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SNP (4) | Special files and drivers | Unix Manual Pages | :man

NAME

snp - tty snoop interface

CONTENTS

Synopsis
Description
See Also
History
Authors
Bugs

SYNOPSIS


.In 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
.Cd "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 a tty device, and then issue the SNPSTTY ioctl on snp 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 snp 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 snp 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 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

AUTHORS

BUGS


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