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c++makefilecompilationgnu-makecompiler-flags

Append compiler flags when running make

I would like to append flags to the compiler flags when running make, without altering the Makefile in anyway, e.g.

make CXX_FLAGS+='-DDEBUG'

The above treats "+=" as "=", so it's not the correct symbol.

Solution

  • You just have to modify the variable as override in your Makefile once. And then you can do what you want to do.

    Here's the example,

    Makefile:

    override CFLAGS+=-g                                                                                    

app: main.c
  gcc $(CFLAGS) -o app main.c

    Run the make:

    $ make
gcc -g -o app main.c

    Append the '-Wall' to $CFLAGS from the command:

    $ make CFLAGS=-Wall
gcc -Wall -g -o app main.c

    Work fine here. And here's manual you can reference.