` is the package to be found. The package root variables are maintained as a stack so if called from within a find module, root paths from the parent’s find module will also be searched after paths for the current package. This can be skipped if `NO_PACKAGE_ROOT_PATH` is passed or by setting the [`CMAKE_FIND_USE_PACKAGE_ROOT_PATH`](https://cmake.org/cmake/help/latest/variable/CMAKE_FIND_USE_PACKAGE_ROOT_PATH.html#variable:CMAKE_FIND_USE_PACKAGE_ROOT_PATH) to `FALSE`. See policy [`CMP0074`](https://cmake.org/cmake/help/latest/policy/CMP0074.html#policy:CMP0074).
Basically can either do a more global approach or a more narrow approach
- Global: You can set [CMAKE\_FIND\_ROOT\_PATH](https://cmake.org/cmake/help/latest/variable/CMAKE_FIND_ROOT_PATH.html#variable:CMAKE_FIND_ROOT_PATH) so that all find\_\* calls looks there first.
- Or set the root path for each individual package: [PackageName\_ROOT](https://cmake.org/cmake/help/latest/variable/PackageName_ROOT.html#variable:%3CPackageName%3E_ROOT)
```auto
# So basically I think you want the more global approach
# “How can we force cmake to check that dependencies must firstly be looked up in a certain directory instead of default /usr/bin/, /usr/lib/, etc Linux dirs., then that default, in that order”
# Let's say 'certain directory' is called foobar
set(foobar "C:/foobar")
list(APPEND CMAKE_FIND_ROOT_PATH "${foobar}")
# Now it will look at "C:/foobar" first.
find_package(OpenImageIO 2.1.12 REQUIRED)
```
I think that answers your primary question.
> [@abd](#):
>
> I’m a newbie on Cmake … also what’s the difference of CMakeLists.txt and .cmake files
You are overloading your question. So I’ll just suggest you checkout this book.
> **[Professional CMake: A Practical Guide](https://crascit.com/professional-cmake/)**
>
> The handbook for every CMake user, providing structured learning, the latest best practices, and real-world advice from a CMake co-maintainer.
---
### Author:  [@anon45792294](https://discourse.cmake.org/u/anon45792294)
#### Post date: [March 3, 2021, 3:38am UTC](https://discourse.cmake.org/t/how-let-cmake-know-that-dependencies-must-firstly-be-from-a-certain-location/2875/3 "2021-03-03T03:38:16Z")
Also it’s more helpful to users in the future that you just paste the code that is causing you problems instead of linking to the GitHub.
Something like this would suffice:
```auto
cmake_minimum_required(VERSION 3.13 FATAL_ERROR)
project(olive-editor VERSION 0.2.0 LANGUAGES CXX)
...
find_package(OpenGL REQUIRED)
find_package(OpenColorIO 2.0.0 REQUIRED)
find_package(OpenImageIO 2.1.12 REQUIRED)
find_package(OpenEXR REQUIRED)
find_package(Qt5 5.6 REQUIRED
COMPONENTS
Core
Gui
Widgets
Multimedia
OpenGL
Svg
LinguistTools
Concurrent
)
find_package(FFMPEG 3.0 REQUIRED
COMPONENTS
avutil
avcodec
avformat
avfilter
swscale
swresample
)
find_package(OpenTimelineIO)
```
---
### Author:  [@anon45792294](https://discourse.cmake.org/u/anon45792294)
#### Post date: [March 3, 2021, 3:40am UTC](https://discourse.cmake.org/t/how-let-cmake-know-that-dependencies-must-firstly-be-from-a-certain-location/2875/4 "2021-03-03T03:40:35Z")
Also I just checked out your project very cool 😃
---
### Author:  [@anon45792294](https://discourse.cmake.org/u/anon45792294)
#### Post date: [March 9, 2021, 3:28am UTC](https://discourse.cmake.org/t/how-let-cmake-know-that-dependencies-must-firstly-be-from-a-certain-location/2875/5 "2021-03-09T03:28:36Z")
Was I able to answer your question @abd ?