COMCONTROL(8)           FreeBSD System Manager's Manual          COMCONTROL(8)

NAME

     comcontrol - control a special tty device

DEPRECATION NOTICE

     The comcontrol utility is deprecated and will be removed in FreeBSD 16.0.

SYNOPSIS

     comcontrol special_device [drainwait number]

DESCRIPTION

     The comcontrol utility is used to examine and modify some of the special
     characteristics of the specified tty device.  If no arguments other than
     the device (or "-" for stdin) are specified, it prints the settings of
     all controllable characteristics.  This usage requires only read access
     on the device.  Only the superuser can change the settings.

     The following options are available:

     drainwait number
             Set the time to wait for output drain to the given number.  The
             units are seconds.  The default is 5 minutes, 0 means waiting
             forever.  This option is needed mainly to specify an upper limit
             of minutes to prevent modem hanging.

     The standard way to use comcontrol is to put invocations of it in the
     /etc/rc.d/serial startup script.

FILES

     /dev/ttyd?  dialin devices, hardwired terminals
     /dev/cuau?  dialout devices

SEE ALSO

     stty(1)

HISTORY

     Originally part of cgd's com package patches, version 0.2.1, to
     386BSD-0.1.  Once controlled bidirectional capabilities.  Little is left
     to control now that these capabilities are standard.

AUTHORS

     Christopher G. Demetriou

FreeBSD 15.1-STABLE-HBSD        August 31, 2025                  COMCONTROL(8)