2 .\" $FreeBSD: src/share/man/man4/snp.4,v 1.15.2.6 2002/08/03 12:04:15 schweikh Exp $
9 .Nd tty snoop interface
13 .Fn ioctl fd SNPSTTY &dev
15 .Fn ioctl fd SNPGTTY &dev
17 .Fn ioctl fd FIONREAD &result
19 /dev/snp? are snoop devices which allow users to attach to any tty
20 and watch activities on it.
21 The kernel must be compiled with
25 device must be loaded,
26 for these devices to be available.
30 device with a tty to be observed, open the
32 device and then use the SNPSTTY ioctl.
33 The argument passed to the ioctl is the address of a variable of type
35 To detach the snp device from a tty use a pointer to a value of (dev_t)-1.
37 The SNPGTTY ioctl returns information about the current tty attached to
42 The FIONREAD ioctl returns a positive value equal to the number of characters
44 Special values defined are:
45 .Bl -tag -width SNP_TTYCLOSE
47 device overflow occurred, device detached.
52 device has been detached by user or tty device has been closed
62 This manual page is horribly stale and wildly inaccurate in some places.
64 While in line mode, user input can't be seen.
65 No signals may be sent to the observed tty.
67 .An Ugen J.S. Antsilevich Aq ugen@NetVision.net.il
71 device first appeared in