Using Kubos Linux


This document is intended as a general guide for creating, loading, and using Kubos projects and other files within the user space of Kubos Linux.

Communicating with an OBC

There are currently three primary methods for users to communicate directly with their OBCs:

  • Via a debug UART port
  • Via SLIP using a UART port
  • Via an ethernet port (not supported by all boards)

Debug Console

Each board will have some debug port available, which will then be connected to your computer via USB. See the appropriate Working with {board} document for more information.

If the target board is correctly connected to your host computer, you should see a /dev/ttyUSB* device in your Vagrant box. The VM is set up to automatically forward any FTDI cables that connect to a /dev/FTDI device for ease-of-use.

The Vagrant image comes pre-packaged with a minicom serial connection configuration file. You can connect with this configuration file using the command

$ minicom kubos

Alternatively, you can manually create a serial connection with minicom (or other terminal application) using the following connection configuration:

Setting Value
Baudrate 115200
Bits 8
Parity N
Stop Bits 1

Once connected, you can log in using either a user that you’ve created, or root, which has a default password of ‘Kubos123’.

Fully logged in, the console should look like this:

Welcome to Kubos Linux

Kubos login: root
Jan  1 00:00:16 login[212]: root login on 'ttyS0'
~ #


Please make sure to either logout of your board, or change it back to the root user’s home directory before beginning any file transfer


Using SLIP over a UART port allows users to communicate with a target OBC as though it has a normal network connection set up. This is most useful for communicating with OBCs which do not provide an ethernet port.

All supported boards include SLIP configuration in their /etc/network/interfaces file.

In order to communicate with an OBC from the Kubos SDK, users will need to do the following:

  • Connect an FTDI cable to the pins of the UART port (please refer to the UART section of the appropriate Working with {board} document for details about the default SLIP UART port for the board)

    • Ground -> Ground
    • TX -> RX
    • RX -> TX
    • RTS -> CTS (Might not be available on all boards/UART ports)
    • CTS -> RTS (Might not be available on all boards/UART ports)
    • Vcc -> ignore

    FTDI cables typically have the following pinout:

    Pin Color Function
    1 Black Ground
    2 Brown CTS
    3 Red Vcc
    4 Orange TX
    5 Yellow RX
    6 Green RTS
  • Connect the USB portion of the FTDI cable to the host machine

  • Issue ls /dev and identify the /dev/ttyUSB* device associated with the FTDI cable

  • Set up the SLIP device

    • If the UART port has RTS/CTS available, issue the following:

      $ sudo slattach -s 115200 -p cslip {USB-device} &
    • Otherwise, issue this command instead:

      $ sudo slattach -FL -s 115200 -p cslip {USB-device} &
  • Define a new network interface for the device:

    $ sudo ifconfig sl0 pointopoint up
  • Finally, ensure that the SLIP traffic will be routed to the SDK’s host IP:

    $ sudo route add dev lo

Worth noting, the baud rate, protocol, and IP addresses may all be changed. In this case, the corresponding values in the OBC’s /etc/network/interfaces file should also be changed to match.


Some OBCs support communication via an ethernet port. Once configured, this port can be used as an alternate method to access the board’s shell interface and to transfer files.


Connect an ethernet cable from the board to either your computer or an open network port.

Log into the board using the debug console and then edit /etc/network/interfaces. Update the IP address field to be an address of your choosing.

Once updated, run the following commands in order to make the board use the new address:

$ ifdown eth0; ifup eth0

The address can be verified by running the ipaddr command

Communicating via SSH

Once a board has been given a valid IP address (via ethernet or SLIP), you can create an SSH connection to it.

This can be done from either the SDK or your host machine.

To connect from the command line, run ssh kubos@{ip-address}. You will be prompted for the kubos account password.

You can also use a tool, like PuTTY, to create an SSH connection.

File Transfer

Once your board is connected and running you can begin transferring files to it. There are two supported methods of file transfer: scp and ZMODEM over minicom.


Transferring files using scp requires the board to have an IP connection using either ethernet or SLIP.

Once the IP address has been set, you can transfer files to and from the stack using the scp command. This command can be run from either the SDK or your host machine.

For example, if I wanted to send a file on my host machine, test.txt, to reside in the kubos account’s home directory, given a stack IP of, I would enter:

$ scp test.txt kubos@


While file transfer can be done over a SLIP connection, it is significantly faster and more reliable when done over an ethernet connection instead (for boards which have an ethernet port available)


If your board only has serial connections and there is no spare UART for SLIP, you can still transfer files over the debug serial console using minicom.

