How can I make my program print its github version number with BSD?

Question

I want to be able to use a variable in my code that is the git version. If I set the variable with make and then override it in a .h file then the final value that prints wil lbe from the '.h' file. Is there a way to override the .h from the makefile?

 executing make
gcc -O2 -pipe   -pedantic -std=c99 -Wall -O3 -ledit -DVERSION=\"\" -c main.c -o main.o
In file included from main.c:9:0:
openshell.h:17:0: warning: "VERSION" redefined [enabled by default]
 #define VERSION "v0.1a"

I'm trying to set my variable VERSION from github so that a version can be viewed:

$ ./a.out --version
OpenShell version 0.1(a)
Version: v0.1a-2-gc6b1-dirty

I have this makefile

CC = gcc
GIT_VERSION := $(shell git describe --abbrev=4 --dirty --always --tags)
CFLAGS := $(CFLAGS) -pedantic -std=c99 -Wall -O3 -ledit -g -DVERSION=\"$(GIT_VERSION)\"

shell: main.o
    $(CC) -o shell main.o errors.c util.c pipeline.c -ledit

main.o: main.c errors.c util.c

.PHONY: clean
clean:
    rm -f *.o

Then it works on Linux Ubuntu but it doesn't work on BSD, with PC-BSD the variable is not shown:

dac:/usr/home/dac/openshell $ make
The Command is: make
27152: executing make
gcc -O2 -pipe   -pedantic -std=c99 -Wall -O3 -ledit -DVERSION=\"\" -c main.c -o main.o
main.c: In function 'trimstring':
main.c:116:9: warning: value computed is not used [-Wunused-value]
         *tmp++;
         ^
main.c:119:17: warning: comparison between pointer and integer [enabled by default]
     while (*tmp != NULL) {
                 ^
main.c: In function 'exec_program':
main.c:444:9: warning: implicit declaration of function 'snprintf' [-Wimplicit-function-declaration]
         snprintf(shell_prompt, sizeof(shell_prompt), "%s:%s $ ", getenv("USER"), getcwd(NULL, 1024));
         ^
main.c:444:9: warning: incompatible implicit declaration of built-in function 'snprintf' [enabled by default]
gcc -o shell main.o errors.c util.c pipeline.c -ledit
dac:/usr/home/dac/openshell $ ./shell --version
The Command is: ./shell --version
27181: executing ./shell
OpenShell version 0.1(a)
Version: 
dac:/usr/home/dac/openshell $ 

Update 160426 07:49 CET

Now it works with Ubuntu (but maybe dangerous deleting the old version number in the .h file) `GIT:= $(shell head -n -1 openshell.h > temp.txt ; mv temp.txt openshell.h;git describe --abbrev=4 --dirty --always --tags > VERSION; echo "#define VERSION \"$(GIT_VERSION)\"" >> openshell.h)

The updated Makefile is now:

CC = gcc
GIT_VERSION := $(shell git describe --abbrev=4 --dirty --always --tags)
CFLAGS := $(CFLAGS) -L/usr/local/include/ -L/usr/include -pedantic -std=c99 -Wall -O3 -g -DVERSION=\"$(GIT_VERSION)\" -ledit -lncurses

LDIRS = -L/usr/local/lib -L/usr/lib
LIBS = -ledit lncurses -lcurses

shell: main.o
    $(CC) -o shell main.o errors.c util.c pipeline.c -ledit -lncurses -lcurses

main.o: main.c errors.c util.c
USERNAME := $(shell whoami >> username.txt)
GIT:= $(shell head -n -1 openshell.h > temp.txt ; mv temp.txt openshell.h;git describe --abbrev=4 --dirty --always --tags > VERSION; echo "\#define VERSION \"$(GIT_VERSION)\"" >> openshell.h)

.PHONY: clean
clean:
    rm -f *.o

`

Answer 1

To avoid warning: "VERSION" redefined, wrap the #define with #ifndef:

#ifndef VERSION
  #define VERSION "v0.1a"
#endif