i wish to learn unix from scratch including shell scripting.I am basically an electronics engineer so no idea about it.can anybody suggest me some online good tutorial of unix or embedded linux.plz guide me in this endevour....
The place to start is tldp.org, the Linux Documentation Project. There are hundreds of HOWTO's on different topics, and more in-depth guides, like
"Introduction to Linux: A hands-on guide", and "BASH guide for beginners"(shell scripting), and dozens more.
If you really want to learn how linux works, I would avoid distro's like Ubuntu like the plague. They are great if you just want to point and click, but really don't teach you anything about how linux works.
What I would reccommend is having a couple of machines, one with an easily installed distro(I prefer OpenSuse and Fedora to Ubuntu),and an older one to play with.
If you want to get down and dirty, but need some step by step instructions, you should definitely look at LFS(www.linuxfromscratch.org). Great for an older second computer that you dont mind setting aside for a few days. LFS includes very detailed step by step instructions on how to build your own linux box piece by piece, learning about the kernel, the init process, the directory tree and where everything is(all stuff that is very important, but almost completely hidden by the main distros).
Once you complete the process, you will feel like your brain has expanded about 50%, and then you can move on to a pre-built distribution. It will require quite a bit of work, but the instructions are excellent, and don't just tell you what to do, but why.
Before you do this, at least read some of the beginner guides on TLDP, just so you can understand the basics of commands, etc. I wouldn't recommend LFS for just anyone, but if you're an EE and want to learn about more than icons and pretty graphical package managers, LFS may just be for you.