bash config startup sequence

For Login shells (subject to the -noprofile option):

On logging in:
If `/etc/profile' exists, then source it.

If `~/.bash_profile' exists, then source it,
else if `~/.bash_login' exists, then source it,
else if `~/.profile' exists, then source it.

On logging out:
If `~/.bash_logout' exists, source it.

For non-login interactive shells (subject to the -norc and -rcfile options):
On starting up:
If `~/.bashrc' exists, then source it.

For non-interactive shells:
On starting up:
If the environment variable `ENV' is non-null, expand the variable and source the file named by the value. If Bash is not started in Posix mode, it looks for `BASH_ENV' before `ENV'.

So, typically, your `~/.bash_profile' contains the line
`if [ -f `~/.bashrc' ]; then source `~/.bashrc'; fi' after (or before) any login specific initializations.

If Bash is invoked as `sh', it tries to mimic the behavior of `sh' as closely as possible. For a login shell, it attempts to source only `/etc/profile' and `~/.profile', in that order. The `-noprofile' option may still be used to disable this behavior. A shell invoked as `sh' does not attempt to source any other startup files.

When Bash is started in POSIX mode, as with the `-posix' command line option, it follows the Posix 1003.2 standard for startup files. In this mode, the `ENV' variable is expanded and that file sourced; no other startup files are read.