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.
To change the triplet used by your project, you can pass `--triplet=<triplet>` on the command line or see our [Buildsystem-Specific Documentation](buildsystems/integration.md).
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/vcpkg_cmake_configure.md)).
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.
