Consider this simple program: #include <unistd.h> int main(void) { pause(); return 0; } $ ./a.out & $ truss -p `pgrep a.out` process exit, rval = 0 [1] Done ./a.out $ Surely this must be wrong. The program should have just continued running after truss was attached to it. (PR Filed under kern/114155) Cheers Michiel