Keg-only

ruby@2.7 is keg-only, which means it was not symlinked into /usr/local, because this is an alternate version of another formula.

[email protected] is keg-only, which means it was not symlinked into /Users/MY_USER/brew,

because this is an alternate version of another formula.

libpq is keg-only, which means it was not symlinked into /opt/homebrew,
because conflicts with postgres formula.

brew info --json helm@2
  "keg_only": true,
  "keg_only_reason": {
    "reason": ":versioned_formula",
    "explanation": ""
  },

See also

• Ruby, Sinatra, Ruby on rails, RubyGems, gem, bundle, Rack, Gemfile, Keg-only, brew install [email protected], bundle, JRuby, CocoaPods, apt install ruby, Fog, Puma
• Homebrew, brew, pkgutil, /opt/homebrew/, installation