.Dd December 10, 1993
.Dt COMCONTROL 8
.Os FreeBSD
.Sh NAME
.Nm comcontrol
.Nd "control the bidirectional status of a sio port and waiting time after DTR drop"
.Sh SYNOPSIS
.Nm comcontrol
.Ar sio_special_device
.Op Cm bidir | Fl bidir
.Op Cm dtrwait Ar ticks
.Sh DESCRIPTION
.Nm Comcontrol
is used to examine and modify the bidirectional status
of a specified
sio communications port
and its waiting time after DTR drop.
By default (if
.Ar sio_special_device
only specified),
.Nm comcontrol
will print the current port state
(if kernel was built with
.Cm options COM_BIDIR )
as either
.Cm bidir
to indicate that bidirectional operation is enabled or
.Fl bidir
to indicate that it is disabled, string
.Cm dtrwait
and current waiting time in ticks
after DTR drop.
To modify the status of the port or waiting time, simply
specify the desired new state
and/or new waiting time
on the command line.  All users with
read access to the
.Ar sio_special_device
can use
.Nm comcontrol
to get the port's status and current waiting time.
Only root can set a port's status and waiting time.
By default, each port is initially unidirectional, waiting time is
2 seconds.
.Pp
The standard way to use
.Nm comcontrol
is to put invocations of it in the
.Ar /etc/rc.local
startup script.
.Sh SEE ALSO
.Xr sio 4
.Sh FILES
.Bl -tag -width Pa
.It Pa /dev/ttyd?
.Sh DIAGNOSTICS
.Cm TIOCMSBIDIR: Inappropriate ioctl for device.
.Pp
This indicates attempt to change port status on
a non-sio special device file,
or the kernel has not been built with
.Cm options COM_BIDIR .
For more information concerning reconfiguration
of your kernel see
.Ar /usr/src/sys/i386/doc/config_options.doc.
.Sh AUTHOR
Christopher G. Demetriou
.Sh BUGS
It is strongly recommended that you do *not*
change the bidirectional status of a port while there are programs
using the port.  Read that as: if you do, and it breaks, don't yell
at me; that's a really weird thing to do.
.Sh HISTORY
Originally part of cgd's com package patches, version 0.2.1, to 386BSD 0.1.