Lec. 4 Configuring the Shell

The Shell
The user interface of Linux is provided by a command language called the shell. There are several shells available differing in the facilities they provide. The most common ones are;
Bourne Shell Bash (Bourne Again Shell) C Shell T Shell Korn Shell
Of these BASH is by far the most popular one and is choosen to be the default shell to use on the Sheffield University HPC computers (iceberg) .
Format of Commands
For historical reasons, most important Linux commands are only two letters long. This brevity can sometimes make them difficult to remember, and it is not always easy to tell from a sequence of commands exactly what is happening. Also Linux distinguishes upper case letters from lower case, and insists that many commands are written in lower case. Typing a command in upper case will probably generate the response
Command not found
A typical Linux command consists of a general command word, which may be followed by optional parameters that specify more precisely what you want the command to do. Many of these options consist of a single letter, making the command brief but not altogether easy to remember. If a command operates on files then the filenames must come after the options.
command [option …] [filename …]