title: Rename a file that already exists
body: <p>I'm learning python and also english. And I have a problem that might be easy, but I can't solve it. I have a folder of .txt's, I was able to extract by regular expression a sequence of numbers of each one. I rename each file with the sequence I extracted from .txt</p>
  
  <pre><code>path_txt = (r'''C:\Users\user\Desktop\Doc_Classifier\TXT''')
  
  for TXT in name_files3:
      with open(path_txt + '\\' + TXT, "r") as content:
          search = re.search(r'(([0-9]{4})(/)(([1][9][0-9][0-9])|([2][0-9][0-9][0-9])))', content.read())
  
      if search is not None:
          name3 = search.group(0)
          name3 = name3.replace("/", "")
          os.rename(os.path.join(path_txt, TXT),
                    os.path.join("Processos3", name3 + "_" + str(random.randint(100, 999)) + ".txt"))
  </code></pre>
  
  <p>I need to check if the file already exists, and rename it by adding an increment. Currently to differentiate the files I am adding a random number to the name (random.randint(100, 999))</p>
  
  <p>PS: Currently the script finds "7526/2016" in .txt, by regular expression. Remove the "/". Rename the file with "75262016" + a random number (example: 7526016_111). Instead of renaming using a random number, I would like to check if the file already exists, and rename it using an increment (example: 7526016_copy1, 7526016_copy2)</p>