       wait ?-nohang? ?-untraced? ?-pgroup? ?pid?
              Waits for a process created with the execl command to terminate,
              either due to an untrapped signal or call to exit  system  call.
              If  the  process id pid is specified, they wait on that process,
              otherwise wait on any child process to terminate.

              If -nohang is specified, then don't block waiting on  a  process
              to terminate.  If no process is immediately available, return an
              empty list.  If -untraced is specified then the status of  child
              processes  that  are  stopped, and whose status has not yet been
              reported since they stopped, are also returned.  If  -pgroup  is
              specified  and  pid  is  not  specified,  then wait on any child
              process whose process groupd ID is  they  same  as  the  calling
              process.  If pid is specified with -pgroup, then it is take as a
              process group ID, waiting on any process in that  process  group
              to terminate.

              Wait returns a list containing three elements: The first element
              is the process id  of  the  process  that  terminated.   If  the
              process  exited  normally, the second element is `EXIT', and the
              third contains the numeric exit code.  If the process terminated
              due to a signal, the second element is `SIG', and the third con-
              tains the signal name.  If the process is currently stopped  (on
              systems that support SIGSTP), the second element is `STOP', fol-
              lowed by the signal name.

              Note that it is possible to wait on processes to terminate  that
              were  create  in the background with the exec command.  However,
              if any other exec command is executed after the  process  termi-
              nates,  then  the process status will be reaped by the exec com-
              mand and will not be available to the wait command.

              On  systems  without  the  waitpid  system  call,  the  -nohang,
              -untraced  and  -pgroup  options  are  not available.  The infox
              have_waitpid command maybe use to determine if this  functional-
              ity is available.
