68 lines
2.7 KiB
Markdown
68 lines
2.7 KiB
Markdown
# How to Build Software Outside Homebrew with Homebrew `keg_only` Dependencies
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## What does "keg-only" mean?
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The [FAQ](FAQ.md#what-does-keg-only-mean) briefly explains this.
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As an example:
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*OpenSSL isn’t symlinked into my `PATH` and non-Homebrew builds can’t find it!*
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This is because Homebrew keeps it locked inside its individual prefix, rather than symlinking to the publicly-available location, usually `/usr/local`.
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## Advice on potential workarounds
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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.
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*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.
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`brew link --force` creates a warning in `brew doctor` to let both you and maintainers know that a link exists that could be causing issues. If you’ve linked something and there’s no problems at all? Feel free to ignore the `brew doctor` error.
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## How do I use those tools outside of Homebrew?
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Useful, reliable alternatives exist should you wish to use `keg_only` tools outside of Homebrew.
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### Build flags
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You can set flags to give configure scripts or Makefiles a nudge in the right direction. An example of flag setting:
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```sh
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./configure --prefix=/Users/Dave/Downloads CFLAGS=-I$(brew --prefix)/opt/openssl/include LDFLAGS=-L$(brew --prefix)/opt/openssl/lib
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```
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An example using `pip`:
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```sh
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CFLAGS=-I$(brew --prefix)/opt/icu4c/include LDFLAGS=-L$(brew --prefix)/opt/icu4c/lib pip install pyicu
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```
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### `PATH` modification
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You can temporarily prepend your `PATH` with the tool’s `bin` directory, such as:
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```sh
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export PATH=$(brew --prefix)/opt/openssl/bin:$PATH
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```
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This will prepend that folder to your `PATH`, ensuring any build script that searches the `PATH` will find it first.
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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.
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### `pkg-config` detection
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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.
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An example of this is:
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```sh
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export PKG_CONFIG_PATH=$(brew --prefix)/opt/openssl/lib/pkgconfig
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```
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If you’re curious about the `PKG_CONFIG_PATH` variable `man pkg-config` goes into more detail.
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You can get `pkg-config` to detail the default search path with:
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```sh
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pkg-config --variable pc_path pkg-config
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```
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