How to update the firmware for a K3 Kindle keyboard from Linux?

Question

From Linux, how do I update a K3 Kindle from 3.4 to 3.4.2 version?

This is a slightly different question than previous because it's Linux specific.

My device is:

Kindle Keyboard 3G (Free 3G + Wi-Fi)

Your serial number starts with "B006"

If you have software version 3.4.1, download Software Update 3.4.2.
If you have software version 3.4, download Software Update 3.4.2.

I'm just not sure exactly how to proceed once it's downloaded:

Amazon Device Support › Fire & Kindle Software Updates › Kindle Keyboard Software Updates› Transfer & Install Software Updates Manually

Software updates automatically download and install on your Kindle Keyboard when connected wirelessly; however, you can also manually download the software and update your device via USB cable.

Before you perform these steps, make sure you determine your software version. Go to Determine Your Software Version.

From your computer, go to Kindle Keyboard Software Updates and download the applicable software update file.
Transfer the software update file to your Kindle device:
    Turn your Kindle Keyboard on and connect it to your computer using the USB cable.
    Drag and drop the new update file from your computer onto the Kindle drive.

Note: Do not drop the file into one of the folders within the Kindle drive.
Monitor file transfer and disconnect:
    After the file has transferred successfully, eject the Kindle to safely disconnect your Kindle from your computer.
    Disconnect the USB cable from your Kindle and your computer.
Start the software update:
    From Home, press the Menu button, and then select Settings.
    Press the Menu button, and then select Update Your Kindle. This option will be grayed out if the most recent update has already

been installed or if the file transfer was not successful. Select OK to perform the update. Your Kindle will restart twice during the update. After the first update, you will see Your Kindle is Updating.

Obviously, the Kindle needs to be running to transfer files to it. But it also needs to have the screen locked. Yes? Then, just put the file in the root directory which is available?

Answer 1

the K3 automounted fine:

thufir@dur:/media/thufir/Kindle$ 
thufir@dur:/media/thufir/Kindle$ ls -al
total 44
drwxr-xr-x  6 thufir thufir 8192 Dec 31  1969 .
drwxr-x---+ 4 root   root   4096 Dec 28 10:41 ..
drwxr-xr-x  2 thufir thufir 8192 Nov 24 17:51 audible
drwxr-xr-x  2 thufir thufir 8192 Nov 24 17:51 documents
drwxr-xr-x  2 thufir thufir 8192 Nov 24 17:51 music
drwxr-xr-x  4 thufir thufir 8192 Dec 28 10:37 system
thufir@dur:/media/thufir/Kindle$ 
thufir@dur:/media/thufir/Kindle$ cp /home/thufir/Downloads/Update_kindle_3.4_3.4.2_B006.bin .
thufir@dur:/media/thufir/Kindle$ 
thufir@dur:/media/thufir/Kindle$ cd
thufir@dur:~$ 

Then I unmounted the K3. But, there's no update option. Registration shows:

Registration
Wi-Fi
Voice Guide
Device Password
Device Info

then menu, select settings, then menu again for the update option.