PTRAP(4) PTRAP(4)
NAME
ptrap - plumber(4) filter
SYNOPSIS
ptrap port [!]regexp [ +attr [!]regexp ... ] ...
DESCRIPTION
Ptrap is a program that mounts itself over a plumber(4) ser-
vice mounted at /mnt/plumb and filters incoming messages
according to the rules provided on the command line.
Ptrap accepts an arbitrary number of filters; each filter
applies to a port, and may match over both the data and
attributes of plumb messages.
A filter is formatted as a port name, a data filter, and a
list of attribute filters.
The data filter is a regex(6) that matches the plumbed data.
The attribute filter consists of the attribute name prefixed
with a '+', followed by a regex(6) that matches the contents
of the attribute. Any regex may be prefixed with a '!' in
order to negate a match, causing all matches for that regex
to be discarded. All parts of a filter must match in order
for a plumb message to be forwarded.
EXAMPLES
Start a sam(1) instance dedicated to editing kernel source
code:
ptrap edit '^/sys/src/9/'
sam
In another window, start a second sam(1) instance for all
other editing jobs:
ptrap edit '!^/sys/src/9/'
sam
Start an acme(1) instance instance dedicated to reading
plumbed manual pages:
ptrap edit '.*' +action '^showdata' +filename '^/man/'
acme -c1
SOURCE
/sys/src/cmd/ptrap.c
SEE ALSO
plumber(4), plumb(6)
Page 1 Plan 9 (printed 12/21/24)
PTRAP(4) PTRAP(4)
BUGS
Multiple filters specified on the same port ignore all but
the last one.
Ptrap would be more useful if it could inhibit sending the
message to other clients.
As far as plumber(4) is concerned, even messages dropped by
ptrap are "accepted", which means rules that are supposed to
apply to messages not accepted by clients are not invoked
(e.g. a rule starting an editor if no one is listening to
the edit port will not work if there is a ptrap on that
port).
HISTORY
Ptrap first appeared in 9front (February, 2018).
Page 2 Plan 9 (printed 12/21/24)