# What should the DESTINATION be for a header only library's CMake config file?
**URL:** https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473
**Category:** Usage
**Created:** [July 6, 2023, 5:46pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473 "2023-07-06T17:46:22Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [July 6, 2023, 5:46pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/1 "2023-07-06T17:46:22Z")
I have the following CMake code for a header only library that uses FILE\_SET.
My question is what is the optimal `DESTINATION` for the CMake config file generated.
It’s unclear to me what it should be for a header only library from looking at the documentation.
```auto
cmake_minimum_required(VERSION 3.23...3.26)
project(HEADER_ONLY LANGUAGES CXX)
add_library(bar INTERFACE)
add_library(foo::bar ALIAS bar)
target_sources(bar PUBLIC
FILE_SET bar_file_set
BASE_DIRS include
TYPE "HEADERS"
FILES include/bar.h
)
if (PROJECT_IS_TOP_LEVEL)
include(GNUInstallDirs)
install(TARGETS bar EXPORT barConfig FILE_SET bar_file_set)
install(EXPORT barConfig NAMESPACE "foo::" DESTINATION ?)
endif()
```
---
### Author:  [@craig.scott](https://discourse.cmake.org/u/craig.scott)
#### Post date: [July 7, 2023, 4:46am UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/2 "2023-07-07T04:46:23Z")
You can pick any location that would be searched by the default `find_package()` search path. My typical recommendations are:
- If the package contains binaries, then config files should be associated with the architecture-specific library subdirectory. On multi-architecture platforms, this matters because packages may be co-located under a common prefix, but libraries get installed to architecture-specific subdirectories below `lib`. To handle this in a convenient way, I put the package config files in `${CMAKE_INSTALL_LIBDIR}/cmake/`, where `${CMAKE_INSTALL_LIBDIR}` is provided by the `GNUInstallDirs` module.
- For packages that do not produce binaries (e.g. packages that provide CMake targets that are header-only libraries), it may be better to put the package config files in an architecture-independent location. For this, `share/cmake/` may be more suitable.
Note that whatever you choose, package managers may force the use of something else anyway in their own recipes. For example, from what I recall, vcpkg will force all scenarios to use `share/cmake/`. You don’t need to follow that in your own project, but do be aware that your choice may not be respected by others who repackage your project.
---
### Author:  [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [July 7, 2023, 4:05pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/3 "2023-07-07T16:05:40Z")
> [@craig.scott](#):
>
> For this, `share/cmake/` may be more suitable.
Gotcha, looking at `GNUInstallDirs` that translates to: `${CMAKE_INSTALL_DATADIR}/cmake/`
`DATAROOTDIR`
```
read-only architecture-independent data root (share)
```
`DATADIR`
```
read-only architecture-independent data (DATAROOTDIR)
```
---
### Author:  [@craig.scott](https://discourse.cmake.org/u/craig.scott)
#### Post date: [July 7, 2023, 10:39pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/4 "2023-07-07T22:39:16Z")
I was originally tempted to use `${CMAKE_INSTALL_DATADIR}` in my previous answer too, but that’s not what you want. The path searched by `find_package()` is `share`, it can’t be something else. The situation for `${CMAKE_INSTALL_LIBDIR}` is different because that is meant to handle cases like `lib/some-arch-specific-subdir`. There is no equivalent for `share`, so it has to literally be `share`, not whatever `${CMAKE_INSTALL_DATADIR}` evaluates to.
---
### Author:  [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [July 10, 2023, 5:11pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/5 "2023-07-10T17:11:49Z")
Thanks for the clarification. I’m updating our header only libraries to use `share/cmake/`.
I guess it was working fine since `DATADIR` was defaulting to `share`. However, from experience I know package managers can change these variables to suit their own means.
---
### Author:  [@Fido](https://discourse.cmake.org/u/Fido)
#### Post date: [July 21, 2024, 12:43pm UTC](https://discourse.cmake.org/t/what-should-the-destination-be-for-a-header-only-librarys-cmake-config-file/8473/6 "2024-07-21T12:43:42Z")
Thank you both! It’s unfortunate that these essential considerations are not explained in CMake documentation and tutorials.