Langue: en

Autres versions - même langue

Version: 300479 (debian - 07/07/09)

Section: 4 (Pilotes et protocoles réseau)

BSD mandoc


snp - tty snoop interface


In sys/snoop.h Ft int Fn ioctl fd SNPSTTY &dev Ft int Fn ioctl fd SNPGTTY &dev Ft int Fn ioctl fd FIONREAD &result


/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:

device overflow occurred, device detached.
tty not attached.
device has been detached by user or tty device has been closed and detached.


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


The device first appeared in Fx 2.1 .


An Ugen J.S. Antsilevich Aq


Caveat emptor! This manual page is horribly stale and wildly inaccurate in some places.

While in line mode, user input cannot be seen. No signals may be sent to the observed tty.