WNOWAIT
WEXITED | WTRAPPED | WSTOPPED | WCONTINUED | WNOWAIT) != 0)
(void) waitid(P_PID, pid, &info, WEXITED | WNOWAIT);
ret = waitpid(pid, &stat, wflags|WNOWAIT);
~(WEXITED|WTRAPPED|WSTOPPED|WCONTINUED|WNOHANG|WNOWAIT))
if (arg & WNOWAIT)
if ((pid = waitpid(child_pid, &status, WNOHANG|WNOWAIT)) != -1) {
#define WOPTMASK (WEXITED|WTRAPPED|WSTOPPED|WCONTINUED|WNOHANG|WNOWAIT)
int waitflag = !(options & WNOWAIT);
(options & ~WNOWAIT) == (WNOHANG | WEXITED) &&
#define WOPTMASK (WEXITED|WTRAPPED|WSTOPPED|WCONTINUED|WNOHANG|WNOWAIT)