Quick program to fetch the current FSEventUUID for boot device on macOS

getFSEventUUID.m

#import <Foundation/Foundation.h>
#include <sys/param.h>
#include <sys/mount.h>

// adapted from http://www.cocoabuilder.com/archive/cocoa/203717-looking-for-sample-code-to-read-uuid-from-disk-volume.html
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        
        struct statfs stat;
        NSString* path = [[@"~" stringByExpandingTildeInPath] stringByStandardizingPath];
        if (statfs([[NSFileManager defaultManager] fileSystemRepresentationWithPath:path],&stat)!=0)
        {
            printf("statfs error %d",errno);
            return errno;
        }
        dev_t device = stat.f_fsid.val[0];
        
        CFUUIDRef uuid = FSEventsCopyUUIDForDevice(device);
        CFStringRef uuidStr = CFUUIDCreateString(nil,uuid);
        CFRelease(uuid);        // CF copy rule
        printf("%s",CFStringGetCStringPtr(uuidStr, kCFStringEncodingASCII));
        
     }
    return 0;
}