rc.local hör till systemet och körs innan du får ett skall. Sedan är det ett gäng filer knutna till respektive skal, och dessa hittar du info om i respektive skals man-sida.
man bash
When bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable.