The <sys/wait.h> header shall define the following symbolic
constants for use with waitpid():
WCONTINUED Report status of continued child process.
WNOHANG Do not hang if no status is available; return
immediately.
WUNTRACED Report status of stopped child process.
The <sys/wait.h> header shall define the following macros for
analysis of process status values:
WEXITSTATUS Return exit status.
WIFCONTINUED True if child has been continued.
WIFEXITED True if child exited normally.
WIFSIGNALED True if child exited due to uncaught signal.
WIFSTOPPED True if child is currently stopped.
WSTOPSIG Return signal number that caused process to stop.
WTERMSIG Return signal number that caused process to
terminate.
The <sys/wait.h> header shall define the following symbolic
constants as possible values for the options argument to
waitid():
WEXITED Wait for processes that have exited.
WNOWAIT Keep the process whose status is returned in infop
in a waitable state.
WSTOPPED Status is returned for any child that has stopped
upon receipt of a signal.
The WCONTINUED and WNOHANG constants, described above for
waitpid(), can also be used with waitid().
The type idtype_t shall be defined as an enumeration type whose
possible values shall include at least the following: P_ALL
P_PGID P_PID
The <sys/wait.h> header shall define the id_t and pid_t types as
described in <sys/types.h>.
The <sys/wait.h> header shall define the siginfo_t type and the
sigval union as described in <signal.h>.
Inclusion of the <sys/wait.h> header may also make visible all
symbols from <signal.h>.
The following shall be declared as functions and may also be
defined as macros. Function prototypes shall be provided.
pid_t wait(int *);
int waitid(idtype_t, id_t, siginfo_t *, int);
pid_t waitpid(pid_t, int *, int);
The following sections are informative.
