waitid(2)							System Calls Manual							 waitid(2)

NAME

       waitid - Wait for child process to change state

SYNOPSIS

       #include <sys/wait.h>

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

STANDARDS

       Interfaces documented on this reference page conform to industry standards as follows:

       waitid(): XPG4-UNIX

       Refer to the standards(5) reference page for more information about industry standards and associated tags.

PARAMETERS

       Identifies  the type of process to be affected.	Used with the id parameter, it suspends execution for the specified child process.  Speci-
       fies either the process ID or process group ID of the child process.  Used with the idtype parameter, it suspends execution for the  speci-
       fied process.  Specifies a pointer to a siginfo_t structure.  Specifies the conditions that must occur before a wait operation is performed
       by the waitid() function.

DESCRIPTION

       The waitid() function holds a calling process until the state of a child process changes.  The current state of the child is recorded in  a
       structure  pointed  to  by  the	infop parameter. If a child process changed state prior to the call to the waitid() function, the waitid()
       function returns immediately.

       The idtype and id parameters determine which child process the waitid() function is to act upon.  If the idtype	parameter  is  P_PID,  the
       waitid() function waits for the child with a process ID equal to (pid_t)id.  If the idtype parameter is P_PGID, the waitid() function waits
       for any child with a process group ID equal to (pid_t)id.  If the idtype parameter is P_ALL, the waitid function waits for  any	child  and
       the id parameter is ignored.

       The options parameter specifies the conditions that must occur before a wait operation is performed by the waitid() function.  To specify a
       condition, use at least one of the following flags in a logical OR operation: Return the status for any child that was stopped and has been
       continued.   Wait  for  processes  to  exit.   Return immediately if no child processes in the requested state are present.  Keep the child
       process whose status is returned in infop in a waitable state.  Another wait for that child may occur with the same results.  Wait for  and
       return  the  process  status  of  any  child  that has stopped upon receipt of a signal.  [Tru64 UNIX]  Wait for traced processes to become
       trapped or reach a breakpoint (see ptrace(2)).

       The infop parameter must point to a siginfo_t structure as defined in siginfo(5). This structure  contains  the	status	explaining  why  a
       process is in a wait state.

       The  waitid()  function	returns if a child process is found that satisfies the conditions defined by the idtype and options parameters. In
       this case, the system fills in the structure pointed to by the infop parameter with the process status. The system always sets the si_signo
       structure member to SIGCHLD.

RETURN VALUE

       If the waitid() function returns because the state of a child process changes, it returns a value of zero (0).  Otherwise, a value of -1 is
       returned and errno is set to indicate the error.

ERRORS

       The waitid() function sets errno to the specified values for the following conditions: The calling process has no unwaited-for  child  pro-
       cesses.	 [Tru64  UNIX]	The  infop  parameter points to an invalid address.  The waitid() function was interrupted due to the receipt of a
       signal by the calling process.  An invalid value was used with the options parameter, or the idtype and id parameters  specify  an  invalid
       set of processes.

SEE ALSO

       Functions:  intro(2), exec(2), exit(2), fork(2), pause(3), ptrace(2), sigaction(2), signal(2), wait(2)

       Routines:  pause(3)

       Files:  siginfo(5)

       Standards:  standards(5)

																	 waitid(2)