WATCHER(1)                                             WATCHER(1)

     NAME
          watcher - octopus watcher for network resource arrival and
          departure

     SYNOPSIS
          watcher [ -dv ] [ -r regdir ]

     DESCRIPTION
          Watcher watches out the registry to detect and notify of
          arrivals and departures of terminals in the octopus. It
          opens /mnt/registry/event to detect changes in the registry
          (or uses the registry mounted at regdir when -r is given)
          and scans the registry each time it changes.

          For each new entry in the registry with value ofs for the
          name attribute watcher plumbs a message notifying of the
          arrival of the terminal whose name is reported by the sys
          attribute as found in the entry. When such entry is gone
          (either due to lack of refresh or due to removal from the
          registry) watcher plumbs a message notifying the departure
          of the terminal. Messages are plumbed both via plumber(8)
          and via ports(4).

          Upon departure of a terminal, as reflected by a gone reg-
          istry entry for ofs, watcher kills the entire process group
          of the process whose PID was reported in the pid attribute
          of the ofs entry. This is done to force all resources
          imported from a (no longer working) gone terminal to be dis-
          carded. Also, watcher tries to unmount the terminal from
          /devs (just in case).

          Flag -v makes the program a little verbose, to report
          arrivals and departures. Flag -d makes the program quite
          verbose, for debugging.

     SOURCE
          /usr/octopus/port/watcher.b

     SEE ALSO
          netget(1), mux(4).