The system runs your .profile whenever you log in.

When you create a new user account, the user's initial .profile is copied from /etc/skel/.profile (see Managing User Accounts). Here's what's in that file:

# default .profile
if test "$(tty)" != "not a tty"; then
echo 'edit the file .profile if you want to change your environment.'

This profile runs the tty utility to get the name of the terminal that's open as standard input. If there is a terminal, .profile simply displays a helpful hint.

You might want to set some environment variables:

The path to your favorite editor (the default is vi).
The name of the profile that ksh should run whenever you start a shell.