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Clean up man page

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Paul Traina 1995-02-23 01:25:48 +00:00
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share/man/man4/snp.4
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@ -1,49 +1,80 @@
.Dd Februar 17, 1995
.Dt SNP(4)
.Os
.\"
.\" @(#)snp.4 1.1 (FreeBSD) 2/17/95
.\"
.Dd February 17, 1995
.Dt SNP 4
.Os FreeBSD
.Sh NAME
snp - tty snoop interface.
.Nm snp
.Nd tty snoop interface
.Sh SYNOPSIS
#include <sys/snoop.h>
.Fd #include <sys/ioctl.h>
.Fd #include <sys/snoop.h>
.Ft int
.Fn ioctl fd SNPSTTY &snptty
.Ft int
.Fn ioctl fd SNPGTTY &snptty
.Ft int
.Fn ioctl fd FIONREAD 0
.Sh DESCRIPTION
/dev/snp? are snoop devices which allow user to attach to any tty
and watch activities on it. Device can be used by root only.
To connect device to tty use special iocontrol SNPSTTY.Argument to
it is a structure 'snptty'.
struct snptty {
int st_type;
int st_unit;
}
/dev/snp? are snoop devices which allow user to attach to any tty
and watch activities on it.
st_type - type of tty to attach. Currently supported are :
ST_PTY - pseudo-tty devices.
ST_VTY - virtual ttys (syscons).
ST_SIO - serial ttys.
To associate a given
.Nm snp
device with a tty to be observed, open the
.Nm snp
device and then use the SNPSTTY ioctl.
The argument passed to the IOCTL is the address of a structure of
the following type:
.Bd -literal -ffset indent
struct snptty {
int st_type; /* type of the tty to attach */
int st_unit; /* number of the tty unit */
}
st_unit - number of tty unit.
By specifying ever st_type or st_unit -1 user can detach snp
device from tty.
SNPGTTY - iocontrol returns current tty attached.
FIONREAD - iocontrol returns ever positive value equal to number of
characters in read buffer. Also special values defined:
SNP_OFLOW - device overflow occured,device automatically
detached.
SNP_TTYCLOSE - tty still has not been attached.
SNP_DETACH - snp device has been detached by user or
tty device has been closed and detached
automatically.
#define ST_PTY 0 /* regular pty */
#define ST_VTY 1 /* syscons vty */
#define ST_SIO 2 /* serial lines */
.Ed
.Pp
By setting st_type or st_unit to -1, the user may detach the snp device
for a tty.
.Pp
The SNPGTTY ioctl returns information about the current tty attached to
the open
.Nm snp
device.
.Pp
The FIONREAD ioctl returns a positive value equal to the number of characters
in a read buffer.
Special values defined are:
.Bl -tag -width SNP_TTYCLOSE
.It Dv SNP_OFLOW
device overflow occured, device detatched.
.It Dv SNP_TTYCLOSE
tty not attached.
.It Dv SNP_DETACH
.Nm snp
device has been detatched by user or tty device has been closed
and detatched.
.Sh SEE ALSO
watch(8), pty(4), sio(4)
.Xr watch 8 ,
.Xr pty 4 ,
.Xr sio 4
.Sh RESTRICTIONS
Only the superuser may access the
.Nm snp
devices.
.Sh BUGS
While in line mode,user input can't be seen.
Has no ability to write to attached tty device.
While in line mode, user input can't be seen.
.Nm
snp
is a read-only device, there is no ability to write to attached tty device.
.Sh AUTHOR
Ugen J.S. Antsilevich <ugen@NetVision.net.il>
.Sh HISTORY
FreeBSD 2.1 by Ugen J.S.Antsilevich <ugen@NetVision.net.il>
The
.Nm
snp
device first appeared in FreeBSD 2.1.