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
20 are snoop devices which allow users to attach to any tty
21 and watch activities on it.
22 The kernel must be compiled with
26 module must be loaded, for these devices to be available.
30 device with a tty to be observed, open the
32 device and then use the
35 The argument passed to the ioctl is the address of a variable of type
37 To detach the snp device from a tty use a pointer to a value of
38 .Vt ( dev_t ) Ns Li -1 .
42 ioctl returns information about the current tty attached to the open
48 ioctl returns a positive value equal to the number of characters
50 Special values defined are:
51 .Bl -tag -width ".Dv SNP_TTYCLOSE"
53 device overflow occurred, device detached.
58 device has been detached by user or tty device has been closed
69 device first appeared in
72 .An Ugen J.S. Antsilevich Aq Mt ugen@NetVision.net.il
75 This manual page is horribly stale and wildly inaccurate in some places.
77 While in line mode, user input can't be seen.
78 No signals may be sent to the observed tty.