Difference between revisions of "BASH/C2/Introduction-to-BASH-Shell-Scripting/English-timed"
From Script | Spoken-Tutorial
| Line 357: | Line 357: | ||
|- | |- | ||
|06:48 | |06:48 | ||
| − | | | + | |Different types of '''Shells''' |
|- | |- | ||
Latest revision as of 15:19, 23 March 2017
| Time | Narration |
| 00:01 | Dear friends, welcome to the Spoken tutorial on Introduction to BASH shell scripting. |
| 00:08 | In this tutorial, we will learn: |
| 00:10 | About different types of Shells |
| 00:13 | To write a Bash Shell script and |
| 00:16 | To execute it. |
| 00:18 | To follow this tutorial, you should be familiar with Linux Operating System. |
| 00:25 | If not, then for relevant Linux tutorials, please visit our website which is as shown. |
| 00:32 | For this tutorial, I am using: |
| 00:35 | Ubuntu Linux 12.04 OS and |
| 00:39 | GNU Bash version 4.1.10. |
| 00:43 | Please note, GNU Bash version 4 or above is recommended for practice. |
| 00:50 | Let us start with an introduction. |
| 00:53 | We will see what a Bash Shell is. |
| 00:56 | Bash Shell is a command language interpreter that executes commands. |
| 01:02 | These commands are read from the standard input device. |
| 01:07 | The input device can be- |
| 01:09 | your keyboard |
| 01:11 | or a simple text file. |
| 01:14 | Let me show you what is a Bash Shell. |
| 01:16 | Open the terminal window by pressing Ctrl+Alt+T keys simultaneously on your keyboard . |
| 01:24 | This will open the Gnome terminal. |
| 01:27 | To check which type of shell we are using, type: echo space dollar sign SHELL (in capital). |
| 01:38 | Press Enter. |
| 01:40 | You will see the output printed on the next line as: slash bin slash bash. |
| 01:47 | This indicates that we are using the Bash Shell. |
| 01:51 | Now, let us know different types of Shells available. |
| 01:56 | Let us switch back to our slides. Bourne Shell- |
| 02:00 | This was original UNIX shell written by Stephen Bourne. |
| 02:06 | It lacked interactivity provided by most modern shells today. |
| 02:11 | C Shell-It provides features lacking in Bourne Shell . |
| 02:16 | K Shell- It was created by David Korn. |
| 02:20 | It has features of both, B Shell and C Shell along with some additional features. |
| 02:27 | Bash Shell- |
| 02:30 | The Bash Shell was developed by GNU Project. |
| 02:32 | It is based on B Shell language. |
| 02:35 | It has features of C and K Shells. |
| 02:40 | TC Shell-It is the default Shell of FreeBSD and its descendants. |
| 02:46 | Z shell- |
| 02:49 | It is a Shell designed for interactive use. |
| 02:52 | It has many useful features of ksh, bash and tcsh. |
| 02:58 | Now let us see what a Bash Shell script is. |
| 03:02 | The Bash Shell script contains a series of Bash commands in plain text file. |
| 03:08 | It tells the Shell to execute this text file instead of typing the commands. |
| 03:15 | Let us see how to write a simple Bash script. |
| 03:20 | We will test the echo command which will print Hello World on the terminal. |
| 03:25 | Go back to the terminal. |
| 03:29 | Now, type: echo space within double quotes Hello world |
| 03:35 | and press Enter. |
| 03:37 | This prints Hello World on the terminal. |
| 03:40 | The command worked as expected. |
| 03:43 | Now, what if we want to use this command in a file? |
| 03:47 | Just put this command in a file and execute that file. |
| 03:52 | I will use gedit text-editor for this purpose. |
| 03:57 | You are free to use your favorite text-editor. |
| 04:00 | I want to create my file on the Desktop. |
| 04:03 | So, type: cd space Desktop |
| 04:07 | Press Enter. |
| 04:09 | Now, type: gedit space hello underscore world dot sh space &(ampersand sign). |
| 04:20 | gedit is the text editor. 'Hello underscore world dot sh' is the file name and |
| 04:27 | we use the & (ampersand) to free up the prompt. |
| 04:32 | Now press Enter.We have opened a new file named hello_world.sh using gedit. |
| 04:40 | Now, type: hash exclamation mark front slash bin front slash bash |
| 04:47 | This is the first line of every bash script. |
| 04:51 | It is called as shebang or bang line. |
| 04:55 | Press Enter. |
| 04:57 | Now, let's add a comment to the file by typing: |
| 05:00 | hash space My first Bash script |
| 05:06 | Remember that any line after hash is treated as a comment. |
| 05:11 | And comments are ignored by the Bash interpreter. |
| 05:15 | Now we can add the command which we used earlier. |
| 05:19 | Press Enter and type: echo space within double quotes Hello world. |
| 05:27 | Press Enter.Type: echo space dollar-sign SHELL (in Capital) |
| 05:34 | press Enter.Type: echo space backtick date backtick |
| 05:41 | backtick symbol is present on the key which has tilde character. |
| 05:47 | Now, click on Save to save the file. |
| 05:50 | Let us execute. Come back to our terminal. |
| 05:55 | First, we have to make the file executable. |
| 05:58 | For this, type: chmod space plus x space hello underscore world dot sh |
| 06:09 | and press Enter. |
| 06:12 | Now, type: |
| 06:14 | dot slash hello underscore world dot sh |
| 06:19 | Press Enter. |
| 06:22 | You can see Hello World is displayed on the terminal. |
| 06:27 | The shell type is displayed on the next line. i.e slash bin slash bash |
| 06:32 | and day, month, time, time zone and year are displayed. |
| 06:38 | The output may vary depending on the system. |
| 06:43 | Let us go back to our slides and summarize. |
| 06:46 | In this tutorial, we have learnt about: |
| 06:48 | Different types of Shells |
| 06:50 | Bash Shell .Bash Shell script. |
| 06:52 | To write a simple Shell script and to execute the script. |
| 06:57 | As an assignment- write a simple script to display the message -“Welcome to Bash learning” |
| 07:03 | and “***************” (asterisks) on separate line. |
| 07:06 | Watch the video available at the link shown below. |
| 07:10 | It summarizes the Spoken-Tutorial project. |
| 07:13 | If you do not have good bandwidth, you can download and watch it. |
| 07:17 | The Spoken-Tutorial Project team: |
| 07:20 | Conducts workshops using spoken tutorials. |
| 07:22 | Gives certificates to those who pass an online test. |
| 07:26 | For more details, please write to contact@spoken-tutorial.org |
| 07:34 | Spoken Tutorial Project is a part of the "Talk to a Teacher" project. |
| 07:39 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 07:45 | More information on this mission is available at the link shown below. http://spoken-tutorial.org/NMEICT-Intro |
| 07:51 | The script has been contributed by FOSSEE and Spoken-Tutorial teams. |
| 07:56 | This is Ashwini Patil from IIT Bombay, signing off. Thank you for joining. |
