Added example of how to tell various FreeBSD versions apart.

1 files changed, 17 insertions, 0 deletions

diff --git a/share/examples/FreeBSD_version/FreeBSD_version.c b/share/examples/FreeBSD_version/FreeBSD_version.c
new file mode 100644
index 0000000..e9d8c76
--- /dev/null
+++ b/share/examples/FreeBSD_version/FreeBSD_version.c
@@ -0,0 +1,17 @@
+#if __FreeBSD__ == 0		/* 1.0 did not define __FreeBSD__ */
+#define __FreeBSD_version 199401
+#elif __FreeBSD__ == 1		/* 1.1 defined it to be 1 */
+#define __FreeBSD_version 199405
+#else				/* 2.0 and higher define it to be 2 */
+#include <osreldate.h>		/* and this works */
+#endif
+
+int main(void) { 
+  extern int getosreldate(void);
+  printf("Compilation release date: %d\n", __FreeBSD_version);
+#if __FreeBSD_version >= 199408
+  printf("Execution environment release date: %d\n", getosreldate());
+#else
+  printf("Execution environment release date: can't tell\n");
+#endif
+}