====== Python basic examples ======
===== Python processing file and directory =====
==== os package ====
  * Executing a shell command<code python>
os.system()</code>
  * Get the users environment <code python>
os.environ()</code>
  * Returns the current working directory<code python>
os.getcwd()</code>
  * Return a list of the entries in the directory given by path<code python>
os.listdir(path)</code>
  * Create a directory named path with numeric mode mode<code python>
os.mkdir(path)</code>
  * Recursive directory creation function<code python>
os.makedirs(path)</code>
  * Remove (delete) the file path<code python>
os.remove(path)</code>
  * Remove directories recursively<code python>
os.removedirs(path)</code>
  * Rename the file or directory src to dst<code python>
os.rename(src, dst)</code>
  * Remove (delete) the directory path<code python>
os.rmdir(path)</code> 

==== os.path basic functions ====
  * split:<code python>
import os
from urlparse import urlparse
 
filename = "E:\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi.html"

print "full filename", filename
print "using", os.name, "..."
print "split", "=>", os.path.split(filename)
print "splitdrive", "=>", os.path.splitdrive(filename)
print "splitext", "=>",os.path.splitext(filename)
print "splitunc", "=>",os.path.splitunc(filename)
</code>output:<code>
full filename E:\do-choi\do-choi-giay\the-hinh-chu-so-vua-hoc-vua-choi.html
using nt ...
split => ('E:\\do-choi\\do-choi-giay', 'the-hinh-chu-so-vua-hoc-vua-choi.html')
splitdrive => ('E:', '\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi.html')
splitext => ('E:\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi', '.html')
splitunc => ('', 'E:\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi.html')
</code>
  * using os.path to check what a filename represents<code python>
import os

FILES = (
    os.curdir,
    "/",
    "file",
    "/file",
    "samples",
    "samples/sample.jpg",
    "directory/file",
    "../directory/file",
    "/directory/file"
    )

for file in FILES:
    print file, "=>",
    if os.path.exists(file):
        print "EXISTS",
    if os.path.isabs(file):
        print "ISABS",
    if os.path.isdir(file):
        print "ISDIR",
    if os.path.isfile(file):
        print "ISFILE",
    if os.path.islink(file):
        print "ISLINK",
    if os.path.ismount(file):
        print "ISMOUNT",
    print
</code>output:<code>
. => EXISTS ISDIR
/ => EXISTS ISABS ISDIR ISMOUNT
file =>
/file => ISABS
samples => EXISTS ISDIR
samples/sample.jpg => EXISTS ISFILE
directory/file =>
../directory/file =>
/directory/file => ISABS
</code>

==== os.path custom examples ====
  * Using os.path to handle filename<code python>
import os
import re
 
filename = "my/little/pony.txt"
 
print "using", os.name, "..."
print "split", "=>", os.path.split(filename)
print "splitext", "=>", os.path.splitext(filename)
print "dirname", "=>", os.path.dirname(filename)
print "basename", "=>", os.path.basename(filename)
print "join", "=>", os.path.join(os.path.dirname(filename),
                                 os.path.basename(filename))
print "realpath", os.path.realpath(filename)
print "abspath", os.path.abspath(filename)
print "rename filename to ", re.sub(r'\.txt', '', filename) + '.html'</code> => output<code>
using nt ...
split => ('my/little', 'pony.txt')
splitext => ('my/little/pony', '.txt')
dirname => my/little
basename => pony.txt
join => my/little\pony.txt
realpath E:\backup\GoogleDrive\projects\python\my\little\pony.txt
abspath E:\backup\GoogleDrive\projects\python\my\little\pony.txt
rename filename to  my/little/pony.html
</code>
  * get normal path<code python>
import os
 
filename = "E:\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi.html"

print "full filename", filename
print "basename", os.path.basename(filename)
print "dirname", os.path.dirname(filename)
print "splitdrive", "=>", os.path.splitdrive(filename)
fullpathname = os.path.dirname(filename)
pathname = os.path.splitdrive(fullpathname)[1]
print "pathname = ", pathname
normalpath = pathname[1:]
print "normalpath = ", normalpath
</code>output:<code>
full filename E:\do-choi\do-choi-giay\the-hinh-chu-so-vua-hoc-vua-choi.html
basename the-hinh-chu-so-vua-hoc-vua-choi.html
dirname E:\do-choi\do-choi-giay
splitdrive => ('E:', '\\do-choi\\do-choi-giay\\the-hinh-chu-so-vua-hoc-vua-choi.html')
pathname =  \do-choi\do-choi-giay
normalpath =  do-choi\do-choi-giay
</code>
  * urlparse<code python>
import os
from urlparse import urlparse
 
