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50 lines
1.5 KiB
Groff
50 lines
1.5 KiB
Groff
.Dd Februar 17, 1995
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.Dt SNP(4)
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.Os
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.Sh NAME
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snp - tty snoop interface.
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.Sh SYNOPSIS
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#include <sys/snoop.h>
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.Sh DESCRIPTION
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/dev/snp? are snoop devices which allow user to attach to any tty
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and watch activities on it. Device can be used by root only.
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To connect device to tty use special iocontrol SNPSTTY.Argument to
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it is a structure 'snptty'.
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struct snptty {
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int st_type;
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int st_unit;
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}
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st_type - type of tty to attach. Currently supported are :
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ST_PTY - pseudo-tty devices.
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ST_VTY - virtual ttys (syscons).
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ST_SIO - serial ttys.
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st_unit - number of tty unit.
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By specifying ever st_type or st_unit -1 user can detach snp
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device from tty.
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SNPGTTY - iocontrol returns current tty attached.
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FIONREAD - iocontrol returns ever positive value equal to number of
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characters in read buffer. Also special values defined:
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SNP_OFLOW - device overflow occured,device automatically
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detached.
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SNP_TTYCLOSE - tty still has not been attached.
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SNP_DETACH - snp device has been detached by user or
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tty device has been closed and detached
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automatically.
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.Sh SEE ALSO
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watch(8), pty(4), sio(4)
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.Sh BUGS
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While in line mode,user input can't be seen.
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Has no ability to write to attached tty device.
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.Sh HISTORY
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FreeBSD 2.1 by Ugen J.S.Antsilevich <ugen@NetVision.net.il>
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