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# The built-in function `open` opens a file and returns a file object. # Read mode opens a file for reading only. try: f = open("file.txt", "r") try: # Read the entire contents of a file at once. string = f.read() # OR read one line at a time. line = f.readline() # OR read all the lines into a list. lines = f.readlines() finally: f.close() except IOError: pass # Write mode creates a new file or overwrites the existing content of the file. # Write mode will _always_ destroy the existing contents of a file. try: # This will create a new file or **overwrite an existing file**. f = open("file.txt", "w") try: f.write('blah') # Write a string to a file f.writelines(lines) # Write a sequence of strings to a file finally: f.close() except IOError: pass # Append mode adds to the existing content, e.g. for keeping a log file. Append # mode will _never_ harm the existing contents of a file. try: # This tries to open an existing file but creates a new file if necessary. logfile = open("log.txt", "a") try: logfile.write('log log log') finally: logfile.close() except IOError: pass # There is also r+ (read and write) mode.