brew extract --version=9.25 ghostscript [tap] what is tap?

Question

Tile says it all. Trying to install old version of ghostscript on a new mac.

brew extract --version=9.25 ghostscript <tap>

what should tap be? Or better how can one figure this out, teach me to fish.

Answer 1

According to the official Homebrew terminology, a tap is:

A Git repository of Formulae and/or commands

They are located under:

/usr/local/Homebrew/Library/Taps/

for Intel Mac, and under

/opt/homebrew/Library/Taps/

for M1 Mac.

You can create a local tap with:

brew tap-new user/repo

This will create a local git repository under /opt/homebrew/Library/Taps/user/repo/(for M1).

If you want to know more about tap, read the man page (man brew), read the documentation, and if you want to know even more read the source code.