Interactive startup file

Brendhan Horne brendhanhorne at
Sun Mar 18 01:22:15 CET 2001

In the tutorial it  says in section 2.2.3
When you use Python interactively, it is frequently handy to have some
standard commands executed every time the interpreter is started. You can do
this by setting an environment variable named $PYTHONSTARTUP to the name of
a file containing your start-up commands. This is similar to the .profile
feature of the Unix shells.

This file is only read in interactive sessions, not when Python reads
commands from a script, and not when /dev/tty is given as the explicit
source of commands (which otherwise behaves like an interactive session). It
is executed in the same namespace where interactive commands are executed,
so that objects that it defines or imports can be used without qualification
in the interactive session. You can also change the prompts sys.ps1 and
sys.ps2 in this file.

If you want to read an additional start-up file from the current directory,
you can program this in the global start-up file, e.g. "if
os.path.isfile(''): execfile('')". If you want to
use the startup file in a script, you must do this explicitly in the script:

import os
filename = os.environ.get('PYTHONSTARTUP')
if filename and os.path.isfile(filename):

Can some one please explain this to me in novice english and for a guy who
is using windows98 with his python.


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