Detecting OS/Target when building .Net Core project (Useful when you need to DllImport different lib name by OS). Only add the following to your .csproj
<!-- OS Detection default Value -->
<PropertyGroup>
<IsWindows>False</IsWindows>
<IsOSX>False</IsOSX>
<IsAndroid>False</IsAndroid>
<IsLinux>False</IsLinux>
</PropertyGroup>
<!-- Check if we target Windows -->
<PropertyGroup Condition="($(RuntimeIdentifier.StartsWith('win')) And !$(RuntimeIdentifier.Equals('')) ) Or ( $(OS.Equals('Windows_NT')) And $(RuntimeIdentifier.Equals('')) ) ">
<!--Replacing '-' and '.' by '_' in Constants because we cannot use those characters in the source files -->
<DefineConstants>_WINDOWS_, $(RuntimeIdentifier.Replace("-","_").Replace(".","_"))</DefineConstants>
<IsWindows>True</IsWindows>
</PropertyGroup>
<!-- Check if we target OSX -->
<PropertyGroup Condition="($(RuntimeIdentifier.StartsWith('osx')) And !$(RuntimeIdentifier.Equals('')) ) Or ( $([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::OSX))) And $(RuntimeIdentifier.Equals('')) ) ">
<!--Replacing '-' and '.' by '_' in Constants because we cannot use those characters in the source files -->
<DefineConstants>_OSX_, $(RuntimeIdentifier.Replace("-","_").Replace(".","_"))</DefineConstants>
<IsOSX>True</IsOSX>
</PropertyGroup>
<!-- Check if we target Android (Doesn't Detect properly for now but is Official: https://docs.microsoft.com/en-us/dotnet/core/rid-catalog) -->
<!-- (Less check to do because we consider we cannot Dev on Android and anyway there's no way to detect an Android Platform other then the RID) -->
<PropertyGroup Condition="$(RuntimeIdentifier.StartsWith('android')) ">
<!--Replacing '-' and '.' by '_' in Constants because we cannot use those characters in the source files -->
<DefineConstants>_ANDROID_, $(RuntimeIdentifier.Replace("-","_").Replace(".","_"))</DefineConstants>
<IsAndroid>True</IsAndroid>
</PropertyGroup>
<!-- Check if we target Linux (To many name to check, instead we check if not one of the other OS) -->
<PropertyGroup Condition=" !$(IsWindows) And !$(IsOSX) And !$(IsAndroid)">
<!--Replacing '-' and '.' by '_' in Constants because we cannot use those characters in the source files -->
<DefineConstants>_LINUX_, $(RuntimeIdentifier.Replace("-","_").Replace(".","_"))</DefineConstants>
<IsLinux>True</IsLinux>
</PropertyGroup>And then you can detect the OS you are running on with C# preprocessor directives
static void Main(string[] args)
{
#if _WINDOWS_
Console.WriteLine("_WINDOWS_");
#if (_WINDOWS_ == win10_x64)
Console.WriteLine("win10_x64");
#endif
#elif _OSX_
Console.WriteLine("_OSX_");
#elif _LINUX_
Console.WriteLine("_LINUX_");
#if _LINUX_ == ubuntu_14_04_x64
Console.WriteLine("ubuntu_14_04_x64");
#elif _LINUX_ == ubuntu_16_04_x64
Console.WriteLine("ubuntu_16_04_x64");
#endif
#elif _ANDROID_
/* Doesn't Detect properly for now but is Official: https://docs.microsoft.com/en-us/dotnet/core/rid-catalog */
Console.WriteLine("_ANDROID_");
#endif
}