The fine method, with GNU/Linux

Anyone can use this method since year 2019, when Freeduc flash sticks first were forged with live-build. One just needs to download and copy partitions containing the system's core; they are five times smaller to copy bitwise to the USB stick: one burns 3 GB instead of burning 16 GB.

One downloads the system's image in ISO-hybrid format. No need to uncompress it.

Date	ISO file	Checksum	Signature	Sources tarball
11/2022 target = x64 (64 bits)	4635574272			14035507200
01/2021 target = x64 (64 bits)	3319456			9888690
11/2020 target = i686 (32 bits)	3299872			9840380
09/2019 target = x64 (64 bits)	3123232			9313660
08/2019 target = x64 (64 bits)	3025120			8521660
06/2019 First version generated by live-build, target = x64 (64 bits)	3031040

Then you must copy the image bitwise, not as a plain file, to the USB stick. This works correctly only when the size of the USB stick is 16 GB. For a 8 GB stick, the persistence filesystem will be inconsistent, one would have to fix it, and for bigger USB sticks, there would be unused memory space.

With GNU/Linux, and line commands

First, one has to know which drive fits the plugged USB stick. One can type this command line: dmesg, scrolling messages should contain a few lines near the end, talking about the recently plugged USB stick, something like: ... scsi25 : usb-storage ... sdb: sdb1 ...
In that example, the right device is /dev/sdb.
Then, one has to copy the data with the command bar or the command dd :

1. With the command bar: install the package « bar » available with Debian and Ubuntu, it features a progress bar to monitor the copy.
   The command is: bar -if live-image-i386.hybrid.iso -of /dev/sdX
   please notice that X is a character, often b, c, d, etc. In that example, the right command would be: bar -if live-image-i386.hybrid.iso -of /dev/sdb
   N.B. : one would probably need super-user permissions to launch this command.
2. With the command dd : dd is available by default, no need to install it.
   Use it as: dd if=live-image-i386.hybrid.iso of=/dev/sdX status=progress bs=4M oflag=dsync
   .. Read the explanation above once again, do not confuse devices!

Create the persistence partition

In command-line mode, still with super-user permissions, one has to use a partition management tool to create the persistence partition, to use the space which remains at the end of the device.

Keeping on with the example, the stick is still managed by /dev/sdb, type the command fdisk /dev/sdb; that stats the interactive program fdisk. When it is running, one can see the internals of the systems born by the USB stick: type p (Print) : fdisk will show the existing partitions, numbered 1 and 2.

While fdisk is in use, type n (New), and p (Primary partition), and 3, finally validate a few times with the Enterkey. This creates a third partition using all of the remaining space. Type p (Print), the new structure can be checked: three partitions, numbered 1, 2 and 3. If everything is correct, type w (Write): this overwrites the previous version of the partition table. One can cancel the operations if any doubt, by typing q (Quit); it stops fdisk without modifying the partition table.

Format the partition table

On should have the shell's prompt (fdisk must be finished), then one can launch the command mkfs -t ext4 -L persistence /dev/sdb3. Please notice that if the USB stick is not driven by /dev/sdb, the file /dev/sdb3 does not match its third partition; then the syntax must be adapted.

Configuration of the persistence system

A configuration file must be put in the recently created partition. One can use a graphic tool to manage files; it should detect a partition named persistence, if there is none, one could try to unplug the stick and plug it again a few seconds later. The file manager allows one to see the partition, but if it is not launched with root permission, it is unable to touch directly files in that partition. However, it can tell the precise directory where the partition is mounted. Typically, something like /media/foo/persistence (foo is not the real name, it is more probably the user name instead).

Create a plain text file somewhere, with the file name persistence.conf, with a single line in it : / union; carefully check the file name, and the space between the character / and the word union. Finally, as a super-user, copy the file to the right place: cp persistence.conf /media/foo/persistence (of course, the user is not named foo, use the real name).

Et voilà.

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