I want to install Ubuntu to a 4Gb USB stick, so that I can boot it on other computers, but I heard that a persistent file system never deletes data and so just fills up. This would be a problem as I like to keep Ubuntu up to date, and downloading 100Mb worth of upgrades on a regular basis would fill up the drive quite fast if they never truly overwrote old ones.
So can someone please tell me if this is true and, also, if there are any advantages to using a persistent file system over just installing Ubuntu to the drive.
In addition, would it be possible to install the Ubuntu installer onto a normal installation of Ubuntu - ie, if I used the installer to install to the live stick, would I be able to get the installer back on the USB stick to install it on further machines? It's not really an issue if I can't, but I am curious. Thank you.