Below sample Python code is just one of the possible implementations for reading a file in reverse order. It's not that efficient as it reads the file one character at a time but does the job; especially, what you are looking is towards the end of the file and/or file is not too big.
import os
def ReverseRead(fname, separator=os.linesep):
with file(fname) as f:
f.seek(0, 2) # seek to the end of the file
fsize = f.tell() # get file size
r_cursor = 1
while r_cursor <= fsize:
a_line = ''
while r_cursor <= fsize:
f.seek(-1 * r_cursor, 2)
r_cursor += 1
c = f.read(1)
if c == separator and a_line:
r_cursor -= 1
break
a_line += c
a_line = a_line[::-1]
yield a_line
It's a generator function so it can be used in a loop. By default, it returns one line at each call. Here's a sample use of the code.
File to read: a.txt
$ cat delete
Line1: a b c d
Line2: z
Line3:
Reading the file one line at a time in reverse order:
>>> for i in ReverseRead('a.txt'):
... print i,
...
Line3:
Line2: z
Line1: a b c d
>>>
