What type of user interface does GNOME Terminal have?
I read here that a terminal emulator is just a wrapper program that runs a (command-line) shell.
So we can type different commands into this shell (which runs inside a terminal application). In particular, we can use commands to launch different applications. And each application has its own user interface. For example, there are CLI applications, TUI applications, and GUI applications. CLI and TUI applications are opened inside a terminal window, while GUI applications are opened outside this window.
Since a terminal emulator is also a program (application), what type of user interface does a terminal emulator have? Specifically, what type of user interface does GNOME Terminal have? (CLI / TUI / GUI)
Wikipedia says that
Although GNOME Terminal is primarily a command-line interface and uses the keyboard for most input, GNOME Terminal has limited support for mouse events.
My hypothesis is that the default user interface of GNOME Terminal is CLI, but when we launch (using the command-line shell) any TUI application in this terminal, the user interface of GNOME Terminal changes to TUI… Am I right?
GNOME Terminal is a GUI application by itself, because you can use the menus and change the settings of the application using a GUI. Below you have a preferences window of GNOME Terminal – it’s definitely a GUI.
The programs that are run inside a terminal session have user interface of their own, which is separate from the UI of the terminal itself.
While the typical case is that you run a shell inside a terminal session, it doesn’t need to be so. You can configure (using the preferences window above :)) a different program to launch automatically when you open the terminal.
Shell itself is of course a textbook example of CLI; but you can run different programs from a shell, and they can be either CLI, TUI or even GUI.