stdin - seek() issue on Linux.

[Terry Reedy]

"Srihari Vijayaraghavan" <no at spam.please> wrote in message
news:WMTw8.46875$uR5.106037 at newsfeeds.bigpond.com...
> Hello,
>
> I am a new-bie python user. I have Python 2.2.1 installed on a Linux
> computer. I get the following error message when I try to seek() in
the
> stdin, like:
> #cat /var/log/messages | python test.py
> (where /var/log/messages is over 1MB in size)
>
> Traceback (most recent call last):
>   File "test.py", line 3, in ?
>     sys.stdin.seek(-512, 2)
> IOError: [Errno 29] Illegal seek

By 'cat'ting the random access disk file, you turned it into a
forward-access-only stream of bytes.  You definitely cannot seek
backwards (and maybe not forward - don't know).  Instead, open() the
file and use the resulting file object:

msgs = open("/var/log/messages", 'r')
msgs.seek(-512, 2)
...

Terry J. Reedy