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diff --git a/docs/How-to-build-software-outside-Homebrew-with-Homebrew-keg-only-dependencies.md b/docs/How-to-build-software-outside-Homebrew-with-Homebrew-keg-only-dependencies.md new file mode 100644 index 000000000..f71c75164 --- /dev/null +++ b/docs/How-to-build-software-outside-Homebrew-with-Homebrew-keg-only-dependencies.md @@ -0,0 +1,68 @@ +# How to build software outside Homebrew with Homebrew `keg-only` dependencies + +## What does `keg-only` mean? + +The [FAQ](FAQ.md) briefly explains this. + +As an example: + +*OpenSSL isn’t symlinked into my `$PATH` and non-Homebrew builds can’t find it!* + +This is because Homebrew keeps it locked inside its individual prefix, rather than symlinking to the publicly-available location, usually `/usr/local`. + +## Advice on potential workarounds. + +A number of people in this situation are either forcefully linking `keg_only` tools with `brew link --force` or moving default system utilities out of the `$PATH` and replacing them with manually-created symlinks to the Homebrew-provided tool. + +*Please* do not remove macOS native tools and forcefully replace them with symlinks back to the Homebrew-provided tool. Doing so can and likely will cause significant breakage when attempting to build software. + +`brew link --force` creates a warning in `brew doctor` to let both you and maintainers know that link exists and could be causing issues. If you’ve linked something and there’s no problems at all? Feel free to ignore the `brew doctor` error. + +## How do I use those tools outside of Homebrew? + +Useful, reliable alternatives exist should you wish to use `keg_only` tools outside of Homebrew. + +### Build flags: + + +You can set flags to give configure scripts or Makefiles a nudge in the right direction. An example of flag setting: + +```shell +./configure --prefix=/Users/Dave/Downloads CFLAGS=-I$(brew --prefix)/opt/openssl/include LDFLAGS=-L$(brew --prefix)/opt/openssl/lib +``` + +An example using `pip`: + +```shell +CFLAGS=-I$(brew --prefix)/opt/icu4c/include LDFLAGS=-L$(brew --prefix)/opt/icu4c/lib pip install pyicu +``` + +### `$PATH` modification: + +You can temporarily prepend your `$PATH` with the tool’s bin directory, such as: + +```shell +export PATH=$(brew --prefix)/opt/openssl/bin:$PATH +``` + +This will prepend that folder to your `$PATH`, ensuring any build script that searches the `$PATH` will find it first. + +Changing your `$PATH` using that command ensures the change only exists for the duration of that shell session. Once you are no longer in that session, the `$PATH` reverts to the prior state. + +### `pkg-config` detection: + +If the tool you are attempting to build is [pkg-config](https://en.wikipedia.org/wiki/Pkg-config) aware, you can amend your `PKG_CONFIG_PATH` to find that `keg_only` utility’s `.pc` file, if it has them. Not all formulae ship with those files. + +An example of that is: + +```shell +export PKG_CONFIG_PATH=$(brew --prefix)/opt/openssl/lib/pkgconfig +``` + +If you’re curious about the `PKG_CONFIG_PATH` variable `man pkg-config` goes into more detail. + +You can get `pkg-config` to detail the default search path with: + +```shell +pkg-config --variable pc_path pkg-config +``` |