Add RELEASE file and define version strings.

Makefile

+CC = $(CROSS)$(TARGET)gcc
+
+BUILD_ID = $(shell date +%F_%R)
+VERSION = $(shell cat RELEASE)
+GIT_VER = $(shell git describe --tags --dirty --always 2>/dev/null)
+ifeq "$(GIT_VER)" ""
+GIT_VER = "release"
+endif
+
+CFLAGS_BUILD = -DBUILD_ID=\"$(BUILD_ID)\" -DVERSION=\"$(VERSION)\" -DGIT_VER=\"$(GIT_VER)\"
+
 CFLAGS_DBG?=	-ggdb
 CFLAGS_OPT?=	-O2
 CFLAGS_WARN?=	-Wall -W -Wextra -Wshadow -Wformat-security \
 		-Wredundant-decls -Wstrict-prototypes
 
 CFLAGS?=	${CFLAGS_DBG} ${CFLAGS_OPT}
-CFLAGS+=	${CFLAGS_WARN}
+CFLAGS+=	${CFLAGS_WARN} ${CFLAGS_BUILD}
 
 CFLAGS+=	`pkg-config --cflags fuse`
 LIBS+=		`pkg-config --libs fuse`

RELEASE

+1.0

fjfs.c

 #include <fnmatch.h>
 #include <fuse.h>
 
+static const char *program_id = "fjfs v" VERSION " (" GIT_VER ", build " BUILD_ID ")";
+
 /* Handle list of files */
 struct fileinfo {
 	int		fd;
 };
 
 static void show_usage(void) {
-	printf("fjfs - FUSE module for virtual joining of multiple files into one.\n");
+	printf("%s\n", program_id);
+	printf("FUSE module for virtual joining of multiple files into one.\n");
 	printf("\n");
 	printf("Usage: fjfs [file-list-options] [options] mount-point-file file-list\n");
 	printf("\n");