Use

if (WIN32)    #do somethingendif (WIN32)

or

if (UNIX)    #do somethingendif (UNIX)

or

if (MSVC)    #do somethingendif (MSVC)

or similar

see CMake Useful Variablesand CMake Checking Platform

Given this is such a common issue, geronto-posting:

    if(UNIX AND NOT APPLE)        set(LINUX TRUE)    endif()    # if(NOT LINUX) should work, too, if you need that    if(LINUX)         message(STATUS ">>> Linux")        # linux stuff here    else()        message(STATUS ">>> Not Linux")        # stuff that should happen not on Linux     endif()

CMake boolean logic docs

CMake platform names, etc.

In General

You can detect and specify variables for several operating systems like that:

Detect Microsoft Windows

if(WIN32)    # for Windows operating system in generalendif()

Or:

if(MSVC OR MSYS OR MINGW)    # for detecting Windows compilersendif()

Detect Apple MacOS

if(APPLE)    # for MacOS X or iOS, watchOS, tvOS (since 3.10.3)endif()

Detect Unix and Linux

if(UNIX AND NOT APPLE)    # for Linux, BSD, Solaris, Minixendif()

Your specific linker issue

To solve your issue with the Windows-specific wsock32 library, just remove it from other systems, like that:

if(WIN32)    target_link_libraries(${PROJECT_NAME} bioutils wsock32)else    target_link_libraries(${PROJECT_NAME} bioutils)endif()