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
