Important Concepts For Linux Beginners – Shells and Utilities
By Levi Reiss
A shell is the command interpreter program that serves as an interface between some users and 
the operating system itself. We say some users because most users rely on the graphical user interface. The Windows shell is the DOS command line interface accessed by clicking on Run and then entering the cmd command. The Windows graphical user interface is Explorer. This article describes the Damn Small Linux shell interface and several utilities, useful programs that may be launched from the shell. A subsequent article will describe the corresponding graphical user interface.
Why would anyone want to bother with a shell when the prettier, easier-to-learn and easier-to-use graphical interface is available? The answer is: It depends who you are and what you want to do. For system administrators or their associates it’s often much less cumbersome to use the shell rather than the graphical user interface. While Damn Small Linux commands may be quite arcane, they are often very powerful. And efficient. The Linux way of performing administrative and other technical tasks admittedly takes time to learn and master. But it does the job and does it well. In all fairness, many Windows systems administrators often apply command-line utilities. But they don’t have a powerful shell to help them do their work.
Historically Unix used the Bourne shell, the C shell which resembles the C programming language, and the Korn shell. Linux’s most widely used shell is Bash, also spelled BASH, the (Bourne-Again Shell). Damn Small Linux offers many shells but most people go with Bash both to communicate interactively with the operating system and to write programs known as shell scripts. If you program in Linux no matter which programming language you use you should learn some Bash specifics.
Utilities enable you to handle some very sophisticated processing. You can think of them as commands or as prewritten programs. Unix-Linux people often send the output of one command or utility to another command or utility for further processing. For example, the ps command displays active processes. It tends to generate voluminous output, especially in a busy system. Let’s say that you are interested only in the processes associated with a given terminal. You send (the technical term is pipe, expressed by the | character) the output of the ps command to the grep utility which looks for patterns within the input. You code a single line, multipart command to obtain the list of processes associated with that particular terminal. Unix and Linux are well known for elegant solutions. In contrast the Windows solution to this information need is much more clumsy.
The grep utility has many other uses including validating e-mail addresses. Let’s say that your web site asks potential subscribers to furnish their e-mail accounts when signing up for a newsletter. A sophisticated but relatively short statement coded in grep could validate e-mail accounts.
Other Damn Small Linux text processing utilities include the related egrep and fgrep commands, mawk a pattern scanning and text processing language, sed an editor that handles large files, and diff a utility that compares files. DSL provides utilities that compress and archive files, and a wide range of other utilities. If you need them, these Linux utilities can be very useful and time-saving.
Our next subject is Linux programming support.
Levi Reiss has authored or co-authored ten books on computers and the Internet. He loves the occasional glass of wine as exemplified by his wine websites including http://www.theworldwidewine.com. He teaches Linux and Windows operating systems plus other computer courses at an Ontario French-language community college. Visit his new website http://www.linux4windows.com which teaches you how to download and run Damn Small Linux on Windows computers, even if they are “obsolete.”
Linux terminals share alot in common with their primitive ancestors such as vt100 like consoles. These early devices is capable of sending sequences that signaled events outside of the normal flow of typed characters, such as escape, tab, linefeed…etc. Linux uses CTRL key to send out these out of band signals. This article summarises many of the commonly used control sequences that are used in all Linux terminals.
A few years earlier I had experimented with RedHat Linux but had no real success with it as it had problems detecting my usb keyboard and mouse. Which was obviously a bit of a non-starter for me. I knew that big advances were being made in the Linux world so I decided to do a bit of research.
I downloaded the ISO of Ubuntu Linux from the Ubuntu website 
Installing Linux on your wireless router has many benefits and in my opinion few risks. The one risk you do face is turning your router into a “Brick”. Now, this does seem like a big chance to take but there are many options if upgrade fails. Also, if you follow the installation instructions for each wrt54g firmware distribution you won’t have a problem.
According to Robert Morrow, a retired Air Force Academy electrical engineering professor, WiFi and cellular data are on the way out because the future belongs to WiMax. There are others, however, who are not quite as glowing in their praise of the emerging WiMax technology, and who believe that it will prove too expensive to have any real practical value.
signal within your area of operation. If you are using a Omni directional antenna that is causing half the signal to travel outside your building, you have a major security problem. Also while using your wireless directional antenna turndown transmit power to reduce your signal strength if you can.
