How to read a file in reverse order?

Question

How to read a file in reverse order using python? I want to read a file from last line to first line.

Answer 1

How about something like this:

import os


def readlines_reverse(filename):
    with open(filename) as qfile:
        qfile.seek(0, os.SEEK_END)
        position = qfile.tell()
        line = ''
        while position >= 0:
            qfile.seek(position)
            next_char = qfile.read(1)
            if next_char == "\n":
                yield line[::-1]
                line = ''
            else:
                line += next_char
            position -= 1
        yield line[::-1]


if __name__ == '__main__':
    for qline in readlines_reverse(raw_input()):
        print qline

Since the file is read character by character in reverse order, it will work even on very large files, as long as individual lines fit into memory.