This is tested with linux Mint XFCE 21.3 Virginia
Situation: You want to point Virtualbox or VMWare or whatever to the Live CD ISO and setup a small virtual hard drive (or even USB key) to act as persistence.
There’s a load of stupid complicated guides out there when the process is actually stupidly simple as many of these things are, if a little sneaky.
Step 1: Download the Distribution’s Standard Live CD
Yes, just the normal live CD
https://www.linuxmint.com/download.php
Step 2: Create Your Virtual Machine (If You’re Going To Use One)
So just create your virtualbox virtual machine, or build your target computer or whatever it is you’re going to run this on.
NB: In virtualbox be sure to tick the “Live CD/DVD” checkbox when you set the CD image (in Settings > Storage), this prevents it from being “ejected”.
For your persistent drive, just make a virtual disk or use a physical USB drive, or internal hard drive, or whatever, if it’s something that you can create a filesystem on, you can use it.
Step 3: Create a Filesystem On Your Persistent Disk
Boot up the target computer/vm using the Live CD, Open the disks utility (or whatever partition editor you like), and do the needful to create an EXT4 partition on that persistent disk, you must call that partition, that is give it the label, “writable”
Step 4: Test It
Reboot with that livecd again, and this time hit TAB at the boot menu to edit
Look for the string “quiet splash” and replace that with “persistent”
Hit enter to boot
Note that you will not see the spolash screen, just lots of boot messages scrolling by, that’s fine, it will boot.
Create a folder on the desktop, reboot again being sure to do that same boot menu edit, and make sure it comes back.
Step 5: Make It Not Require Boot Menu Edit Each Time
Oh man, this is super kludgey, but hey it works, take your ISO image, make a copy, and now edit that copy in a hex editor (eg hexedit),
search for the string “quiet splash” and replace it with the string “persistent “ (with excactly 2 spaces on the end, to keep them the same length), it appears a few times times in the ISO, be sure to search through the entire ISO, some of the occurences are at the start, some are nearer the end.
Save it, attach it to your VM or burn it or whatever, and then boot that. Job. Done.