BASH Shell will attempt to load several configuration files during the initialization. There are 2 sets of configuration files, depending it’s a login-shell, or non-login shell.
- When you login a server on a bare metal monitor, or via SSH, or with # su – [username], you get a login shell.
- When you start a shell in a terminal in an existing session (gnome-terminal, a shell inside another, or with # su [username]…), you get a non-login shell. A shell script is also executed under a non-login shell.
Below we’ll illustrate the difference by adding some debugging into those configuration files.
By default, a login shell will load the following files:
# su - test this is /etc/profile this is ~/.bash_profile this is ~/.bashrc this is /etc/bashrc
Here note the ~/.bash_profile file, the file by default call ~/.bashrc, and ~/.bashrc call /etc/bashrc.
If for some reason BASH don’t find the file ~/.bash_profile, it will look for ~/.bash_login instead. If again ~/.bash_login cannot be found, BASH will look for ~/.profile instead.
And in the 2 cases, ~/.bashrc, and /etc/bashrc won’t be loaded, unless they were explicitly called in ~/.bash_login or ~/.profile.
The examples when ~/.bash_profile doesn’t exist:
– With presence of ~/.bash_login, no matter ~/.profile exist or not:
$ su - test Password: this is /etc/profile This is ~/.bash_login
– Only ~/.profile:
# su - test this is /etc/profile this is ~/.profile
It’s easier, BASH only load the ~/.bashrc, and again, the file call /etc/bashrc.
# su test this is ~/.bashrc this is /etc/bashrc