attach a line discipline to a serial line
ldattach is used to attach a line discipline to a serial
line to allow for in-kernel processing of the received and/or sent data.
Depending on the line discipline being attached, one or more options may be
ldattach can be run from the command line
or at system startup by having init(8) read
ttys(5) entries to attach line
The following options are available:
- Use 2 stopbits instead of 1.
- Use 7 databits instead of 8.
- Do not daemonize.
- Use even parity.
- Turn on RTS/CTS flow control. By default, no flow control is done.
- Maintain modem control signals after closing the line. Specifically, this
- Use odd parity.
- Pass the data received from device to the master
device of a pty(4) pair and vice versa.
The name of the slave device is written to standard output.
- Specifies the speed of the connection. If not specified, the default of
9600 baud is used (4800 baud for
endrun(4) line disciplines only.
Chooses the condition which will cause the current system time to be
immediately copied to the terminal timestamp storage for subsequent use by
endrun(4). Only one can be used.
- Copy the timestamp when DCD is asserted.
- Copy the timestamp when DCD is deasserted.
- Copy the timestamp when CTS is asserted.
- Copy the timestamp when CTS is deasserted.
If no condition is specified, the
nmea(4) line discipline will timestamp
on receiving the leading ‘$’ character of each block of
- Specifies the name of the line discipline to be attached.
- Attach the endrun(4) line
- Attach the msts(4) line
- Attach the nmea(4) line
- Specifies the name of the serial line. device should
be a string of the form “cuaXX” or
cua(4) devices should be used
ldattach is started from the command line;
when started using init(8),
tty(4) devices should be used.
ldattach was not started by
init(8), the line discipline can be
detached by killing off the
init(8) to attach the
nmea(4) line discipline to
/dev/tty01 at 4800 baud using a device without a
carrier (DCD) line, add a line of the following form to
tty01 "/sbin/ldattach nmea" unknown on softcar
ldattach command first appeared in