job control in Sys V

[gwyn at BRL-VLD.ARPA]

From:      Doug Gwyn (VLD/VMB) <gwyn at BRL-VLD.ARPA>

UNIX System V Release 2 provides a form of job control, but it differs
significantly from Berkeley's:

- Uses "sxt" pseudo-devices (like pty's but better)
- Obtained by running "shl" (shell layers) program
- Layers are transparent to applications
- No signals are involved
- Apparently applications cannot determine the "shl" activity (so that
  for example a screen editor will not be able to automatically refresh
  the display when the editor job is reactivated)

Not available on the PDP-11/70, according to the SRD.