picocom - minimal dumb-terminal emulation program
picocom [ options ] device
As its name suggests, picocom is a minimal dumb-terminal emulation
program. It is, in principle, very much like minicom(1) , only it’s
"pico" instead of "mini"! It was designed to serve as a simple, manual,
modem configuration, testing, and debugging tool. It has also served
(quite well) as a low-tech "terminal-window" to allow operator
intervention in PPP connection scripts (something like the ms-windows
"open terminal window before / after dialing" feature). It could also
prove useful in many other similar tasks.
When picocom starts it opens the terminal (serial device) given as its
non-option argument. Unless the --noinit option is given, it configures
the device to the settings specified by the option-arguments (or to
some default settings), and sets it to "raw" mode. If --noinit is
given, the initialization and configuration is skipped; the device is
just opened. Following this, picocom sets the standard-input and
standard-output to raw mode. Having done so, it goes in a loop where it
listens for input from stdin, or from the serial port. Input from the
serial port is copied to the standard output while input from the
standard input is copied to the serial port. picocom also scans its
input stream for a user-specified control character, called the "escape
character" (being by default "C-a"). If the escape character is seen,
then instead of sending it to the serial-device, the program enters
"command mode" and waits for the next character (which is called the
"function character"). Depending on the value of the function
character, picocom performs one of the operations described in the
"Commands" section below.
Commands are given to picocom by first keying the "espace character"
which by default is "C-a" (see "Options" below on how to change it),
and then keying one for the function (command) characters shown here.
Send the escape character to the serial port and return to
"transparent" mode. This means that if the escape character ("C-a",
by default) is typed twice, the program sends the escape character
to the serial port, and remains in transparent mode. This is a new
behavior implemented in v1.4. Previously picocom used to ignore the
escape-character when it was entered as a function character.
Exit the program: if the "--noreset" option was not given then the
serial port is reset to its original settings before exiting; if it
was given the serial port is not reset.
Quit the program *without* reseting the serial port, regardless of
the "--noreset" option.
Pulse the DTR line. Lower it for 1 sec, and then raise it again.
Toggle the DTR line. If DTR is up, then lower it. If it is down,
then raise it.
Generate a break sequence on the serial line. A break sequence is
usually generated by marking (driving to logical one) the serial Tx
line for an amount of time coresponding to several character
Baud up. Increase the baud-rate. The list of baud-rates stepped-
through by this command is: 300, 600, 1200, 2400, 4800, 9600, 19200,
38400, 57600, 115200.
Baud down. Decrease the baud-rate. The list of baud-rates stepped-
through by this command is the same as for the "baud-up" command.
Cycle through flow-control settings (RTS/CTS, XON/XOFF, none).
Cycle through parity settings (even, odd, none).
Cycle through databits-number settings (5, 6, 7, 8).
Show program options (like baud rate, data bits, etc). Only the
options that can be modified online (through commands) are shown,
not those that can only be set at the command-line.
Send (upload) a file (see "Sending and Receiving Files" below)
Receive (download) a file (see "Sending and Receiving Files" below)
After performing one of the above operations the program leaves the
command mode and enters transparent mode. Example: To increase the
baud-rate by two steps, you have to type:
C-a, C-u, C-a, C-u
assuming of-course that "C-a" is the escape character.
SENDING AND RECEIVING FILES
picocom can send and receive files over the serial port using external
programs that implement the respective protocols. In Linux typical
programs for this purpose are:
— rx(1) - receive using the X-MODEM protocol
— rb(1) - receive using the Y-MODEM protocol
— rz(1) - receive using the Z-MODEM protocol
— sx(1) - send using the X-MODEM protocol
— sb(1) - send using the Y-MODEM protocol
— sz(1) - send using the Z-MODEM protocol
— ascii-xfr(1) - receive or transmit ASCII files
The name of, and the command-line options to, the program to be used
for transmitting files are given by the "--send-cmd" option. Similarly
the program to receive files, and its argumets, are given by the
"--receive-cmd" option. For example, in order to start a picocom
session that uses "sz" to transmit files, and "rz" to receive, you have
to say something like this:
picocom --send-cmd "sz -vv" --receive-cmd "rz -vv"
During the picocom session, if you key the "send" or "receive" commands
(e.g. by pressing C-a, C-s, or C-a, C-r) you will be prompted for a
filename. At this prompt you can enter one or more file-names, and any
additional arguments to the transmission or reception program. After
that, picocom will start the the external program as specified by the
"--send-cmd", or "--receive-cmd" option, and with any filenames and
additional arguments you may have supplied. The standard input and
output of the external program will be connected to the serial port.
The standard error of the external program will be connected to the
terminal which---while the program is running---will revert to
canonical mode. Pressing ’C-c’ while the external program is running
will prematurely terminate it, and return control to picocom
picocom accepts the following command-line options
--baud | -b
Defines the baud-rate to set the serial-port (terminal) to.
--flow | -f
Defines the flow-control mode to set the serial-port to. Must be one
— ´x’ for xon/xoff (software) mode
— ´h’ for hardware flow control (RTS/CTS)
— ´n’ for no flow control
--parity | -p
Defines the parity mode to set the serial-port to. Must be one of:
— ´o’ for odd parity mode.
— ´e’ for even parity mode.
— ´n’ for no parity, mode.
--databits | -d
Defines the number of data bits in every character. Must be one of:
5, 6, 7, 8
--esacpe | -e
Defines the character that will make picocom enter command-mode (see
description above). If ’x’ is given, then C-x will make picocom
enter command mode.
--noinit | -i
If given, picocom will not initialize, reset, or otherwise meddle
with the serial port at start-up. It will just open it. This is
useful, for example, for connecting picocom to already-connected
modems, or already configured ports without terminating the
connection, or altering the settings. If required serial port
parameters can then be adjusted at run-time by commands.
--noreset | -r
If given, picocom will not *reset* the serial port when exiting. It
will just close the filedes and do nothing more. This is useful, for
example, for leaving modems connected when exiting picocom picocom
using the "Quit" command (instead of "Exit"), which never resets the
serial port. If "--noreset" is given then "Quit" and "Exit" behave
essentially the same.
--nolock | -l
If given, picocom will *not* attempt to lock the serial port before
opening it. Normally picocom attempts to get a UUCP-style lock-file
(e.g. "/var/lock/LCK..ttyS0") before opening the port. Failing to do
so, results in the program exiting after emitting an error-message.
It is possible that your picocom binary is compiled without this
--send-cmd | -s
Specifies the external program (and any arguments to it) that will
be used for transmitting files.
Default: "sz -vv"
--receive-cmd | -v
Specifies the external program (and any arguments to it) that will
be used for receiving files.
(Default: "rz -vv")
--help | -h
Print a short help message describing the command-line options.
picocom was written by Nick Patavalis (email@example.com)
The latest version of "picocom" can be downloaded from: