I created a persistent usb installation from a 10.10 live cd using the "Boot Multiple ISO" utility and their "PDL Casper-RW" creator. I really like it, have made several changes to the install, and now find myself using it on the go more than I expected to. I would like to add a password and force login to the default user to add a little security. Is there anything unique or special about the Live-CD environment that would prevent this or make it difficult. If not what is the easiest way to do it so as not to miss something and break my stick?


As far as I know, the LiveCD environment is not meant to be changed so much. Yes you can add files, as in the persistent data storage portion. However, most of the programs and files are kept in a squashfs file system, which does not easily allow any change. I can't remember whether the configuration files and password files would be in the persistent storage or the squashfs system.

The LiveCD environment, although it is faster, doe snot easily allow changes of programs, or even update thereof. When you update a deb file, it is actually ADDED to the persistent storage portion of your disk.

With my experience of the USB-based Linux installations, I would rather have a full installation of Linux on a USB disk, from which I boot, just as if it was an external hard disk over USB. I then have a full access to all the files in an ext4 file system, for example, and I easily can replace any file I want, be it program, DEB module, data or config. It is a bit slower, but better if you plan on using it on a regular basis, not only to deo some boots here and there.

If you want to go ahead with a full installation, you just have to remember that the GRUB must be installed on the right device (/dev/sdb, for example, NOT SDA), and it should be the master boot record of the disk, not the partition. Also I found with experience that not all USB keys are created equal. Some are giving me more headache than others.

Make sure you have a good backup of all data files you have on your computer internal hard disk before proceeding. I overwrote the boot record of my hard disk once, and it was once too many. I learned the lesson.


Since Linux use swap file partition, you should manually partition the USB key you use, and have no swap partition. Because of its nature, a swap partition will cause too many read/writes on the USB key, which may shorten the lifetime of the key on this part of the storage area, eventually causing problems.

  • Good to know before I go too far. So let's say I have a laptop, I'll pop the internal disk out, start from a LiveCD, partition the whole usb to ext4 then do a regular install to it? Does that sound like a plan? – Dennis Jan 24 '11 at 14:14

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