DragonFly On-Line Manual Pages


SNP(4)		      DragonFly Kernel Interfaces Manual		SNP(4)

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 snp module must be loaded, for these devices to be available. To associate a given snp device with a tty to be observed, open the snp device and then use the SNPSTTY ioctl. The argument passed to the ioctl is the address of a variable of type dev_t. To detach the snp device from a tty use a pointer to a value of (dev_t)-1. The SNPGTTY ioctl returns information about the current tty attached to the open snp device. The FIONREAD ioctl returns a positive value equal to the number of char- acters in a read buffer. Special values defined are: SNP_OFLOW device overflow occurred, device detached. SNP_TTYCLOSE tty not attached. SNP_DETACH snp device has been detached by user or tty device has been closed and detached.

SEE ALSO

pty(4), sio(4), kldload(8), watch(8)

HISTORY

The snp device first appeared in FreeBSD 2.1.

AUTHORS

Ugen J.S. Antsilevich <ugen@NetVision.net.il>

BUGS

Caveat emptor! This manual page is horribly stale and wildly inaccurate in some places. While in line mode, user input can't be seen. No signals may be sent to the observed tty. DragonFly 3.7 February 24, 1995 DragonFly 3.7