Platform independent Makefile - Windows and WSL

Question

I am trying to write a top level Makefile that will enter a directory and use the make.exe present in it to make a target. The project is based in Eclipse on a vendor SDK(hence bundling of the make binary). I wanted to create a generic Makefile that could work on both Windows cmd and WSL (Windows linux). I have been able to kind of get it to work individually, but I am unsure how to make it work irrespective of who is using which platform to run this makefile.

For Windows, here is what worked:

all:
     cd DIR && make.exe TARGET

On WSL, I use this command:

all:
    cd DIR && ./make.exe TARGET

I had to do this as the sub makefile checks if the binary used is actually the one bundled, else throws an error. How can I make this Makefile generic?

Answer 1

You may need to have the Makefile detect which platform it's being used on and execute separate commands. Here's how you can do that.

ifeq '$(findstring ;,$(PATH))' ';'
    UNAME := Windows
else
    UNAME := $(shell uname 2>/dev/null || echo Unknown)
endif

The UNAME variable is set to Linux, Windows or Unknown. It can then be compared throughout the remainder of the Makefile to separate any OS-sensitive variables and commands.

The key is that Windows uses semicolons to separate paths in the PATH variable whereas Linux uses colons.

Of course, GNU make is required, or another make which supports the functions used.

I posted a more complete version of this solution that handles Cygwin and MSYS2 here.