wait(2)                          UNIX System V                          wait(2)


NAME
      wait - wait for child process to stop or terminate

SYNOPSIS
      #include <sys/types.h>
      #include <sys/wait.h>

      pid_t wait(int *stat_loc);

DESCRIPTION
      wait suspends the calling process until one of its immediate children
      terminates or until a child that is being traced stops because it has
      received a signal.  The wait system call will return prematurely if a
      signal is received.  If all child processes stopped or terminated prior
      to the call on wait, return is immediate.

      If wait returns because the status of a child process is available, it
      returns the process ID of the child process.  If the calling process had
      specified a non-zero value for stat_loc, the status of the child process
      will be stored in the location pointed to by stat_loc.  It may be
      evaluated with the macros described on wstat(5).  In the following,
      status is the object pointed to by stat_loc:

            If the child process stopped, the high order 8 bits of status will
            contain the number of the signal that caused the process to stop
            and the low order 8 bits will be set equal to WSTOPFLG.

            If the child process terminated due to an exit call, the low order
            8 bits of status will be 0 and the high order 8 bits will contain
            the low order 8 bits of the argument that the child process passed
            to exit; see exit(2).

            If the child process terminated due to a signal, the high order 8
            bits of status will be 0 and the low order 8 bits will contain the
            number of the signal that caused the termination. In addition, if
            WCOREFLG is set, a ``core image'' will have been produced; see
            signal(2).

      If wait returns because the status of a child process is available, then
      that status may be evaluated with the macros defined by wstat(5).

      If a parent process terminates without waiting for its child processes to
      terminate, the parent process ID of each child process is set to 1.  This
      means the initialization process inherits the child processes; see
      intro(2).

      wait will fail if one or both of the following is true:

      ECHILD         The calling process has no existing unwaited-for child
                     processes.




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wait(2)                          UNIX System V                          wait(2)


      EINTR          The function was interrupted by a signal.

SEE ALSO
      exec(2), exit(2), fork(2), intro(2), pause(2), ptrace(2), signal(2),
      signal(5), wstat(5).

NOTES
      See NOTES in signal(2).

      If SIGCLD is held, then wait does not recognize death of children.

DIAGNOSTICS
      If wait returns due to a stopped or terminated child process, the process
      ID of the child is returned to the calling process.  Otherwise, a value
      of -1 is returned and errno is set to indicate the error.







































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