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

     nghook -- connect to a netgraph(4)	node

     nghook [-Sadlns] [-m msg] path [hookname]

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

     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 (specified
     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 send 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:

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

     -a	     Output each packet	read in	human-readable decoded ASCII form in-
	     stead 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

     -n	     Don't attempt to read any data from standard input.  The nghook
	     utility will continue reading from	the node until stopped by a

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

     Although all input	is read	in unbuffered mode, there's no way to control
     the packetization of the input.

     If	the node sends a reponse to a message (specified by -m), this response
     is	lost.

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

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

     Archie Cobbs <>

BSD			       January 19, 1999				   BSD


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