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 add your own by creating a new file in the `triplets\` directory. The new triplet will immediately be available for use in commands, such as `vcpkg install boost:x86-windows-custom`.
Because we do not have continuous coverage, port updates may break compatibility with community triplets. Because of this, community involvement is paramount!
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.
Instructs vcpkg to allow additional environment variables into the build process.
On Windows, vcpkg builds packages in a special clean environment that is isolated from the current command prompt to ensure build reliability and consistency.
This triplet option can be set to a list of additional environment variables that will be added to the clean environment.
See also the `vcpkg env` command for how you can inspect the precise environment that will be used.
> Implementers' Note: this list is extracted via the `vcpkg_get_tags` mechanism.
If `VCPKG_CHAINLOAD_TOOLCHAIN_FILE` is used, VCPKG will not setup the Visual Studio environment.
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.
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.
