command -v Instead of type (Not POSIX)
typeis not required by POSIX
Up until today I thought type and which were POSIX. Apparently, they are not. Thanks to our good friend Juan on the live stream who is dutifully using shellcheck to look at everything we now know that which was never POSIX and that command -v should be used instead. We tested all variations of type and none of them with options are POSIX either even though I’ve always used type to check for the existence of something since it looks for aliases (and exported functions in Bash) but looks like command -v from now on for everything.
Note that command -v returns positive for functions and aliases as well as executables in the PATH. It seems that which is the only way to identify PATH commands.