env - run a program in a modified environment
man env will give you more information.
type env on command prompt and you will get the list of environmental variables defined.
.bash_profile ; /etc/profile and .bashrc
# .profile is for things that are not specifically related to Bash, like environment variables PATH and friends, and should be available anytime. For example, .profile should also be loaded when starting a graphical desktop session.
# .bashrc is for the configuring the interactive Bash usage, like Bash aliases, setting your favorite editor, setting the Bash prompt, etc.
# .bash_profile is for making sure that both the things in .profile and .bashrc are loaded for login shells.