read_file_backwards_buffer.py

import sys
def readfilerev(fd):
    buff = 256
    fd.seek(0,2)
    size = fd.tell()
    rem = size % buff
    pos = max(0, size - (buff + rem))
    line = ''
    while pos >= 0 :
        fd.seek(pos, 0)
        d = fd.read(buff+rem)
        rem = 0
        pos -= buff
        if '\n' in d:
            for c in reversed(d):
                if c == '\n':
                    if line:
                        yield line
                    line = c
                else:
                    line = c + line 
        else:
            line = d+line
    else:
        yield line

for l in readfilerev(open(sys.argv[1])):
    print l,