fish has grown and evolved. i was referring to this:
Builtin commands should only be created when it cannot be avoided. echo, kill, printf and time are among the commands that fish does not implement internally since they can be provided as external commands. Several other commands that are commonly implemented as builtins and can not be implemented as external commands, including type, vared, pushd and popd are implemented as shellscript functions in fish.
if i remember correctly, this led to some useful commands that are builtin elsewhere to be external binaries shipped with fish. but since those where not actually tied to the fish shell they could run without it, and if they ended up on the global path be accessible from other shells.
the relevant text on the website has been changed, but it is referenced here:
If you wanna add a builtin like that to your own distribution of fish, you could do it cleanly by keeping those binaries in /usr/lib or /usr/libexec and then wrapping them in a fish function that ships in fish's install prefix. (This is basically how fish's Python scripts for generating completions from manpages are shipped today.)
Builtin commands should only be created when it cannot be avoided. echo, kill, printf and time are among the commands that fish does not implement internally since they can be provided as external commands. Several other commands that are commonly implemented as builtins and can not be implemented as external commands, including type, vared, pushd and popd are implemented as shellscript functions in fish.
if i remember correctly, this led to some useful commands that are builtin elsewhere to be external binaries shipped with fish. but since those where not actually tied to the fish shell they could run without it, and if they ended up on the global path be accessible from other shells.
the relevant text on the website has been changed, but it is referenced here:
https://github.com/fish-shell/fish-shell/issues/612
the discussion also points out that this has changed over time