Difference between revisions of "BASH/C2/Globbing-and-Export-statement/English-timed"
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| − | | ''Filename'' or ''pathname'' expansion carried by '''BASH''' is known as '''Globbing'''. | + | | '''Filename''' or '''pathname''' expansion carried by '''BASH''' is known as '''Globbing'''. |
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| − | | | + | |*(asterisk) and '''?''' (Question mark). |
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Latest revision as of 15:35, 23 March 2017
| Time | Narration |
| 00:01 | Welcome to this spoken tutorial on Globbing and Export command. |
| 00:06 | In this tutorial, we will learn about: |
| 00:08 | Globbing, export command. |
| 00:11 | To follow this tutorial, You should be familiar with Linux Operating System. |
| 00:18 | If not, for relevant tutorials, please visit our website which is as shown. |
| 00:24 | For this tutorial, I am using: |
| 00:27 | Ubuntu Linux 12.04 OS and |
| 00:31 | GNU Bash version 4.1.10 |
| 00:35 | Please note, GNU Bash version 4 or above is recommended to practice this tutorial. |
| 00:43 | Let us start with an introduction to globbing. |
| 00:46 | Filename or pathname expansion carried by BASH is known as Globbing. |
| 00:52 | Globbing recognizes and expands wildcards. |
| 00:57 | It also interprets standard wildcard characters like- |
| 01:02 | *(asterisk) and ? (Question mark). |
| 01:05 | Let us understand this with the help of an example. |
| 01:09 | Open the terminal window by pressing Ctrl+Alt and T keys simultaneously on your keyboard. |
| 01:18 | On the Terminal, type: ls space asterisk dot sh press Enter. |
| 01:27 | It matches all the files having ".sh" extension in the present directory. |
| 01:34 | Here, we can see that all the sh files are listed. |
| 01:40 | Let me clear the prompt. Now type: ls space s asterisk dot sh press Enter. |
| 01:51 | We can see that s asterisk dot sh matches all the files starting with character s and having "sh" as extension. |
| 02:02 | Let's move on ... |
| 02:04 | Now, type: ls space opening square bracket a hyphen c closing square bracket asterisk dot sh press Enter. |
| 02:19 | This will match and display the files starting with letter 'a' or 'b' or 'c.' |
| 02:26 | Observe the output. |
| 02:28 | We see a list of all files starting with character 'a' or 'b' or 'c.' |
| 02:35 | And these files have "sh" extension. |
| 02:39 | Now, let's go ahead and type: ls space opening square bracket caret-sign a hyphen c closing square bracket asterisk dot sh press Enter. |
| 02:55 | This will match all the file-names with extension "sh" |
| 03:00 | but will omit those starting with character as 'a' OR 'b' OR 'c'. |
| 03:07 | Observe the output. You will notice that the file names are not starting with character 'a', 'b' or 'c'. |
| 03:16 | Let me clear the prompt. |
| 03:19 | Now type: ls space opening square bracket capital 'A' small 'a' closing square bracket asterisk-sign dot sh press Enter. |
| 03:34 | This will match file names starting with upper and lower case of letter 'A'. |
| 03:40 | See the output. All file names starting with upper and lower case 'A' and extension "sh" are listed. |
| 03:49 | Now let's see the Export command in BASH. |
| 03:53 | Switch to our slides. |
| 03:55 | In Bash, variables are local to their own Shell. |
| 04:00 | Local variables can be used by same Shell or by the current Shell. |
| 04:06 | Export command- exports a variable or a function to the environment of all child processes. |
| 04:15 | Can also change a local variable to a global variable. |
| 04:20 | We will try to understand this with an example. |
| 04:24 | Switch to our Terminal, type: myvar equal to sign lion press Enter. |
| 04:34 | Now type: echo space dollar-sign myvar press Enter. |
| 04:41 | lion is printed. |
| 04:44 | This is the value assigned to the variable myvar. |
| 04:48 | Now, let's navigate to a new Shell. |
| 04:51 | To go to a new Shell, we can either open a new Terminal or type: slash bin slash bash press Enter. |
| 05:03 | Now, let's check the value in the variable myvar. |
| 05:07 | Type: echo space dollar-sign myvar press Enter. |
| 05:15 | An empty line is printed. |
| 05:17 | This means that the value assigned to variable myvar was not transferred to this Shell. |
| 05:24 | Also, the variable myvar is local only to the previous Shell and not to the current Shell. |
| 05:32 | We will type exit to get back to our previous Shell. |
| 05:36 | So, to declare variables globally, we have to use the export command. |
| 05:43 | Let's learn how. |
| 05:46 | Type: export space myvar equal to sign lion press Enter. |
| 05:55 | Now type: echo space dollar sign myvar press Enter. |
| 06:02 | lion is displayed. |
| 06:05 | Let's navigate to another Shell. Type: slash bin slash bash press Enter. |
| 06:13 | Let me clear the prompt. |
| 06:15 | Now type: echo space dollar-sign myvar. |
| 06:22 | lion is displayed |
| 06:25 | This is because we have declared the variable myvar globally using the export command. |
| 06:33 | This brings us to the end of this tutorial. |
| 06:36 | Let us summarize. Come back to our slides. |
| 06:39 | In this tutorial, we learnt: |
| 06:41 | Globbing, Export command. |
| 06:44 | As an assignment, Write a Bash script to do all the operations discussed under globbing. |
| 06:51 | Watch the video available at the link shown below. |
| 06:54 | It summarizes the Spoken Tutorial project. |
| 06:57 | If you do not have good bandwidth, you can download and watch it. |
| 07:02 | The Spoken-Tutorial Project team: |
| 07:05 | Conducts workshops using spoken tutorials. |
| 07:08 | Gives certificates to those who pass an online test. |
| 07:12 | For more details, please write to contact@spoken-tutorial.org |
| 07:20 | Spoken Tutorial Project is a part of the Talk to a Teacher project. |
| 07:24 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 07:31 | More information on this mission is available at the link shown below. |
| 07:37 | The script has been contributed by FOSSEE and Spoken-Tutorial team. |
| 07:42 | This is Ashwini from IIT Bombay, signing off. |
| 07:47 | Thank you for joining. |
