# 7_filesystem.py
# JAH 090402
#
# Useful functions for interacting with the file system

# copying a file
import shutil
shutil.copy('output.txt', 'output2.txt')

# renaming a file
import os
os.rename('output2.txt', 'output3.txt')

# getting a list of files in the current directory
files = os.listdir('.')
print "Files in the current directory: " + str(files)

# file paths on Windows:
### absolute path
filepath = "C:\\Python25\\blah\\file.txt"
print "absolute path (Windows): " + filepath
### relative path
filepath = "directory\\subdirectory\\file.txt"
print "relative path (Windows): " + filepath

# file paths on Unix/Linux/OS X
### absolute path
filepath = "/home/john/blah/file.txt"
print "absolute path (Linux/OS X): " + filepath
### relative path
filepath = "directory/subdirectory/file.txt"
print "relative path (Linux/OS X): " + filepath

# creating a file path in a platform-independent way
### relative path
filepath= "directory" + os.sep + "subdirectory" + os.sep + "file.txt"
print "relative path (platform-independent) #1: " + filepath

# is equivalent to
directoryPath = ["directory", "subdirectory", "file.txt"]
filepath = os.sep.join(directoryPath)
print "relative path (platform-independent) #2: " + filepath

# getting the absolute path of the current directory
currentDirectory = os.path.abspath(".")
print "currentDirectory #1: " + currentDirectory

# is equivalent to
currentDirectory = os.path.abspath(os.path.curdir)
print "currentDirectory #2: " + currentDirectory

# is equivalent to
currentDirectory = os.getcwd()
print "currentDirectory #3: " + currentDirectory

# determine if a file/directory exists
if os.path.exists('output.txt'):
   print "output.txt exists!"
else:
   print "output.txt doesn't exist"

# create a directory if it doesn't already exist
newDirectory = 'temp'
if not os.path.exists(newDirectory):
   print 'Making a new directory called: ' + newDirectory
   os.mkdir(newDirectory)

# see the following links for lots of other useful file system related functions:
# http://docs.python.org/library/os.html 
# http://docs.python.org/library/os.path.html 
# http://docs.python.org/library/shutil.html