waitid(2)                 SYSTEM CALLS                  waitid(2)



NAME
     waitid - wait for child process to change state

SYNOPSIS
     #include <sys/types.h>
     #include <wait.h>
     int waitid(idtypet idtype, idt id, siginfot  *infop,  int
     options);

DESCRIPTION
     waitid suspends the calling process until one of  its  chil-
     dren changes state.  It records the current state of a child
     in the structure pointed to by infop.  If  a  child  process
     changed  state  prior  to the call to waitid, waitid returns
     immediately.

     The idtype and id arguments specify which children waitid is
     to wait for.

          If idtype is PPID, waitid waits for the child  with  a
          process ID equal to (pidt) id.

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

          If idtype is PALL, waitid waits for any  children  and
          id is ignored.

     The options argument is used to specify which state  changes
     waitid  is to wait for.  It is formed by an OR of any of the
     following flags:

     WEXITED        Wait for process(es) to exit.

     WTRAPPED       Wait for traced process(es) to become trapped
                    or reach a breakpoint [see ptrace(2)].

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

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

     WNOHANG        Return immediately.

     WNOWAIT        Keep the process in a waitable state.

     infop must point to a siginfot  structure,  as  defined  in
     siginfo(5).   siginfot  is filled in by the system with the
     status of the process being waited for.




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waitid(2)                 SYSTEM CALLS                  waitid(2)



     waitid fails if one or more of the following is true.

     EFAULT         infop points to an invalid address.

     EINTR          waitid was interrupted due to the receipt  of
                    a signal by the calling process.

     EINVAL         An invalid value was specified for options.

     EINVAL         idtype and  id  specify  an  invalid  set  of
                    processes.

     ECHILD         The set of processes specified by idtype  and
                    id   does   not   contain   any  unwaited-for
                    processes.

DIAGNOSTICS
     If waitid returns due to a change of state  of  one  of  its
     children,  a  value of 0 is returned.  Otherwise, a value of
     -1 is returned and errno is set to indicate the error.

SEE ALSO
     intro(2), exec(2), exit(2),  fork(2),  pause(2),  ptrace(2),
     signal(2),
     sigaction(2), wait(2), siginfo(5).






























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