Интерактивная система просмотра системных руководств (man-ов)
snp (4)
>> snp (4) ( FreeBSD man: Специальные файлы /dev/* )
BSD mandoc
NAME
snp
- tty snoop interface
SYNOPSIS
#include <sys/snoop.h> int
ioctl (fd SNPSTTY &dev); int
ioctl (fd SNPGTTY &dev); int
ioctl (fd FIONREAD &result);
DESCRIPTION
/dev/snp?
are snoop devices which allow users to attach to any tty
and watch activities on it.
The kernel must be compiled with
device snp
or the
module must be loaded,
for these devices to be available.
To associate a given
device with a tty to be observed, open the
device and a tty device, and then issue the
SNPSTTY
ioctl on
device.
The argument passed to the
ioctl(2)
is the address of a variable of type
Vt int ,
holding the file descriptor of a tty device.
To detach the
device from a tty use a pointer to a value of
-1.
The
SNPGTTY
ioctl returns information about the current tty attached to
the open
device.
The
FIONREAD
ioctl returns a positive value equal to the number of characters
in a read buffer.
Special values defined are:
SNP_OFLOW
device overflow occurred, device detached.
SNP_TTYCLOSE
tty not attached.
SNP_DETACH
device has been detached by user or tty device has been closed
and detached.
