I run Ubuntu using a live boot from usb flash drive and but I am not able to save files or install any 3rd party software......Is there any way where I can save files on usb drive itself so that when I hook up the usb drive I am able to use all the work I did in the last session ..........
Mkusb will make a Live Persistent install to USB that will retain all of your changes without the need of doing a Full install, Mkusb will do either a MSDOS or GPT install.
It will work on a 4GB or smaller USB drive, a Full install of Ubuntu requires an 8GB drive minimum.
Mkusb creates an iso9660 partition for the OS, a casper-rw partition to install programs and save files and a FAT32 partition that both Linux and Windows can use for data.
One way is to use another installation medium to install Ubuntu to the flash drive as if it were a hard disk. This requires a rather large flash drive, however (32 GB would be recommended, though it would probably work in 16 GB if you don't need to install too much additional software). If you want to use a 16 GB size, you might prefer Lubuntu, which installs fewer and smaller packages.