statserial(1) display serial port modem status lines


statserial [-n | -d | -x] <device-name>


Statserial displays a table of the signals on a standard 9-pin or 25-pin serial port, and indicates the status of the handshaking lines. It can be useful for debugging problems with serial ports or modems.

The optional device-name parameter is the full name of the device file for the serial port in question. If not specified, the default is taken from the environment variable MODEM if set, otherwise /dev/cua1.


Each of the command line options is mutually exclusive.

Normally statserial will loop continuously, updating the status at one second intervals; you can exit using Control-C. The -n option disables looping.


With this option the status of the modem is printed as a decimal number. The bits are encoded as follows (XXX indicates unused bits):

| 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |

This option is the same as -d, except that the output is in hexadecimal.


Statserial only works with devices that support the TIOCMGET ioctl.

You need permission to read the device file.

The device file may be locked if other applications are using it.


Statserial was written by Jeff Tranter ([email protected]), later updated by Frank Baumgart ([email protected]) and is released under the conditions of the GNU General Public License. See the file COPYING and notes in the source code for details.