Question

I’m writing a makefile that has to be compatible with both LINUX and the HP-UX operating system. I’m aware that certain shell commands in LINUX are not compatible with HP-UX. Consequently, I was wondering if it was possible to have macros declared conditionally so that if it was determined that the OS was HP-UX, the macro would be defined a certain way and if the OS was LINUX, it would be defined differently?

OS       = `uname`
myOS     = Linux


ifeq ($(OS),$(myOS))
    message = "HELLO LINUX"
else
    message = "HELLO FOO" 
endif

all: install

install:
    echo $(message)

I’ve tried using the approach above; however, it seems that ifeq determines that OS and myOS are not the same. They should both be ‘Linux’, but it’s outputting the else block instead.

Answer 1

You shall use $(shell …) in order to execute a SHELL command, this will work

OS       := $(shell uname)
myOS     := Linux


ifeq ($(OS),$(myOS))
    message := "HELLO LINUX"
else
    message := "HELLO FOO" 
endif

all: install

install:
    echo $(message)