Shell in Linux/Unix
Posted by Modestas J on 21 February 2012 11:03 AM
Shell is not a new word for most individuals who use Linux/UNIX operating system. A shell is a traditional interface that provides the user with a command line surface where he or she can type codes and run them. The work of the shell is to interpret commands that the user enters as text.
There are two types of Linux shells. They include C shell and Bourne shell. Bourne shell is the most common easy to use command line interpreter. Stephen Bourne is the engineer behind its source code. C shell is not conversant with many people. It developed long after the Stephen Bourne established his C shell. The programmer behind its source code is Bill Joy.
Both shells are very useful in scripting. They have languages are powerful and have many command line options that users can use interact with them. The command line shell accepts text and translates it as commands. The source code behind them is the one responsible for executing user commands. In Linux/UNIX operating system, the shell automatically loads on start up of the machine.
In all C shell or Bourne shell commands lines, the commands are the same. They are both available in different versions. The command options do not change very much. The only thing that changes is the internal structure with introduction of new commands options. The commands are stand alone executable units.
All shells come with an inbuilt command known as “man” that is used to display all available commands. In addition, the man command provides detailed information on how to use the commands options. The man command acts like a manual. Some of the things you can perform using the command line include
The command second-handed is “$ echo $shell”. Folks use this control to put on view or to verify the edition and kind of shell they are using. When executed it echoes in a table outline the kind and the edition of the shell.
2. Change default shell
You can make specially the command line and transform the default shell. This can be achieved with “$ which bash” command. It provides an interactive screen where you can put in your desired value.
3. Password altering
By evasion all the command line shell, come with a preset password. It is advisable you change the default password and input a new password that you can easily master. The command uses is “$ passwd”. When you run, it executes and provides you with a screen where you can enter the desired password. The password should be of reasonable length for security purposes. Command line shells do not display the characters of your password.
4. File catalog
You can catalog all the files that are currently in the index that you are using. The “ls” command responsible for the work. It puts into view all the files that are in that directory. If no files, the command executes but echoes out nothing. In addition, you can utilize the “ls” command alongside other flag options.