       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  imme-
              diately   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 pro-
              cess. 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 contains the signal name.  If the process
              is  currently  stopped  (on  systems  that  support
              SIGSTP), the second element is `STOP', followed  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 com-
              mand is executed after the process terminates, 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  functionality  is  avail-
              able.

              This command is provided by Extended Tcl.
