I am writing a program that will take several days to execute :) and would
like to append to a log file but be able to open that file at any time and
see the errors that have occured.

So this is what I am doing:

----------------------------------------------
flog = open('out.log', 'a')
....
when needed:
sys.stdout=flog
print "error message"
------------------------------------------------

This will print directly to log. I use sys.stdout so i can quickly (in code)
change back and forth between errors displayed on screen and errors logged..

This works great. The only problem is that I cant see anything in the log
file when I try to open it say with notepad while the program is
running...and this is not good at all!

Any suggestions are appreciated.

Karim

- Write an autoflush class:
  class AutoFlush:
    def __init__(self, stream):
        self.stream = stream
    def write(self, text):
        self.stream.write(text)
        self.stream.flush()

  ...
  flog=open('out.log','a')
  flog=AutoFlush(flog)

  print >>flog,"I'm a message!"

Note that instead of changing stdout, you can also print directly to a
file with:
print >>flog,"Something to print"