[lewiscollard]

> but I guess there is at least this precedent for using the word like that.

In Windows 3.1, the SYSTEM.INI had a setting called "shell" for overriding the default program started after Windows had loaded. Use of the word "shell" in this sense to describe a graphical interface dates back at least this far.

There was also a crude character-mode graphical interface called MS-DOS Shell, in 1988.

"shell" might be best generalised as "the first interactive program to run after boot" rather than "command line interface".

[omnibrain]

It's the shell around the core.

[jolmg]

Yes, but because CLIs came before TUIs/GUIs, I thought it only caught with CLIs until Unity (2011) adopted it for GUIs. Turns out there's been some GUIs that have used the term since Windows 3.1 and a TUI in 1988.