Something like unionfs&#x2F;overlayfs, which are the magic allowing Linux Live CDs to &quot;modify&quot; files and directories stored on read-only medium.<p><a href="https:&#x2F;&#x2F;www.kernel.org&#x2F;doc&#x2F;Documentation&#x2F;filesystems&#x2F;overlayfs.txt" rel="nofollow">https:&#x2F;&#x2F;www.kernel.org&#x2F;doc&#x2F;Documentation&#x2F;filesystems&#x2F;overlay...</a>