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waitid(2)

waitid(2)                        System Calls                        waitid(2)



NAME
       waitid - wait for child process to change state

SYNOPSIS
       #include <wait.h>

       int waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options);

DESCRIPTION
       The  waitid()  function  suspends  the calling process until one of its
       child processes changes state. It records the current state of a  child
       in the structure pointed to by infop. It returns immediately if a child
       process changed state prior to the call.


       The idtype and id arguments specify which children waitid() is to  wait
       for, as follows:

           o      If  idtype  is  P_PID,  waitid()  waits for the child with a
                  process ID equal to (pid_t)id.


           o      If idtype is P_PGID, waitid() waits for  any  child  with  a
                  process group ID equal to (pid_t)id.


           o      If  idtype  is P_ALL, waitid() waits for any child and id is
                  ignored.



       The options argument is used to specify which state changes waitid() is
       to wait for. It is formed by bitwise OR operation of any of the follow‐
       ing flags:

       WCONTINUED    Return the status for any child that was stopped and  has
                     been continued.


       WEXITED       Wait for process(es) to exit.


       WNOHANG       Return immediately.


       WNOWAIT       Keep the process in a waitable state.


       WSTOPPED      Wait  for and return the process status of any child that
                     has stopped upon receipt of a signal.


       WTRAPPED      Wait for traced process(es) to become trapped or reach  a
                     breakpoint (see ptrace(3C)).



       The  infop  argument must point to a siginfo_t structure, as defined in
       siginfo.h(3HEAD). If waitid() returns because a child process was found
       that  satisfies  the  conditions  indicated by the arguments idtype and
       options, then the structure pointed to by infop will be filled  by  the
       system  with the status of the process. The si_signo member will always
       be equal to SIGCHLD.


       One instance of a SIGCHLD signal is queued for each child process whose
       status  has  changed. If waitid() returns because the status of a child
       process is available and WNOWAIT was  not  specified  in  options,  any
       pending  SIGCHLD  signal  associated  with the process ID of that child
       process is discarded. Any other pending SIGCHLD signals remain pending.

RETURN VALUES
       If waitid() returns due to a change of state of one of its children and
       WNOHANG  was  not  used,  0  is returned. Otherwise, −1 is returned and
       errno is set to indicate the error. If  WNOHANG  was  used,  0  can  be
       returned  (indicating  no error); however, no children may have changed
       state if info->si_pid is 0.

ERRORS
       The waitid() function will fail if:

       ECHILD    The set of processes specified by idtype and id does not con‐
                 tain any unwaited processes.


       EFAULT    The infop argument points to an illegal address.


       EINTR     The waitid() function was interrupted due to the receipt of a
                 signal by the calling process.


       EINVAL    An invalid value was specified for options, or idtype and  id
                 specify an invalid set of processes.


USAGE
       With  options  equal  to  WEXITED | WTRAPPED, waitid() is equivalent to
       waitpid(3C). With idtype equal to P_ALL and options equal to WEXITED  |
       WTRAPPED, waitid() is equivalent to wait(3C).

ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       tab()  box; cw(2.75i) |cw(2.75i) lw(2.75i) |lw(2.75i) ATTRIBUTE TYPEAT‐
       TRIBUTE VALUE _ Interface  StabilityCommitted  _  MT-LevelAsync-Signal-
       Safe _ StandardSee standards(7).


SEE ALSO
       exec(2),    exit(2),   fork(2),   Intro(2),   pause(2),   sigaction(2),
       ptrace(3C),  signal(3C),   wait(3C),   waitpid(3C),   siginfo.h(3HEAD),
       attributes(7), standards(7)



Oracle Solaris 11.4               9 Jun 2004                         waitid(2)
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