Disable brew cask

[sjackman]

Display a message that brew cask distributes Mac applications and is not available for Linuxbrew.

[sjackman]

$ brew cask install google-chrome
Error: Permission denied @ dir_s_mkdir - /Library
  Most likely, this means you have an outdated version of homebrew-cask.

Not very helpful.

[jbcpollak]

This would be great, we use homebrew-bundle to install a bunch of programs through a Brewfile, and a bunch of them are Mac casks. It would be nice to ignore those instead of throwing errors.

[sjackman]

I'd be happy to accept a PR that improves the above error message and ignores casks in the Brewfile (probably two separate PRs).

[jbcpollak]

@sjackman should the PR be for this project or homebrew-bundle? Maybe this should be bug in that project?

Or should it just be in this project to ignore all attempts at cask execution?

[sjackman]

You can ask https://github.com/Homebrew/homebrew-bundle whether they would like to support Linux; my guess would be no, but I could be wrong. Linuxbrew does not yet have a fork of homebrew-bundle. I don't have the time myself to maintain that fork. Someone else could step up, if they wanted to fill that role. Linuxbrew/brew could definitely use a patch to give an informative message whenever a brew cask command is run saying that Linuxbrew does not yet support casks.

[rwhogg]

I fixed this here but forgot to close this issue when I did so.