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Man Pages

Manual Reference Pages  -  JERM (1)


jerm - communication terminal through serial and TCP/IP interfaces


     Common options
     Device options
     Client options
     Other options
     Escape Characters
See Also


jerm [common_options] [device_options] [client_options] device_file jerm [-46] [-P port] [common_options] [client_options] host_name jerm -i [-46] [-P port] [common_options] [device_options] [client_options] host_name < device_file > device_file jerm -D [-46T] [-P port] [common_options] device_file


jerm is primarily intended to communicate with a remote machine through a serial interface. Additionally jerm can communicate with another through a TCP/IP connection like telnet(1) and relay a serial communication to a TCP/IP connection to another remote machine.

To connect a remote machine through a serial interface, use the first form. device_file should be a special device file of a serial interface (typically /dev/cu* ). The second form lets jerm connect to the remote machine host_name through the TCP port. In the case of invoking jerm with the third or the fourth form, it relays the communications between a serial and a TCP/IP ports. The former relays the specific machine host_name and the serial device_file, while the latter lets jerm work as a daemon; it listens to the TCP port first. After a connection on the port is established, then jerm opens the device device_file and relay the communications between the TCP port and the device. See EXAMPLES for more information.

The following options are available:

    Common options

-z Empty the log file at first.
-l log_file
  Write output characters to log_file. Since jerm always appends characters to log_file, use -z in conjunction with this flag to log a single session.

    Device options

-b speed
  Designate the speed of serial interface. The default is 9600.
-p n[one|e[ven|o[dd]]]
  Designate the parity of serial interface. The valid value is one of none’, even’ or odd’. The first character is suffice. The default is none’.
-d 7|8 Designate the bit length of data. The default is 8’.
-s 1|1.5|2
  Designate the stop bit. The default is 1’.
-f n[one|x|h[ard]]
  Designate the flow control. The default is none’.

    Client options

-x Starts in hexadecimal dump mode.
-r rnRN
  Set CR NL mapping method. Option argument rnRN consists of four charactears. Each character may be the one of the followings:

    ‘x’ Map to nothing. (drop)

    ‘r’ Map to CR.

    ‘n’ Map to NL.

    ‘t’ Map to CR+NL.

The argument r specifies how to map a CR from remote to local, n specifies how to map a NL from remote to local, R specifies how to map a CR from local to remote, and N specifies how to map a NL from local to remote. The default is rnrn’.

    Other options

-i Pipe mode. Initialize the standard input/output as a serial interface.
-4 Use IPv4 for TCP/IP connection.
-6 Use IPv6 for TCP/IP connection.
-P port
  Designate TCP port for TCP/IP connection. The default port is 8086’.
-T Use hosts_access(3) when accepting connection.

    Escape Characters

Typed characters are normally transmitted directly to the remote machine (which does the echoing as well). A tilde preceded by a Control-M or Enter (‘^M ~’) is an escape signal; the following are recognized:
^M ~ .
  Drop the connection and exit (you may still be logged in on the remote machine). When jerm is invoked as a relaying server (with-D) , Control-C (‘^C’) will terminate jerm. If in the pipe mode ( -i is specified ), jerm does not terminate. Send a hang up signal (typically kill -HUP) instead.
^M ~ ~
  Send a tilde (‘~’) to the remote machine.
^M ~ #
  Send a BREAK signal to the remote machine.
^M ~ > file
  Send the local file file to the remote machine as its input.
^M ~ x
  Toggle back and forth between the normal and the hexadecimal dump mode. The hexadecimal dump mode displays received characters in hexadecimal.
^M ~ r rnRN
  Set CR NL mapping method in the same manner as the -r option.
^M ~ ?
  Get a summary of the ^M ~’ escapes.


The command:

    jerm /dev/cuaa0(Fx)

    jerm /dev/dty00(Nx)

    jerm /dev/cua00(Ox)

    jerm /dev/cu.usbmodemUSB-COM(Darwin/Mac OS X)

connects a remote host through a serial interface. The actual device file may vary.

.Fx HOST1 connects to the remote machine RMACH through a serial interface, The command:

    jerm -D -P 9800 -b 4800 /dev/cuaa0

on HOST1 will relay RMACH to TCP port 9800. Then the command:

    jerm -P 9800 HOST1

.Nx HOST2 can communicate with RMACH. Instead of the above command, execute the command:

    jerm -i -P 9800 HOST1 -b 4800 < /dev/dty00 > /dev/dty00

on the HOST2 and connect HOST2’s serial interface with Darwin HOST3, then the command:

    jerm /dev/cu.usbmodemUSB-COM

on HOST3 connects RMACH through HOST1 and HOST2.


cu(1), tip(1), telnet(1)


.An KANDA Toshihiro


Although jerm with TCP/IP connection is analogous to telnet(1), jerm does not support telnet protocol.
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