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

I had to do this some time ago and used the below code. It pipes to the shell. I am afraid i do not have the complete script anymore. If you are on a unixish operating system, you can use "tac", however on e.g. Mac OSX tac command does not work, use tail -r. The below code snippet tests for which platform you're on, and adjusts the command accordingly

# We need a command to reverse the line order of the file. On Linux this
# is 'tac', on OSX it is 'tail -r'
# 'tac' is not supported on osx, 'tail -r' is not supported on linux.

if sys.platform == "darwin":
    command += "|tail -r"
elif sys.platform == "linux2":
    command += "|tac"
else:
    raise EnvironmentError('Platform %s not supported' % sys.platform)