Difference between revisions of "BASH/C2/Globbing-and-Export-statement/English-timed"

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|If not, for relevant tutorials please visit our  website which is as shown.
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|If not, for relevant tutorials, please visit our  website which is as shown.
  
 
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| Please note, '''GNU Bash '' 'version 4 or above is recommended to practice this tutorial.
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| Please note, '''GNU Bash '''version 4 or above is recommended to practice this tutorial.
  
 
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|It matches all the files having '''.sh''' '''extension''' in the present directory.
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|It matches all the files having ".sh" '''extension''' in the present directory.
  
 
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|Let me clear the prompt. Now type: '''ls space s asterisk dot sh''' press '''Enter.'''
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|Let me clear the '''prompt'''. Now type: '''ls space s asterisk dot sh''' press '''Enter.'''
  
 
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| We can see that '''s asterisk dot sh''' matches all the files starting with character '''s''' and having '''sh as  extension.  
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| We can see that '''s asterisk dot sh''' matches all the files starting with character '''s''' and having "sh" as  extension.  
  
 
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|And these files have '''sh''' '''extension'''.
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|And these files have "sh" '''extension'''.
  
 
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|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.'''
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|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.'''
  
 
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| This will match all the file-names with '''extension''' '''sh'''
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| This will match all the file-names with '''extension''' "sh"
  
 
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| Observe the output. You will notice that the file names are not starting with character ''''a'''' , ''''b'''' or ''''c''''.
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| Observe the output. You will notice that the file names are not starting with character 'a', 'b' or 'c'.
  
 
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|Let me clear the prompt.
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|Let me clear the '''prompt'''.
  
 
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|  03:19
 
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| Now type: '''ls space opening square bracket capital 'A'  small 'a' closing square bracket asterisk sign dot sh''' press '''Enter.'''
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| Now type: '''ls space opening square bracket capital 'A'  small 'a' closing square bracket asterisk-sign dot sh''' press '''Enter.'''
  
 
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| This will match file names starting with upper and lower case of letter ''''A''''.
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| This will match file names starting with upper and lower case of letter 'A'.
  
 
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| 03:40   
 
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| See the output. All file names starting with upper and lower case ''''A'''' and extension '''sh''' are listed.
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| See the output. All file names starting with upper and lower case 'A' and extension "sh" are listed.
  
 
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| Switch to the '''slides'''.
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|* '''Local variables''' can be used by same '''Shell ''' or by the current '''Shell'''.  
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| '''Local variables''' can be used by same '''Shell ''' or by the current '''Shell'''.  
  
 
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| Switch to the '''Terminal, ''' type: '''myvar equal to sign lion''' press''' Enter.'''
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| Switch to our '''Terminal, ''' type: '''myvar equal to sign lion''' press''' Enter.'''
  
 
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| Now type: '''echo space dollar sign myvar''' press '''Enter.'''
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| Now type: '''echo space dollar-sign myvar''' press '''Enter.'''
  
 
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| Now let's check the value in the variable '''myvar.'''
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| Now, let's check the value in the variable '''myvar.'''
  
 
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| Type: '''echo space dollar sign myvar''' press '''Enter.'''
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| Type: '''echo space dollar-sign myvar''' press '''Enter.'''
  
 
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|Also, the variable '''myvar ''' is ''' local''' only to the previous '''Shell''' and not to current '''Shell'''.
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|Also, the variable '''myvar ''' is ''' local''' only to the previous '''Shell''' and not to the current '''Shell'''.
  
 
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| So, to declare variables '''globally,''' we have to use the '''export command. '''
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| So, to declare variables '''global'''ly, we have to use the '''export command. '''
  
 
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| Let me clear the prompt.
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| Let me clear the '''prompt'''.
  
 
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|  06:15
 
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|  Now type: '''echo space dollar sign myvar'''.  
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|  Now type: '''echo space dollar-sign myvar'''.  
  
 
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| Conducts workshops using spoken tutorials.  
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|* Conducts workshops using spoken tutorials.  
  
 
|-
 
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|  07:08
 
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| Gives certificates to those who pass an online test.
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|* Gives certificates to those who pass an online test.
  
 
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|Spoken Tutorial Project is a part of the "Talk to a Teacher" project.
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|'''Spoken Tutorial''' Project is a part of the '''Talk to a Teacher''' project.
  
 
|-
 
|-

Revision as of 22:03, 9 July 2015

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
00:09 * 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
01:04 # ? (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
06:42 * Export command.
06:44 As an assignment,
06:45 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.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Ranjana, Sandhya.np14

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