Connect to the board through minicom (the file transfer protocol is not guaranteed to work with any other terminal program)

$ minicom kubos

Login to the board

Welcome to minicom 2.7

Compiled on Feb  7 2016, 13:37:27.
Port /dev/FTDI, 21:26:43

Press CTRL-A Z for help on special keys

Welcome to Kubos Linux
(none) login: root
Jan  1 00:00:11 login[210]: root login on 'ttyS0'
~ #

Navigate to the location you’d like the received file to go.

~ # mkdir righthere
~ # cd righthere
~/righthere #

Issue the zModem command to prep the board to receive a file

$ rz -bZ

Press Ctrl+a, then press s to open the minicom file transfer dialog.

| zmodem    |
| ymodem    |
| xmodem    |
| kermit    |
| ascii     |

Select zmodem

+-------------------[Select one or more files for upload]-------------------+
|Directory: /home/vagrant                                                   |
| [..]                                                                      |
| [linux]                                                                   |
| [newprj]                                                                  |
| minicom.log                                                               |
|                                                                           |
|              ( Escape to exit, Space to tag )                             |

               [Goto]  [Prev]  [Show]   [Tag]  [Untag] [Okay]

Select the file to send:

Press g to open the Goto dialog and navigate to the desired folder (full pathname required).

Press enter to open the file selector dialog and specify the file you want within the current folder.

+-------------------[Select one or more files for upload]-------------------+
|Directory: /home/vagrant/linux/build/kubos-linux-isis-gcc/source           |
| [..]                                                                      |
| [CMakeFiles]                                                              |
| CMakeLists.txt                                                            |
| CTestTestfile.cmake                                                       |
| cmake_install.cmake                                                       |
| linux                                                                     |
|                                                                 |
|                +-----------------------------------------+                |
|                |No file selected - enter filename:       |                |
|                |> linux                                  |                |
|                +-----------------------------------------+                |
|                                                                           |
|              ( Escape to exit, Space to tag )                             |

               [Goto]  [Prev]  [Show]   [Tag]  [Untag] [Okay]

You should see a progress dialog as your file is transferred to the board.

+-----------[zmodem upload - Press CTRL-C to quit]------------+
|^XB00000000000000rz waiting to receive.Sending: linux        |
|Bytes Sent:  41984/  99084   BPS:8905     ETA 00:06          |
|                                                             |
|                                                             |
|                                                             |
|                                                             |
|                                                             |

Once file transfer is complete, you should be able to press enter and use your new file

+-----------[zmodem upload - Press CTRL-C to quit]------------+
|^XB00000000000000rz waiting to receive.Sending: linux        |
|Bytes Sent:  99084   BPS:7982                                |
|                                                             |
|Transfer complete                                            |
|                                                             |
| READY: press any key to continue...                         |
|                                                             |

Press Ctrl+a, then q to bring up the dialog to exit minicom. Hit enter to quit without reset.

Using Peripherals

Each board has a variety of different ports available for interacting with peripheral devices. Currently, users should interact with these devices using the standard Linux functions. A Kubos HAL will be added in the future.

Please refer to the appropriate Working with {board} document for more information about the specific peripheral availability.

User Accounts

In general, it is preferred to use a non-root user account to interact with a Linux system. A default user account ‘kubos’ is included with Kubos Linux. Other user accounts can be created using the standard Linux commands (adduser, useradd, etc).

All user accounts should have a home directory in the format ‘/home/{username}’.

The passwd command can be used to change the password of existing user accounts.

Kubos Linux File System

There are a few key directories residing within the Kubos Linux user space.


All user-created files should reside under the /home directory. This directory maps to a separate partition from the root file system. As a result, all files here will remain unchanged if the system goes through a kernel upgrade or downgrade.

The home directories of all user accounts, except root, should live under this directory.


Any files not residing under the /home directory will be destroyed during an upgrade/downgrade


All log files generated with rsyslog reside in this directory.


This directory is included in the system’s PATH, so applications placed here can be called directly from anywhere, without needing to know the full file path.


All user-application initialization scripts live under this directory. The naming format is ‘S{run-level}{application}’.

Resetting the Boot Environment


This is a case which normal users should never encounter, but becomes more likely when initially testing custom Kubos Linux builds. Due to the blocking nature of the behavior, this information has been included in this doc in order to make it more prominent.

If the system goes through the full recovery process and the bootcount is still exceeded, it will present the U-Boot CLI instead of attempting to boot into Kubos Linux again.

If this occurs, follow the instructions for resetting the boot environment.