setpgrp
if (setpgrp(0,0) < 0)
int setpgrp(pid_t _pid, pid_t _pgrp); /* obsoleted by setpgid() */
#define setsid() setpgrp(0, getpid())
setpgrp(0,0);
setpgrp(0,0);
newpgrp = setpgrp(0, getpid());
newpgrp = setpgrp();
setpgrp(0, printpid);