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).