One of the most handy tools to have in IT support is a portable OS. Whether you want to perform a memtest, repair a faulty bootloader, scan for a virus or rootkit, or extract some mistakenly-deleted files from another drive, having a bootable USB drive around makes doing such things quick and easy. So in keeping with that idea, I present to you a step-by-step guide of how to install Linux Mint on a USB drive.

This also works for Ubuntu, Xubuntu, Lubuntu, Ubuntu GNOME, etc.

• First of all you’ll need two USB Sticks – your intended boot stick should be at least 8GB in size; the intended installation stick will be fine with 2GB.  I highly recommend using a USB 3.0 drive for your boot stick, to take advantage of the extra speed.
• Download your Linux distro. I’ve gone with Mint 15 (because it’s pretty), and chosen 32 bit for compatibility with other PCs.
• Insert your intended installation stick and put your chosen Linux on to it:
  • In Linux, use something like:  sudo dd if=~/Downloads/linuxmint-15-cinnamon-dvd-32bit.iso of=/dev/sdx
  • Under Windows, use UNetbootin to image your installer to the USB stick.
• Once your installation stick is ready, plug in your boot stick.
• Boot your computer onto the installation stick, and select “Install Linux Mint”.
• Follow your nose until you reach the Installation Type screen.  At this point, choose ‘Something else’ and click continue:

Warning:  be VERY certain of your target. Linux identifies different devices by letter (sda, sdb, sdc) and different partitions by number (sda1, sdd1, sdc2).  As you can see below, mine is /dev/sdb.

• Wipe the partition table on your boot stick if required; it should appear as a device containing only free space:

• Select ‘Free Space’ on your boot stick, and add a partition with the following characteristics:
  • Size: 512mb or over
  • Type: Primary
  • Location: I chose beginning; this is up to you
  • Use as:  Up to you; I went with Ext4
  • Mount point: /boot

• Once your boot partition has been created, it’s time to create your encrypted file system.  Select ‘Free Space’ on the boot stick again, and create a new partition like so:

• After I took the above screenshot, I decided I wanted an unencrypted space on the drive to allow me to share the drive between Linux and Windows.  To achieve this, I actually only used 20GB for this partition.  This allowed me to add a FAT32 partition later.  You can do this too, if you want.
• Clicking OK will create the new encrypted partition, mount it, and then create an Ext4 partition inside it as /dev/mapper/sdx_crypt. Select this new partition for your installation:

• Make sure that you select the correct device for the boot loader installation!  You want to choose your boot stick.  Do NOT choose /dev/mapper, use /dev/sdx instead.

• Edit your /dev/mapper/sdx_crypt partition and set a mount point of /.

• Click “Install now”. The installer will alert you that you haven’t provided any swap space.  This is fine – click continue.
• Follow your nose through the rest of the installation.

Once the installation is completed, you may want to set up a a swap file if you’re planning to boot on a system with low memory.