Everyone knows what a Linux shell is -- you open up a Linux terminal window (such as Konsole or xterm), type in some commands, and there you are, using your Linux shell. Write your commands to a file, make it executable, run it, and you're a shell programmer. But did you know that there are different shells that you can use, and that each shell operates in a slightly different way?

Shell is a program, which interprets user commands. The commands are either directly entered by the user or read from a file called the shell script.

A shell is a command interpreter which allows the user to interact with the computer. The way things work is simple: the user types in commands, the shell interprets them and performs the tasks it was asked to do, and finally it sends the result to the standard output (which is usually the screen). For example, the output of the ls command can be something like:

The Bash shell is the default shell environment in most Linux distributions, including all flavours of Debian. One default feature of the Bash shell is to record a history of all the commands entered by a user in a log file called .bash_history, found in the user's home directory.

The Bash Shell provides the ability to create symbolic names which the shell stores in memory and which can be assigned values so that it can be used repeatedly in a shell script.

Many times you might not be sure about which shell you are currently using. Especially if you are not on your system and logging into someone else’s, or maybe ssh’ing into a remote server. Worry not, because here are few simple commands that you can use to find out which shell you are using currently.

Scripts are files that contain shell commands which may be short or can be very complex. Scripts just make it easier because you can invoke one command to run all of the commands in the script. Here instead of using 8 separate commands you can use one command to execute all of them.

Nagios is the foundation for many networking applications world wide and is know for its flexibility. Building upon those concepts is a new project named the Nagios Visual Shell (V-Shell). What follows is a short review of V-Shell and an interview with the lead developer of this new Nagios project.

In this article we’d like to present the basic concepts needed to navigate the console world. We are going to find out what a shell is all about, what is a terminal, and what the famous console is actually for.