def tail(f, n, offset=None): """Reads a n lines from f with an offset of offset lines. The return value is a tuple in the form ``(lines, has_more)`` where `has_more` is an indicator that is `True` if there are more lines in the file. """ avg_line_length = 74 to_read = n + (offset or 0) while 1: try: f.seek(-(avg_line_length * to_read), 2) except IOError: # woops. apparently file is smaller than what we want # to step back, go to the beginning instead f.seek(0) pos = f.tell() lines = f.read().splitlines() if len(lines) >= to_read or pos == 0: return lines[-to_read:offset and -offset or None], len(lines) > to_read or pos > 0 avg_line_length *= 1.3