url = "http://shop.babies.vn/do-choi/do-choi-giay/the-hinh-chu-so-vua-hoc-vua-choi.html"
o = urlparse(url)
print o
filename = o.path
print filename
print "split", "=>", os.path.split(filename)
print "splitext", "=>", os.path.splitext(filename)
print "dirname", "=>", os.path.dirname(filename)
print "basename", "=>", os.path.basename(filename)
print "join", "=>", os.path.join(os.path.dirname(filename),
                                 os.path.basename(filename))
print "realpath", os.path.realpath(filename)
print "abspath", os.path.abspath(filename)
</code>output:<code>
ParseResult(scheme='http', netloc='shop.babies.vn', path='/do-choi/do-choi-giay/the-hinh-chu-so-vua-hoc-vua-choi.html', params='', query='', fragment='')
/do-choi/do-choi-giay/the-hinh-chu-so-vua-hoc-vua-choi.html
split => ('/do-choi/do-choi-giay', 'the-hinh-chu-so-vua-hoc-vua-choi.html')
splitext => ('/do-choi/do-choi-giay/the-hinh-chu-so-vua-hoc-vua-choi', '.html')
dirname => /do-choi/do-choi-giay
basename => the-hinh-chu-so-vua-hoc-vua-choi.html
join => /do-choi/do-choi-giay\the-hinh-chu-so-vua-hoc-vua-choi.html
realpath E:\do-choi\do-choi-giay\the-hinh-chu-so-vua-hoc-vua-choi.html
abspath E:\do-choi\do-choi-giay\the-hinh-chu-so-vua-hoc-vua-choi.html
</code>
==== Get all files and directories in current directory ====
  * using os.path.walk list all file in current directory and all subdirectories<code python>
import os

def gotodir(arg, directory, files):
    for file in files:
        print file

os.path.walk(".", gotodir, "")
</code>Output<code>
.project
.pydevproject
conent.tpl
index.html
parser.py
test.py
</code>
  * using os.path.walk list all full filename in current directory and all subdirectories<code python>
import os
 
def gotodir(arg, directory, files):
    for file in files:
        fullfilename = os.path.join(directory,file)
        print fullfilename
 
os.path.walk(".", gotodir, "")
</code>
  * Find all files with extension ".py":<code python>
import os

def gotodir(arg, directory, files):
    for file in files:
        extName = os.path.splitext(file)[1];
        if extName == '.py':
            fullfilename = os.path.join(directory,file)
            print fullfilename
 
os.path.walk(".", gotodir, "")
</code>
==== Get Path of execute file ====
<code python>
import os

fullpathexecute = sys.argv[0]
pathofexecute = os.path.split(fullpathexecute)[0]
print pathofexecute
</code>
==== Read and Update File ====
<code python>
with open(filename, "rb") as f:
   content = f.read()
if content != "":
   #content = content.replace(oldstring, newstring)
   with open(filename, "wb") as f:
      f.write(content)
</code>
===== Python Command Line Arguments =====
refer: https://www.tutorialspoint.com/python/python_command_line_arguments.htm

Consider we want to pass two file names through command line and we also want to give an option to check the usage of the script. Usage of the script is as follows −
<code bash>
usage: test.py -i <inputfile> -o <outputfile>
</code>
Here is the following script to test.py −
<code python>
#!/usr/bin/python

import sys, getopt

def main(argv):
   inputfile = ''
   outputfile = ''
   try:
      opts, args = getopt.getopt(argv,"hi:o:",["ifile=","ofile="])
   except getopt.GetoptError:
      print 'test.py -i <inputfile> -o <outputfile>'
      sys.exit(2)
   for opt, arg in opts:
      if opt == '-h':
         print 'test.py -i <inputfile> -o <outputfile>'
         sys.exit()
      elif opt in ("-i", "--ifile"):
         inputfile = arg
      elif opt in ("-o", "--ofile"):
         outputfile = arg
   print 'Input file is "', inputfile
   print 'Output file is "', outputfile

if __name__ == "__main__":
   main(sys.argv[1:])
</code>
Now, run above script as follows −
  * Option1:<code bash>
$ test.py -h
</code>output:<code>
test.py -i <inputfile> -o <outputfile>
</code>
  * Option2:<code bash>
$ test.py -i inputfile
</code>output:<code>
Input file is " inputfile
Output file is "
</code>