For a long time people have requested some sort of configuration files
for Homebrew. Now: here's the first version of that.
Similarly to how you can configure Git for a system, a repository or
a user: you can configure Homebrew for a system, a prefix or a user.
The system-wide configuration file is `/etc/homebrew/brew.env`, the
prefix-specific configuration file is
`$HOMEBREW_PREFIX/etc/homebrew/brew.env`
and the user-specific configuration file is `~/.homebrew/brew.env`.
As we need to read these files from Bash in `bin/brew` (so they can)
influence functionality ASAP: they are in a simple format that Bash
can read. It may be that we have more complex array or hash data in
future that's configured through JSON or YAML (most likely JSON as we
use it more) and stored in a `brew.json`/`brew.yaml` file in the same
directory.
As this is relying on `eval` in Bash which is fairly dangerous: we
filter the lines with a regex to ensure we're only permitting setting
`HOMEBREW_*` variables and nothing more.
To give a bit of power to system administrators, the
`HOMEBREW_SYSTEM_ENV_TAKES_PRIORITY` variable can be set in
`/etc/homebrew/brew.env` to ensure that the system-wide configuration
file is loaded last and overrides any prefix or user settings.
Now that we have an actual location for configuration files, let's also
change the `brew livecheck` watchlist configuration file to be in this
directory and deprecate the existing location. As this is a developer
command and the mitigation is to just move the file: we don't need to
follow the normal deprecation process here.
We added the `--all` flag (now renamed to `--eval-all`) for various
commands for this behaviour so let's start deprecating this.
Also, introduce a `HOMEBREW_EVAL_ALL` environment variable to use the
existing, less secure, behaviour by default and avoid passing
`--eval-all` everywhere.
When running `brew livecheck --cask` or `brew livecheck --formula`,
livecheck wasn't properly respecting these flags. It should have
worked by only including the casks or formulae in the watchlist but
instead these flags were treating all the names in the watchlist as
formulae or casks, which doesn't work properly.
This addresses the issue by always using `#to_formulae_and_casks`
on the watchlist names and then using `#reject` to conditionally
exclude formulae or casks based on whether the related flags were
passed to `brew livecheck`.
