regarding using env variable

From: invincible (
Date: 03/24/05

Date: Thu, 24 Mar 2005 15:44:01 +0530


I have program

void main()
    #ifdef env_var
        printf(" I am in Linux");

I am using solaris and Linux platform to compile this code. When
i run it on solaris I sould not get any message. But when i run it on
linux i should get "I am in Linux".

This one I can achieve using -dLinux while compiling it on linux

But I dont want to use any variables , is there any inbuilt environment var
which i can use for my required task.