Hi, everybody. In this lesson we'll start to learn Unix Command-Line Interface. During the lesson, I will show a number of basic commands and tools which helps us to work using Unix/Linux command Line interface. At the end of the first lesson, you'll be able to do a lot of useful things like explorer file system, manage files and directories, process data, run scripts, control processes and so on. During this video, we'll take a look at the Command-Line Interface and learn a set of useful commands to work with our system. Let's start from the very beginning. Why are we actually interested in file system exploration? If you wanted to work with data in efficient way, you should have some intuition about how data is actually stored in the computer and how you can interact with the data. In computing, we use the File System to control and manage data stored in device memory. File system used for storing data, controlling data, retrieving data. These are the system you would have stored Information as one large piece of data and would have been extremely complicated to figure out where one piece of information ends and another one begins. When there are specific bits of information stored in memory, how to reach it fast and so on. Basically, a file system helps us to organize data using three main concepts. First, you store data not as one big piece of information, but with separated name these stored files. Second, to store files into specific place called Directories. You have a hierarchy of directories which allows us to structure a set of directories logically. Third, File Systems supports a number of rules used to manage files. Here is speaking about rules of creation, storage, moving, coping and deleting data. We have discussed why we need a File System. Let's move on figure out how we can explore File System. Nowadays probably everybody's used to work in this File System by using one or another File Manager. It can be GNOME's file manager in Unix Operating System, Windows Explorer in Windows Operating System or Finder in Mac and many more. There are quite a lot of graphical applications that allow us to do, allow us to set the functions of files and directories in the file system. To expand the range of possible actions and increase their flexibility, you should use a command-line interface, instead of graphical file manager. The exact way of operating this is command line interface, for example, the list of exact commands, will differ from one operation system to another. But in most cases the logic behind that is similar. In other course you will focus on Unix/Linux Operating System, but you are free to take a look at another command-line interface for a different operation system. If it's vital for you. In Unix/Linux Operating System, you use Bash language, which is a way of interaction with the system. Bash is both a programming language and a command interpreter that typically runs a text window where user types commands and cause actions. Such text windows is called terminal. You can try to find it among the programs installed in your laptop. Along with interpreting commands from the terminal, Bash can also read and execute commands from a file, called Script. You will try both first to run commands in Bash. During the final set of lesson, we will work this Bash terminal and later on we will take a look at Bash script. In this video, I'll tell you about Bash commands which are widely used for system exploration. You can see some commands in this slide. The first command you will learn is called ls. It stands for a list. You use this command for a list content of a directory. If you open a terminal and type ls, you will see the following output. Basically, a list of files and directories stored in the current directory. There also set the functions that you can specify using ls command. For example, you can set the -l option to use a long listing format. It will give us some additional information about the files in directories to store like size, date of last exist and many more. Moreover, you can combine several options to get an example to manage the output. Let's step ls -lh and you will have a long listing format from -l and file size printed in a human readable format from minus harsh. Go deeper, type ls -lSh. Another output will be sorted by size and then by the exist time. There are a lot of nice options to play around. One more thing to be mentioned in that ls command will always not only list the content of the current directory. If you want to see the content of another directory you just need to add path to this is directory to the ls command. For example like this, ls anaconda. The next command we will learn today is cd, which stands for Change Directory. You use this command to move between directories. To jump from the current directory to another one, you should add the path to the target directory to the cd command and you get, cd anaconda. The third command called pwd is name or a working directory. This command will bring the full path of current working directory. Sometime, this is very handy. You can figure out where you currently are or use output of pwd to set the path for ls command. The next command you're about to learn will be related to memory and space, du command displays the disk space used by files. You can run du command in the directory where you would like to explore how much space is used by files. Option minus file share is used to print file sizes, in human readable format, just like you have seen in the above with ls command. And our last command df, is reports the amount of available disk space being used by the file systems. The output you'll have to figure out, how the available space used by file system, how much space is already occupied and how much space is still free. You have already learned five widely used Unix command run interface commands that probably you'll notice, that there are a lot of options available for each command. How can we get more information regarding available option, and their notations? For better help, is the Bash command you use man command, which stands for manual. To reach manual for any Bash command, just type that terminal man and then command name. For example man pwd and you will get the manual for this command. And definitely as you are done, you will be interested in how to close the menu and get back to Bash. Then q stands for quit. That's it. In this video we have discussed the learning file system with Bash programming language and learn five handy Bash commands; ls to list the content of the directory, cd for change in working directory, pwd for print and past as a current working directory, df and du to get the report about the space used by file system and by files. In the next video, you will continue exploring Bash commands and you will learn some commands for managing file system. See you soon.
