Introduction to Linux and Bash
A brief introduction to Linux and Bash on the CCB cluster.
What is Linux?
Linux is an operating system (OS), like Microsoft Windows (MS Windows) and macOS.
However, Linux is open source and free of cost.
Linux and macOS are different, but share a large number of commands as macOS is based on BSD (Berkeley Standard Distribution) which is similar to Linux but not Linux.
More technical differences include:
- File names are case-sensitive in Linux (and macOS) while they are not in MS Windows.
- File paths are separated by
/(forward slash) on Linux (and macOS), while they are separated by\(back slash) on MS Windows.
The Linux file system
In the Linux filesystem, everything is a file.
A directory is a file that contains the list of files and directories that it contains.
As a result, files organised in a tree structure.
The first directory in that tree is called ‘root’,
and it is represented by the symbol / (forward slash).
The schema below illustrates some of the core directories and files that make up a typical Linux filesystem.
What is Bash?
Bash (Bourne Again Shell) is the shell, or command language interpreter, for the GNU/Linux operating system. In other words, it is the programming language that is used to issue commands to the operating system from the Terminal application.
How do I use Bash?
If you have gone through the earlier section Connect to CCB, then congratulations: you have been using Bash already!
From the moment you typed commands such as ssh and passwd in the Terminal
application, you have been working in a Bash session, and issuing commands
to the operating system from that Bash session.
Once logged into the CCB cluster, the Terminal application gives you access to the Linux shell – i.e., the command line interface – where you can type commands that are given to the operating system and executed in the current Bash environment.
Where do I go from here?
Once connected to the CCB cluster, you can use built-in Bash commands to:
- list and navigate directories in the filesystem
- create, edit, remove, open and execute files
- create and remove directories
- …and much more!
In the following pages, this documentation introduces commonly used built-in Bash commands and options, and describing best practices on the CCB cluster.