VMS Help ATTACH, Examples  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    1.$ ATTACH JONES_2

      The ATTACH command transfers the terminal's control to the
      subprocess JONES_2.

    2.$ ATTACH/IDENTIFICATION=30019

      The ATTACH command switches control from the current process
      to a process having the PID 30019. Notice that because the
      /IDENTIFICATION qualifier is specified, the process-name
      parameter is omitted.