mjhjmtu

The three files are read in this order?

.bash_profile
.profile
.bashrc

This is not happening when I first open a terminal.

I have trace statements in the files appending to the file init.log. Please take a look at the following. It begins after opening a terminal. I have placed a comment to show where the log picks up after the su command.

stephen@debian:~$ cat init.log
reading .bashrc
done reading .bashrc
stephen@debian:~$ su - stephen
Password: 
stephen@debian:~$ cat init.log
reading .bashrc
done reading .bashrc
#
# after su
#
reading .bash_profile
reading .profile
reading .bashrc
done reading .bashrc
done reading .profile
done reading .bash_profile
stephen@debian:~$ 

So the su - login triggers the expected sequence however the initial login reads only the bashrc. This cannot be correct. Can someone explain under what conditions this would occur. I could modify the bashrc and profile files so that the initial read includes all expected files but I would rather get to the root of the problem and fix it there.

The answer is that bash will look for these three files (in slightly different situations) but will typically only execute one of them.

When running a login shell (typically when you log in on a terminal, or when you open a GNOME Terminal or similar, or when you use su -), more specifically an interactive login shell, then it will execute the system-wide /etc/profile and after that's done, it will look for ~/.bash_profile, ~/.bash_login or ~/.profile and execute the first of those that it finds.

From the bash man page:

When bash is invoked as an interactive login shell, or as a
non-interactive shell with the --login option, it first reads and
executes commands from the file /etc/profile, if that file exists.
After reading that file, it looks for ~/.bash_profile, ~/.bash_login,
and ~/.profile, in that order, and reads and executes commands from
the first one that exists and is readable. The --noprofile option may
be used when the shell is started to inhibit this behavior.

When bash is executed as an interactive shell, more specifically an interactive non-login shell, then it will read ~/.bashrc and execute that file.

From the bash man page:

When an interactive shell that is not a login shell is started, bash
reads and executes commands from ~/.bashrc, if that file exists.
This may be inhibited by using the --norc option. The --rcfile
file option will force bash to read and execute commands from file
instead of ~/.bashrc.

What Linux distributions usually do is ship ~/.bash_profile, ~/.profile and ~/.bashrc files that chain each other, so that you have more consistent behavior without having to duplicate settings between the files...

For instance, Debian's default ~/.profile contains this snippet:

# if running bash
if [ -n "$BASH_VERSION" ]; then
 # include .bashrc if it exists
 if [ -f "$HOME/.bashrc" ]; then
 . "$HOME/.bashrc"
 fi
fi

So it's explicitly sourcing ~/.bashrc, so that both login and non-login interactive shells will all include the customizations added to that file.