Setting up any UNIX like system comes down to a single startup file. There could be many, if one wants to, the freedom is always there. But generally it starts at a single point.

OSX / MacOS

In this land the file is .bash_profile. Almost all the things can be configured here.

UBUNTU / Linux

Here the file is .bashrc. All the PATH and systemwide settings reside here.

Both of these files stay in the root of the user home folder in both MacOS and UBUNTU. This folder is referred as ~/ in both the Operating Systems.

On UBUNTU, one can put the configuration in .bash_profile, but then to see the effect, the requirement is to logout of the system and login again.