setpgrp
setpgrp(0, 0); /* if setpgid isn't available, setpgrp
setpgrp();
setpgrp();
#define setsid() setpgrp(0, getpid())
if (setpgrp(0,0) < 0)
int setpgrp(pid_t, pid_t); /* obsoleted by setpgid() */
setpgrp(0,0);
setpgrp(0,0);
ATF_REQUIRE_EQ(0, setpgrp(0, 0));
ATF_REQUIRE_EQ(-1, setpgrp(-1, -1));