(os.getcwd())  #DOESN'T PRINT THE FILE LIST
                    else:
                        print "Path doent exist"
                    
                except:
                    pass
                                
          
                    
pygame.init()
  
# Enable joystick support
pygame.joystick.init()

# Detect if joystick is available
joysticks = pygame.joystick.get_count()
for i in range(joysticks):
        joystick = pygame.joystick.Joystick(i)
        joystick.init()

# The game loop
while True:
    input(pygame.event.get())
    

On pressing button B with a folder as the current 'file_name' there is no output from the line

print "file_list is :",os.listdir(os.getcwd())

I understand python 3 makes this kind of thing easier.