writing back into the same file after reading from the file

writing back into the same file after reading from the file

Use a temporary file. Python provides facilities for creating temporary files
in a secure manner. Call example below with: python modify.py target_filename

 import tempfile import sys def modify_file(filename):      #Create temporary file read/write      t = tempfile.NamedTemporaryFile(mode="r+")      #Open input file read-only      i = open(filename, 'r')      #Copy input file to temporary file, modifying as we go      for line in i:t.write(line.rstrip()+"n")      i.close() #Close input file      t.seek(0) #Rewind temporary file to beginning      o = open(filename, "w")  #Reopen input file writable      #Overwriting original file with temporary file contents     for line in t:o.write(line)      t.close() #Close temporary file, will cause it to be deleted if __name__ == "__main__":      modify_file(sys.argv[1])

References here: http://docs.python.org/2/library/tempfile.html