Printenv

printenv shows the current environment variables.

Tips
Many shells provide their own version of this command. Check the docs of your shell.

Provided by
Most (all?) Linux distributions incorporate this from the GNU Coreutils: and use its man page

Related Commands
All of these relate to the context of the current session.
 * pwd - show the current working directory.
 * stty - show or alter terminal settings
 * tty - identify the controlling terminal