Python basic examples

• Executing a shell command

  os.system()

• Get the users environment

  os.environ()

• Returns the current working directory

  os.getcwd()

• Return a list of the entries in the directory given by path

  os.listdir(path)

• Create a directory named path with numeric mode mode

  os.mkdir(path)

• Recursive directory creation function

  os.makedirs(path)

• Remove (delete) the file path

  os.remove(path)

• Remove directories recursively

  os.removedirs(path)

• Rename the file or directory src to dst

  os.rename(src, dst)

• Remove (delete) the directory path

  os.rmdir(path)

• split:

  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)

  output:

  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')

• using os.path to check what a filename represents

  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

  output:

  . => EXISTS ISDIR
  / => EXISTS ISABS ISDIR ISMOUNT
  file =>
  /file => ISABS
  samples => EXISTS ISDIR
  samples/sample.jpg => EXISTS ISFILE
  directory/file =>
  ../directory/file =>
  /directory/file => ISABS

• Using os.path to handle filename

  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'

  ⇒ output

  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

• get normal path

  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

  output:

  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

• urlparse

  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)

  output:

  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

• using os.path.walk list all file in current directory and all subdirectories

  import os
   
  def gotodir(arg, directory, files):
      for file in files:
          print file
   
  os.path.walk(".", gotodir, "")

  Output

  .project
  .pydevproject
  conent.tpl
  index.html
  parser.py
  test.py

• using os.path.walk list all full filename in current directory and all subdirectories

  import os
   
  def gotodir(arg, directory, files):
      for file in files:
          fullfilename = os.path.join(directory,file)
          print fullfilename
   
  os.path.walk(".", gotodir, "")

• Find all files with extension “.py”:

  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, "")

import os
 
fullpathexecute = sys.argv[0]
pathofexecute = os.path.split(fullpathexecute)[0]
print pathofexecute

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)

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 −

usage: test.py -i <inputfile> -o <outputfile>

Here is the following script to test.py −

#!/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:])

Now, run above script as follows −

• Option1:

  $ test.py -h

  output:

  test.py -i <inputfile> -o <outputfile>

• Option2:

  $ test.py -i inputfile

  output:

  Input file is " inputfile
  Output file is "