CMake best practice for library install

问题

I am trying an install script for a shared library with cmake. While I found out that I want to use install, I am not sure what's the best practice to set the destinations.

This comment* and various bugreports refer to LIB_INSTALL_DIR.

However I find hardly any documentation of the LIB_INSTALL_DIR

My best guess for a library install would be:

add_library(mylib SHARED ${sources})
install(TARGET mylib LIBRARY DESTINATION ${LIB_INSTALL_DIR})
install(FILES ${libheaders} DESTINATION ${??})

My questions regarding this are:

1. How do I set LIB_INSTALL_DIR in a way that the user can overwrite it if requires (set LIB_INSTALL_DIR lib) does not allow this, does it?)
2. What is the correct variable for the header directory? (Should I try to default it (set it to that if it is undefined) to CMAKE_SYSTEM_INCLUDE_PATH, and if so how do I do that?)
3. install(TARGET has a INCLUDES DESTINATION, is there a better way than using manual install(FILES ${libheaders} DESTINATION ${??}) for a bunch of headers?

*first comment, by Fraser, could not find a way to link directly to the comment, only to the answer.

来源：https://stackoverflow.com/questions/36723588/cmake-best-practice-for-library-install