/etc/profile Executed when the user logs in
~/.profile Executed when the user logs in
~/.bashrc Executed when BASH is launched
~/.bash_logout Executed when the user logs out
If you want to modify one of the standard scripts that should reside in your home directory, but find that your home directory does not contain the indicated file, simply create the file. The next time you log in, log out, or launch BASH (as appropriate) the shell will execute your script.