NGHOOK(8)		  BSD System Manager's Manual		     NGHOOK(8)

NAME
     nghook — connect to a netgraph(4) node

SYNOPSIS
     nghook [-adlnSs] [-m msg] path [hookname]
     nghook -e [-n] [-m msg] path hookname program [args ...]

DESCRIPTION
     The nghook utility creates a ng_socket(4) socket type node and connects
     it to hook hookname of the node found at path.  If hookname is omitted,
     “debug” is assumed.

     If the -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 (spec‐
     ified by the -m option) are sent to the node.  The program is executed
     with its standard input (unless closed by -n) and output connected to the
     hook.

     If the -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.  The nghook utility exits when EOF is detected on standard
     input in this case.

     The options are as follows:

     -a      Output each packet read in human-readable decoded ASCII form
	     instead of raw binary.

     -d      Increase the debugging verbosity level.

     -e      Execute the program specified by the third argument.

     -l      Loops all received data back to the hook in addition to writing
	     it to standard output.

     -m msg  Before executing the program (in -e mode) send the given ASCII
	     control message to the node.  This option may be given more than
	     once.

     -n      Do not attempt to read any data from standard input.  The nghook
	     utility will continue reading from the node until stopped by a
	     signal.

     -S      Use file descriptor 0 for output instead of the default 1.

     -s      Use file descriptor 1 for input instead of the default 0.

SEE ALSO
     netgraph(3), netgraph(4), ngctl(8)

HISTORY
     The netgraph system was designed and first implemented at Whistle Commu‐
     nications, Inc. in a version of FreeBSD 2.2 customized for the Whistle
     InterJet.

AUTHORS
     Archie Cobbs ⟨archie@whistle.com⟩

BUGS
     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.

BSD			       October 24, 2003 			   BSD