Reddit reviews A Practical Guide to Linux(R) Commands, Editors, and Shell Programming

>I do have a textbook called "C: A modern approach" by King, but like I said before, I think it focuses more on the coding aspect.

Most books that focus on C are going to be about learning the language. If you want to learn low level stuff, you need to find books that focus on them (and they'll usually incidentally use C). The language itself is quite small and minimalistic in what it can do. Most heavy handed things like networking and GUIs require interaction with the OS.

Eg, if you wanted to do networking, you could use the Windows API or the POSIX socket API (POSIX being the standards that *nix systems follow -- and certain versions of Windows). Or you could use a higher level library like curl for cross platform support (and a wealth of nicer features).

>Can somebody please guide me on where to start?

Firstly, as much of a linux fanboy I am, I do want to make sure you know that you don't need to use Linux for any of the other things you wanted to learn (low-level programming, command lines, networking, etc). In fact, my OS class mostly used Linux, but we started out with a project using Windows threads (I guess the prof wanted us to see the difference from POSIX threading).

All that said, I do think Linux is something you'd want to learn and that a lot of low level things just seem more natural in Linux. But I'm biased. Linux fanboy, remember?

I'd start with downloading a Linux OS. Doesn't really matter which. I'd recommend going with Ubuntu. It's the most popular, easiest to find help with, and seems to be what most web servers are running, to boot. You can play around with the GUI for a bit if you want. It won't feel that different. Modern OSes sort of converged into the same high level ideas.

My favourite book for getting into the command line ever so slightly touching the low level aspects of OSes is Mark Sobel's A Practical Guide to Linux Commands, Editors, and Shell Programming. It will include some basic knowledge of Linux, but mostly focuses on the command line. But this is very useful because not only is the command line very practical to learn, but you'll end up learning a lot about Linux in the process (eg, by learning how everything is a file, how pipes work, etc). And arguably the command line a super big part of Linux, anyway. It makes sense as the first step.

Now, for the next step, you need to know C very well. So finish with your class, first. Read ahead if you have to. Yes, you already know if statements and functions and all, but do you understand pointers well? How about function pointers and void pointers? Do you understand how C's arrays work and the usage of pointer arithmetic? How about how arguments are passed to functions and when you'd want to pass a pointer to a function instead? As a rough skill testing question, you should implement a linked list for arbitrary data types with functions such as prepending, appending, concatenating lists, searching, removing, and iterating through the list. Make sure that your list can be allocated and freed correctly (no memory leaks).

Anyway, the next step is to learn OSes. Now, I said OSes and not Linux, because the Linux OS is a bit constrained if you want to learn low level programming (which would include a knowledge of what OSes in general do, and alternatives to OSes like Linux). But never fear, pretty much any OS book will heavily use Linux as an example of how things work and consequently explain a great deal of Linux internals. I can't recommend a class because mine was a regular university class, but Tanenbaum's Modern Operating Systems is a good book on the subject.

In particular, you can expect an OS class to not merely be focused on building an OS yourself (my class worked on aspects of OS101 to implement portions of our own OS), but also on utilizing low level aspects of existing OSes. Eg, as mentioned, my class involved working with Linux threading, as well as processes. We later implemented the syscalls for fork, join, etc ourselves, which was a fascinating exercise. Nothing gets you to understand how Linux creates processes like doing it yourself.

Do note, however, that I had taken a class on computer architecture (I found Computer Organization and Design a good book there, although note that I never did any of the excerises in the book, which seem to be heavily criticized in the reviews). It certainly helps in understand OSes. It's basically as low as you can go with programming (and a bit lower, entering the domain of computer engineering). I cannot say for sure if it's absolutely necessary. I would recommend it first, but it's probably skippable if you're not interested (personally, I found it phenomenally interesting).

For learning networking, Beej's book is well written. You don't need to know OSes before this or anything.

Sure thing! I completely understand the frustration. Setting up config files seems antiquated...but there are a few very nice things about them.

1. You can reconfigure the files from any computer with ssh or putty available, and don't have to configure VNC or another screen sharing program to do it
   
   
2. Configuration files are simply text files, so if you need to do a reinstall you can simply back up the necessary files, reload the OS, and reload the configuration files. The more convoluted your setup, the more files you'll need to back up, but at least you know when you reload them your configuration is saved. While this is true of the %appdata% folder on Windows as well, it's still a nice perk I feel.
   
   The more time you spend with Linux, the more familiar the language will become. Remember that you didn't always speak English (or whatever your native tongue is), but now you can typically do it without thinking. Linux is very similar in that once you learn the words and flags you want to use, it will seem simple.
   
   If you're looking for a good book to get you started, I can't recommend this one enough: A Practical Guide to Linux: Commands, Editors, and Shell Programming. Here's my description of it from another l4n post:
   
   It's a great book for a beginner who doesn't want to get a Dummies book that is mostly concerned with the GUI and doing all the same things that you would on Windows or Mac OS, but instead wants to learn about what you can do without a GUI. It's a great reference book as well, containing the man pages for many commonly used and built-in commands. If you're not sure what the man(ual) pages are, they're one of your best resources for information about (most) any command on your system. "man man", in addition to being a great band, is a command that you can run to find out more about the man pages. For a good example that shouldn't overwhelm you, run the command "man cp" and see what all the options for the copy command are. A good way I've heard the man pages explained is that it will not tell you how to use a command, but it tells you the things a command can do. How you use it is up to you!
   
   Also, I (shamefully) have not done this completely, but if you want to learn about how the core of most any Linux system works, install Arch using their fabulously laid out Beginners Guide

I disagree.. you should definitely learn red hat/fedora/centos in terms of network configuration files, other config files etc etc if you want to have a good knowledge of server level/enterprise level linux. Red-hat based distros are MUCH more widely used for server implementations than debian or slackware.. But that said definitely learn the debian way too. Linux in a Nutshell is a good back, or this book is also quite good: http://www.amazon.com/Practical-Guide-Commands-Editors-Programming/dp/0131478230/ref=sr_1_16?ie=UTF8&s=books&qid=1250956616&sr=8-16 -- Another good one is the Linux Quick-Fix Notebook- excellent excellent book