Using CMake to create an executable that can run independently on other machines - c++

Question

I’m using LibTorch and OpenCV for a program in Cpp. The compilation and building is done on Linux using CMake. The program builds and runs as expected.
I want to use the executable that CMake created on another Linux machine.
The problem is that I don’t want to install either LibTorch nor OpenCV on the other machine. I’d rather supply the user with a single executable if possible.
How can CMake create a single independent executable?
If making just a single file is irrelevant, how can CMake copy all needed libraries to a single directory?
The current CMake file:
cmake_minimum_required(VERSION 2.8)
project(prediction)
list(APPEND CMAKE_PREFIX_PATH “libtorch”) # the folder where libtorch in found
set(CMAKE_BUILD_TYPE Release)
find_package( OpenCV REQUIRED )
find_package( Torch REQUIRED )
if(NOT Torch_FOUND)
message(FATAL_ERROR “Pytorch Not Found!”)
endif(NOT Torch_FOUND)
message(STATUS “Pytorch status:”)
message(STATUS " libraries: ${TORCH_LIBRARIES}")
message(STATUS “OpenCV library status:”)
message(STATUS " version: ${OpenCV_VERSION}")
message(STATUS " libraries: ${OpenCV_LIBS}")
message(STATUS " include path: ${OpenCV_INCLUDE_DIRS}")
file(GLOB SOURCES ".h" ".cpp") # Link all headers and sources in root dir
include_directories( ${OpenCV_INCLUDE_DIRS} )
add_executable(entrypoint ${SOURCES})
target_link_libraries(entrypoint ${TORCH_LIBRARIES} ${OpenCV_LIBS})
set_property(TARGET entrypoint PROPERTY CXX_STANDARD 14)
####### EDIT
Thanks for the answers.
Following Phesho_T answer bellow, I got the static compilation of LibTorch, but it won't compile with the set() instruction. It throws C10_LIBRARY NOTFOUND.
I think I'll try to use the shared libraries. How can CMake be instructed to copy the releveant shared libraries to the "build" folder, so I can pack everything in a .zip file and send it to the user.

Answer 1

Like another answer said, you need to link the static libs of Torch and OpenCV in your executable.
There are a few pre-requisites for this:
The two libraries need to have static (.a) libraries installed on your system. If they don't, you may have to manually build them. Steps for this differ between different packages.
You need to tell CMake to search for the static libraries ONLY. This is done via the CMAKE_FIND_LIBRARY_SUFFIXES variable. The chances are the default for this is .so;.a, meaning it will find the shared library first.
set(CMAKE_FIND_LIBRARY_SUFFIXES ".a")
The fact that you're using variables in your target_link_libraries command, instead of imported libraries (the modern CMake way) makes me think that this should be enough - these variables should expand to full paths to the static libraries, which should then be added to your linker command.
Things are a bit more complicated to explain if imported targets were used, but this might be out-of-scope for this question.
Try it out and let us know how you get on.

Answer 2

To create a single executable you need to statically link the dependencies into your executable. Check your libraries to see if they provide static-libs else you need to recompile libtorch or opencv to make static libraries.