Frequently Asked Question

What is the difference between a login shell and an interactive shell?

These are two different axes, not synonyms. A login shell is one started by the login process, when you sign in at a virtual console, over SSH, or in a graphical display manager that runs a login shell. It's the shell that sets up your environment for the whole session. A non-login shell is anything started later: opening a new tab in your terminal emulator, running bash from within another shell, or executing a script.

An interactive shell is one with a prompt, you type, it responds. A non-interactive shell is one running a script with no prompt. The two axes combine: an SSH login is both interactive and login; opening a new terminal window is interactive but not login; running bash myscript.sh is non-interactive and non-login. The distinction matters because bash reads different startup files in each case: login shells read ~/.bash_profile, interactive non-login shells read ~/.bashrc, and non-interactive shells read neither unless BASH_ENV is set.