BASH_PROFILE, Bash Interactive Login Shell File (.bash_profile)
The BASH_PROFILE System file format
Files with the BASH_PROFILE extension are used by terminal programs on Mac OS X and Linux computers. These terminals use a variety of shell files and BASH_PROFILE is one of them. The information inside the BASH_PROFILE file includes setup instructions that is used by the shell to setup an environment. This includes variables and (default) scripts. BASH_PROFILE are used by interactive login shells. They automatically set certain command prompt preferences or paths to directories and programs.
Technical details of BASH_PROFILE files
Since the BASH_PROFILE file is used by interactive login shells, it is run after the user entered their login credentials. These files are usually hidden on the hard drive and cannot be easily or accidentally accessed. Furthermore, BASH_PROFILE files are saved without the filename prefix and thus only consist of the file extension. In contrast to the BASH_PROFILE file that is used for interactive login, non-interactive login shells use the BASHRC file.