The particular initialization files responsible for your system's configuration depend on which shell the system administrator has specified as your default shell when your system was first installed. The Bourne shell is the default shell for SunOS, but you can also use the C shell or Korn shell. Each of these shells has its own initialization file (or files).
$ echo $SHELL /bin/sh
Look at the output of the command. If it is:
Regardless of the shell you are using, when you first login your system generally runs the system profile file, /etc/profile. This file is generally owned by the system administrator and is readable (but not writable) by all users.
After your system executes the system profile, it runs the user profile. The user profile is one (or more) initialization files that define your working environment. For example, if you're in the OpenWindows environment your system checks this file (or set of files) each time you start a new Shell Tool or Command Tool window.
Depending on which shell is set up as your default, your user profile can be one of the following:
.profile (for the Bourne and Korn shells)
.login and .cshrc (for the C shell)