SNP(4)

NAME
snp - tty snoop interface.

SYNOPSIS
#include <sys/snoop.h>

DESCRIPTION
/dev/snp? are snoop devices which allow user to attach to any tty and watch activities on it. Device can be used by root only. To connect device to tty use special iocontrol SNPSTTY.Argument to it is a structure 'snptty'. struct snptty { int st_type; int st_unit; } st_type - type of tty to attach. Currently supported are : ST_PTY - pseudo-tty devices. ST_VTY - virtual ttys (syscons). ST_SIO - serial ttys. st_unit - number of tty unit. By specifying ever st_type or st_unit -1 user can detach snp device from tty. SNPGTTY - iocontrol returns current tty attached. FIONREAD - iocontrol returns ever positive value equal to number of characters in read buffer. Also special values defined: SNP_OFLOW - device overflow occured,device automatically detached. SNP_TTYCLOSE - tty still has not been attached. SNP_DETACH - snp device has been detached by user or tty device has been closed and detached automatically.

SEE ALSO
watch(8), pty(4), sio(4)

BUGS
While in line mode,user input can't be seen. Has no ability to write to attached tty device.

HISTORY
FreeBSD 2.1 by Ugen J.S.Antsilevich <ugen@NetVision.net.il>