Compile any C Program using just "make" (From a Makefile)

Question

I'm learning C Programming through "Learn C the Hard Way." I am currently (for quite a long time) on Exercise 2, which can be found here: http://c.learncodethehardway.org/book/ex2.html In the extra credit section, there is a challenge which asks us to edit the Makefile so we can compile the .c file (ex1.c) using just the command "make". This is what the challenge exactly says: Create an all: ex1 target that will build ex1 with just the command make. Through looking here and a bunch of other places, this is the code I think is correct: ``` CFLAGS="-Wall" -g all: ex1 CFLAGS="-Wall" -g clean: rm -f ex1 ``` However, when I try to run this, I get the compiled file and keep getting an error: ``` cc "-Wall" -g ex1.c -o ex1 CFLAGS="-Wall" -g /bin/sh: 1: -g: not found make: *** [all] Error 127 ``` What is happening here? What is the reason behind the error message? How can I fix this? Thanks guys.

Accepted Answer

If `all` is the first target in your makefile (I'm making a wild guess here since you've not showed the entire Makefile), make would choose that as the first target to build, when you do not pass an explicit target from the command line (i.e. mere `make`)

`ex1` is a pre-requisite for `all`, so it builds it first and hence you see the following line:

```
cc "-Wall" -g    ex1.c   -o ex1
```

After `ex1` is built, make tries to execute the recipe for all, where it executes the following command:

```
CFLAGS="-Wall" -g
```

Since `-g` by itself is not a valid command or application that can be executed in the shell, you get this error:

```
/bin/sh: 1: -g: not found
```

Solution:

You've already defined `CFLAGS` in the beginning of the makefile, so no need to define it once again in the recipe. Even if you wish to override the variable `CFLAGS`, you should not be using it directly as part of the recipe.

Define `all` and `clean` as `PHONY` targets, if you've not already done so. The target `all` and `clean` do not create a file named `all` or `clean` after the recipe is executed, so it is a good practice to classify these targets as `PHONY`.

You don't need double quotes around `-Wall`

The following Makefile has all these corrections:

```
CFLAGS = -Wall -g

all: ex1

clean:
    rm -f ex1

.PHONY: all clean
```

Compile any C Program using just "make" (From a Makefile)

Solution

Problem