I want to try ubuntu for first time , I am a total noob and not used any Linux distros before what I want to ask is I want to create a bootable live usb with ubuntu but i am creating it on a usb 2.0 so will it be very slow, I also want to add persistence to it and also can it delete or affect any data on my main hardrive when using ubuntu on my persistent live usb as i am a noob and don't want to destroy my windows and other files.
Ubuntu – Ubuntu on a live usb
bootlive-usbusb
Related Solutions
Persistence is saved in a file or partition named casper-rw, a persistent home file or partition named home-rw is also possible. A persistent install will save data, program installs, customized desktops, just about everything except some drivers which are loaded before the persistence file is read during boot, (NVidia graphics).
In a syslinux type install, (SDC, Unetbootin, Universal, Rufus, etc), the system resides in the root of the drive as does the casper-rw file. The filesystem for this partition is FAT32 thus maximum size for the persistence file is 4GB.
Prior to 14.04 syslinux type installs could also use a persistent casper-rw and home-rw partition. Persistent partitions no longer work except with grub2 type installs, (mkusb and the original MultiBootUSB).
Mkusb is easy to use, safe, versatile and will make a persistent partition of whatever size you want, it will then use remaining disk space to make a NTFS partition that is visible to both Linux and Windows.
Limitations, well you don't want to unplug a persistent pendrive while data is being written to persistence, luckily mkusb comes with persistence backup tools.
New user with encrypted home in a persistent live drive
Yes it is possible to create a new user with encrypted home in a persistent live drive made with mkusb. I have done it so I know that it works. It is probably easiest if you install gnome-system-tools and use users-admin.
sudo apt install gnome-system-tools
users-admin
or start it via the graphical user interface.
Select Add to create a new user and select encrypt home folder. Otherwise the password is not really meaningful in this kind of system.
Warning: it is very important to backup the system regularly and to remember the password to the encrypted system. Otherwise you might lose your data. There is no back door.
If you keep the default user, the system will auto-login (unless you change that setting). Log out and select the new user ('tester' in the example below) and enter the password.
If you intend to remove the default user, you should make your new user an administrator, and be sure that you can run sudo. (You should not be able to remove the default user without sudo in standard Ubuntu, and if you manage to remove it anyway, your system would be crippled with no user to manage the system.)
sudo deluser ubuntu # in standard Ubuntu (modify user name in the flavours)
Problems with Firefox and Thunderbird
It was more difficult to create a basic working Lubuntu system with a new user with encrypted home. And after further testing we found that neither Firefox nor Thunderbird works, not for the OP in Xubuntu and not for me in Lubuntu and standard Ubuntu. So I am affected too. I suspect that it is some security feature that stops the Mozilla software from working.
I installed Midori, a light-weight web browser, and it works without problems. It can be used for webmail (I tested with my gmail account). - But if it is necessary for you to use Firefox and Thunderbird, this kind of persistent live system is a dead end street.
Alternative: Installed system in a USB drive
An alternative is to make an installed system with or without encrypted disk or encrypted home if you wish - installed like into an internal drive, but into a USB drive. It is easiest to install it correctly, if you remove the internal drive from the computer, where you create it. There are some tips at the following links,
help.ubuntu.com/community/Installation/UEFI-and-BIOS
Ubuntu on a USB stick - mount options to reduce writes
Quick fix
This is a quick fix, that is not adding security against a qualified attack, but maybe it would be enough to prevent tampering by curious persons, to make your persistent live tweaks in Xubuntu 'noob-proof': move (rename) sudo and remove the gui tools to manage programs, gnome-software, update-manager and maybe software-properties-gtk.
sudo mv /usr/bin/sudo /usr/bin/opns
opns apt remove gnome-software
opns apt remove update-manager
opns apt remove software-properties-gtk
Or better, move sudo to some other name, that is more difficult to guess. The following screenshot illustrates that it works to use the 'moved sudo' command to install a program package,
opns apt install htop
Best Answer
I ran not only live USB but also complete installed Ubuntu from USB 2.0. It woks fine for most of the time.
making a live USB do not make any change to your present system. because you just write a ISO image on a USB using software like Unetbootin. During booting you have to select boot from USB option.
If you want a persistent system you have to install complete Ubuntu on a USB or Hard disk. Live USB do not save changes.
The installation of Ubuntu or any other OS only erase/ destroy data from your existing OS Hard Disk if you select to overwrite that disk. If you take care and install Ubuntu properly on another disk/ partition your existing OS shall be intact.
In some cases of dual Boot like Ubuntu and Windows some may face Boot problem. That can be repaired using Boot-Repair from Live USB.