The makefile environment variables are part of the GNU make(3) utility. These can be used to set the variables needed in your makefile. The variables can also be used by the shell(1) built-in command.
The variables are found in the makefile section of the Makefiles page. They are not standard GNU make variables, but rather GNU make variables. They are not defined by make but by the system.
Makefiles are just a standard GNU make file that makes use of the variables available in the makefile.
The makefiles are set in the Makefile.pre.in file. They are used by the shell and the make command so that if the shell is set up to use special variables, the makefile can use these variables.
So now, you know that you can set environment variables in the shell. But you might not know why you need to. And you might not be able to find a guide to setting these special variables. I’m going to talk about these variables here.
This section is the most important part of this article because it goes into very specific details about the makefile’s use of environment variables. The first thing to note is that the shell sets the variables. The shell also makes the code that uses the variables, like the main function, read the variables from the environment. So if we start the shell by typing $, we’ll have the shell set up the variables to use makefiles.
The first thing we want to do is set up the variable PATH by typing PATH=/bin. So for instance if we want the shell to find all the commands in our directory called bin, we type PATH=. Then we type./bin to run the command that will run our program. So the PATH variable holds our entire environment, and the program that will run it.
I don’t know about you, but I like to leave the PATH variable set to the same value that I set in my shell, just to be clear. That way in the future if I ever find that I need my shell to look for programs in a different directory, I can just change it to the directory that I want it to look in. I don’t want to have to remember the path to the files I need to look in.
A lot of times, people use environment variables to control what programs they run, or even to be able to run a command that requires another program. It’s a bit of a kludge, but one thing that I have found useful in programming, and the reason it’s useful in our lives, is that when you’re not using the command line, it’s easy to make your programs run a certain way. It’s almost like you’re running them in a shell.
If you’re not using the command line, you are actually running them in a command window. You can use the “make” command to create a command window, and then you can use a variable to tell it what to do with it. I find the best way to do this is with a makefile.