bash startup load order

bash_startup_load_order.txt

If you have ever put something in a file like .bashrc and had it not work, or are
confused by why there are so many different files — .bashrc, .bash_profile, .bash_login,
.profile etc. — and what they do, this is for you.
The issue is that Bash sources from a different file based on what kind of shell it thinks
it is in. For an “interactive non-login shell”, it reads .bashrc, but for an “interactive 
login shell” it reads from the first of .bash_profile, .bash_login and .profile (only). 
There is no sane reason why this should be so; it’s just historical. Follows in more detail.
For Bash, they work as follows. Read down the appropriate column. Executes A, then B, then C,
etc. The B1, B2, B3 means it executes only the first of those files found.

+----------------+-----------+-----------+------+
|                |Interactive|Interactive|Script|
|                |login      |non-login  |      |
+----------------+-----------+-----------+------+
|/etc/profile    |   A       |           |      |
+----------------+-----------+-----------+------+
|/etc/bash.bashrc|           |    A      |      |
+----------------+-----------+-----------+------+
|~/.bashrc       |           |    B      |      |
+----------------+-----------+-----------+------+
|~/.bash_profile |   B1      |           |      |
+----------------+-----------+-----------+------+
|~/.bash_login   |   B2      |           |      |
+----------------+-----------+-----------+------+
|~/.profile      |   B3      |           |      |
+----------------+-----------+-----------+------+
|BASH_ENV        |           |           |  A   |
+----------------+-----------+-----------+------+
|                |           |           |      |
+----------------+-----------+-----------+------+
|                |           |           |      |
+----------------+-----------+-----------+------+
|~/.bash_logout  |    C      |           |      |
+----------------+-----------+-----------+------+