OK, I have successfully made a bootable Debian 9.4 Live USB (LXDE desktop) with persistence. The link I gave earlier (here it is again
) is fairly accurate, but I had to adapt a little, so you might too. This is the same as @arochester
's first link above also. Here are some notes to watch for if you decide to try it:
1. In Step 3, it describes shrinking the flash drive to create the persistence partition. I mention this first because I used Gparted in Linux to resize the USB stick, and even though it was successful... the flash drive would no longer boot up on Debian at all. So I went back into Windows and used LiLi again to install the Debian .iso on the USB drive. It may be best to prepare both partitions you will need on the USB stick before you begin. The first partition needs to be FAT32 (2 GB is enough, I used 4 GB), and the 2nd partition needs to be ext4 (I made it 8 GB, but probably won't need that much). Windows won't make an ext4 filesystem, so it's easier to use Linux for this. It is important that you label the ext4 partition as "persistence" (without quotes) or it won't work.
2. With the USB stick better prepared to begin, the other steps should mostly be okay. Just to clarify a couple more points...
In Step 4:
sudo chown user /media/user/persistence
# Don't use sudo if you open System Tools > Root Terminal.
# You may want to use the mount command to confirm that /media/user/persistence is already mounted.
In Step 5:
echo / union > persistence.conf
# Be sure there is a space between / and union. It doesn't work if you don't.
After I stumbled through and got everything right, persistence worked fine. I changed the panel appearance, added a text file to the desktop, and installed a satellite tracking programs... everything came back after a reboot. I did have to select the deb-src repository in Synaptic Package Manager to install the new program
One last note about persistence: It will NOT
do some things. You cannot upgrade the Debian system (kernel and other core components). You cannot install drivers. Although you can install/update some software... there are probably others that you cannot. It is a very handy feature, but it has limitations that may make it unsuitable for some uses.