Triplet is a standard term used in cross compiling as a way to completely capture the target environment (cpu, os, compiler, runtime, etc) in a single convenient name.
In Vcpkg, we use triplets to describe an imaginary "target configuration set" for every library. Within a triplet, libraries are generally built with the same configuration, but it is not a requirement. For example, you could have one triplet that builds `openssl` statically and `zlib` dynamically, one that builds them both statically, and one that builds them both dynamically (all for the same target OS and architecture). A single build will consume files from a single triplet.
We currently provide many triplets by default (run `vcpkg help triplet`). However, you can easily customize or add your own by copying a built-in triplet from the `triplets\` directory into a project local location. Then, use `--overlay-triplets=` (or equivalent such as [`$VCPKG_OVERLAY_TRIPLETS`](config-environment.md#vcpkg_overlay_triplets), [CMake `VCPKG_OVERLAY_TRIPLETS`](buildsystems/cmake-integration.md#vcpkg_overlay_triplets), or [MSBuild Additional Options](buildsystems/msbuild-integration.md#vcpkg-additional-install-options)) to add that directory to vcpkg. See our [overlay triplets example](../examples/overlay-triplets-linux-dynamic.md) for a more detailed walkthrough.
Because we do not have continuous coverage, port updates may break compatibility with community triplets. Because of this, community involvement is paramount!
You can set this value to `release` to only build release versions of the ports. By default this value is empty and release and debug versions of a port are built.
Specifies an alternate CMake Toolchain file to use.
This (if set) will override all other compiler detection logic. By default, a toolchain file is selected from `scripts/toolchains/` appropriate to the platform.
See also the CMake documentation for toolchain files: https://cmake.org/cmake/help/v3.11/manual/cmake-toolchains.7.html.
Set additional CMake configure options that are appended to the configure command (in [`vcpkg_cmake_configure`](../maintainers/ports/vcpkg-cmake/vcpkg_cmake_configure.md)).
This field is optional.
Also available as build-type specific `VCPKG_CMAKE_CONFIGURE_OPTIONS_DEBUG` and `VCPKG_CMAKE_CONFIGURE_OPTIONS_RELEASE` variables.
### VCPKG_MAKE_CONFIGURE_OPTIONS
Set additional automake / autoconf configure options that are appended to the configure command (in [`vcpkg_configure_make`](../maintainers/vcpkg_configure_make.md)).
This field is optional.
For example, to skip certain libtool checks that may errantly fail:
Setting `VCPKG_LOAD_VCVARS_ENV` to (true|1|on) changes this behavior so that the Visual Studio environment is setup following the same rules as if `VCPKG_CHAINLOAD_TOOLCHAIN_FILE` was not set.
Sets the install name used when building macOS dynamic libraries. Default value is `@rpath`. See the CMake documentation for [CMAKE_INSTALL_NAME_DIR](https://cmake.org/cmake/help/latest/variable/CMAKE_INSTALL_NAME_DIR.html) for more information.
### VCPKG_OSX_DEPLOYMENT_TARGET
Sets the minimum macOS version for compiled binaries. This also changes what versions of the macOS platform SDK that CMake will search for. See the CMake documentation for [CMAKE_OSX_DEPLOYMENT_TARGET](https://cmake.org/cmake/help/latest/variable/CMAKE_OSX_DEPLOYMENT_TARGET.html) for more information.
### VCPKG_OSX_SYSROOT
Set the name or path of the macOS platform SDK that will be used by CMake. See the CMake documentation for [CMAKE_OSX_SYSROOT](https://cmake.org/cmake/help/latest/variable/CMAKE_OSX_SYSROOT.html) for more information.
Set the macOS / iOS target architecture which will be used by CMake. See the CMake documentation for [CMAKE_OSX_ARCHITECTURES](https://cmake.org/cmake/help/latest/variable/CMAKE_OSX_ARCHITECTURES.html) for more information.
The CMake Macro `PORT` will be set when interpreting the triplet file and can be used to change settings (such as `VCPKG_LIBRARY_LINKAGE`) on a per-port basis.
The default triplet when running any vcpkg command is `%VCPKG_DEFAULT_TRIPLET%` or a platform-specific choice if that environment variable is undefined.
We recommend using a systematic naming scheme when creating new triplets. The Android toolchain naming scheme is a good source of inspiration: https://developer.android.com/ndk/guides/standalone_toolchain.html.
