Use the `reason` attribute to be able to handle `UsageError` subclasses
more uniformly and simplify logic in `brew.rb` to handle them together.

Instead of always printing the generic help text, print command-specific
help if it is available and a command raised the `UsageError` exception.
Put the error message underneath the help text (was above) to avoid that
it scrolls off the screen.

Thereby fix a regression where handling the invalid usage would fail to
access `ARGV.usage` removed in c6536066.

Turns out making `empty_argv` a boolean argument for `Homebrew.help` was
not the best idea and having command-to-path mapping and help extraction
in a single method is not flexible enough.

Also only complain about missing help text when `HOMEBREW_DEVELOPER=1`
and otherwise just print the generic help text.

Library/brew.rb:108: warning: `*' interpreted as argument prefix

Showing help makes sense for `brew help <command>`, but showing it for
`brew <command> help` is undesirable and prevents all commands from
accepting a named argument `help` (formula, tap, file name, etc.).

All other help flags are still detected before *and* after the command.

Closes #103.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Keep the footprint of `brew.rb` small. Handle fetching/displaying an
appropriate help text (taking into account various external conditions)
in the `help` command.

Don't exit with a non-zero status code just because an internal command
happens to be undocumented. Also print the generic help in these cases
to provide some help (including a reference to the man page).

This is also used by `brew <cmd> --help`. The basic idea is to have the
documentation as a top level comment in each command file. To find these
comments, they have to be like this `#:`.

This is also used by the `brew man` command to keep the documentation
DRY, and for that there are now a header and footer for the man page.

`Library/ENV` like `Library/Homebrew` is part of Homebrew basecode. It
should be able to be accessed during the `brew tests`.

By adding HOMEBREW_ENV_PATH variable, we allow test suit to locate these
codes.

This means that internal command aliases can be used for Bash commands
(such as the new, Bash-based `brew update`).

Fixes Homebrew/homebrew#49182.

Closes Homebrew/homebrew#49184.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Because `brew.rb` should never be invoked directly, remove executable
bit and shebang to make that more obvious.

Closes Homebrew/homebrew#48816.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

Currently HOMEBREW_BREW_FILE is a String, while other of HOMEBREW_*
variables are all Pathname. This commit unifies them all as Pathname,
so it will not cause any confusion.

Closes Homebrew/homebrew#48872.

Signed-off-by: Xu Cheng <xucheng@me.com>

Closes Homebrew/homebrew#48634.
Closes Homebrew/homebrew#48681.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Not sure why this is happening (beyond the Chef cookbook stupidly
deciding to not call through `bin/brew`) but fail and print a scary
looking error to hope to point people in the right direction.

Closes Homebrew/homebrew#48261.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

`bin/brew` already sets up a bunch of environment variables. There's no
need to re-export them for external commands. (`HOMEBREW_LIBRARY_PATH`
and `HOMEBREW_CACHE` continue to be determined later in the Ruby code.)

Generated by `brew style --fix Library/brew.rb`

This is now handled by `bin/brew`

Before this, `sudo brew cask` will auto install Homebrew cask as root
user. This will cause permission problem for files in `Tap` directory.

Therefore, let's check process uid and switch to normal user for tap.
As result, `sudo brew cask` will work as the same before, except tap
files will have the correct permission attributes.

Closes Homebrew/homebrew#48059.

Signed-off-by: Xu Cheng <xucheng@me.com>

Also, print as a warning to STDERR and print a backtrace in debug mode.

Closes Homebrew/homebrew#47099.

Closes Homebrew/homebrew#47154.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Make both `--version` and `-v` print the Homebrew version and exit, if
provided as first and sole argument. `brew --version` no longer accepts
additional arguments (they were previously ignored). Otherwise interpret
`brew -v <arguments>` as if `brew <arguments> -v` was executed instead
(no change here), but no longer print a line with the Homebrew version.

Closes Homebrew/homebrew#46790.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

So we can remove the formula installation from `brew.rb`.

Closes Homebrew/homebrew#46843.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Otherwise it would assume if `cask` was tapped it was also installed.

Closes Homebrew/homebrew#45773.

Signed-off-by: Xu Cheng <xucheng@me.com>

`reinstall` can currently be executed under sudo and has every chunk of problems
running install under sudo does when `brew` isn't root owned.

Likewise with `postinstall` which we increasingly use to create directories and
move/install files elsewhere. Using sudo there both masks deeper issues and
makes uninstall troublesome.

Closes Homebrew/homebrew#45112.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

The xcrun code is stolen right out of the INSTALL script.

Check for user agreement of the Xcode license before permitting any other brew usage to continue.
This prevents the situation where people are instructed to "please re-run as root via sudo" on brew commands.
The check can only fail when Xcode is installed & the active developer dir.

Closes Homebrew/homebrew#44974.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

HOMEBREW_VERSION doesn't change very often; the repository state is more
interesting.

Closes Homebrew/homebrew#41886.

Closes Homebrew/homebrew#42354.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Closes Homebrew/homebrew#42069.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Closes Homebrew/homebrew#41034.

Signed-off-by: Xu Cheng <xucheng@me.com>

This is unnecessary here because we use it only once. The difference
won't be noticeable but the check is ~5 times faster now.

Closes Homebrew/homebrew#40901.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Fixes Homebrew/homebrew#40778.

Issue a warning about Homebrew's very basic support for 10.11 at this point
in time on each run of `brew`.

Closes Homebrew/homebrew#40536.

Signed-off-by: Dominyk Tiller <dominyktiller@gmail.com>

Is this really Misty?!