program [args ...]
nghook utility creates a
socket type node and connects it to hook hookname of the
node found at path. If hookname is
debug” is assumed.
-e option is given, the third
argument is interpreted as the path to a program, and this program is
executed with the remaining arguments as its arguments. Before executing,
the program Netgraph messages (specified by the
option) are sent to the node. The program is executed with its standard
input (unless closed by
-n) and output connected to
-e option is not given, all data
written to standard input is sent to the node, and all data received from
the node is relayed to standard output. Messages specified with
-m are sent to the node before the loop is entered.
nghook utility exits when
EOF is detected on standard input in this case.
The options are as follows:
- Output each packet read in human-readable decoded ASCII form instead of
- Increase the debugging verbosity level.
- Execute the program specified by the third argument.
- Loops all received data back to the hook in addition to writing it to
- Before executing the program (in
-e mode) send the
given ASCII control message to the node. This option may be given more
- Do not attempt to read any data from standard input. The
nghook utility will continue reading from the node
until stopped by a signal.
- Use file descriptor 0 for output instead of the default 1.
- Use file descriptor 1 for input instead of the default 0.
netgraph system was designed and first implemented
at Whistle Communications, Inc. in a version of FreeBSD
2.2 customized for the Whistle InterJet.
Although all input is read in unbuffered mode, there is no way to control the
packetization of the input.
If the node sends a response to a message (specified by
-m), this response is lost.