Checks the status of the child process before exiting. A child
    process is terminated when the parent process terminates.

    Format

      #include  <wait.h>

      pid_t wait  (int *status);

1 - Argument

 status

    The address of a location to receive the final status of the
    terminated child. The child can set the status with the exit
    function and the parent can retrieve this value by specifying
    status.

2 - Description

    The wait function suspends the parent process until the final
    status of a terminated child is returned from the child.

    On OpenVMS Version 7.0 and higher systems, the wait function is
    equivalent to waitpid( 0, status, 0 ) if you include <wait.h> and
    compile with the _POSIX_EXIT feature-test macro set (either with
    /DEFINE=_POSIX_EXIT or with #define _POSIX_EXIT at the top of
    your file, before any file inclusions).

3 - Return Values

    x                  The process ID (PID) of the terminated child.
                       If more than one child process was created,
                       wait will return the PID of the terminated
                       child that was most recently created.
                       Subsequent calls will return the PID of the
                       next most recently created, but terminated,
                       child.
    -1                 No child process was spawned.