BASH/C3/Using-File-Descriptors/English-timed - Revision history

Pratik kamble at 11:33, 23 March 2017

2017-03-23T11:33:08Z

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Sandhya.np14 at 04:18, 14 July 2015

2015-07-14T04:18:44Z

Sandhya.np14 at 18:47, 5 July 2015

2015-07-05T18:47:30Z

Sandhya.np14 at 18:32, 5 July 2015

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Gaurav at 06:28, 29 January 2015

2015-01-29T06:28:34Z

PoojaMoolya at 09:11, 8 December 2014

2014-12-08T09:11:53Z

PoojaMoolya at 07:21, 8 December 2014

2014-12-08T07:21:20Z

Gaurav: Created page with "{|border = 1 | Visual Cue | Narration |- | 00.01 | Dear friends, Welcome to the spoken tutorial on''' Using file descriptors''' |- | 00.08 | In this tutorial, we will..."

2014-11-20T10:12:59Z

Created page with "{|border = 1 | Visual Cue | Narration |- | 00.01 | Dear friends, Welcome to the spoken tutorial on''' Using file descriptors''' |- | 00.08 | In this tutorial, we will..."

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{|border = 1
| Visual Cue
| Narration

|-
| 00.01
| Dear friends, Welcome to the spoken tutorial on''' Using file descriptors'''

|-
| 00.08
| In this tutorial, we will learn to

|-
| 00.11
| * Assign an '''output file descriptor'''

|-
| 00.14
| * Assign an '''input file descriptor'''

|-
| 00.17
| * Close the '''file descriptor (fd)'''

|-
| 00.19
| * With the help of some examples

|-
|00.23
| To follow this tutorial you should have knowledge of '''Shell Scripting''' in''' BASH.'''

|-
| 00.29
| If not, for relevant tutorials please visit our website which is as shown,'''http://www.spoken-tutorial.org'''

|-
| 00.35
| For this tutorial I am using''' '''

|-
| 00.38
| * '''Ubuntu Linux''' 12.04''' '''Operating System

|-
| 00.43
| * '''GNU BASH''' version 4.2

|-
| 00.46
| Please note,''' GNU Bash''' '''version 4''' or above is recommended for practice.

|-
| 00.54
| Let us start with an introduction.

|-
| 00.56
| We have already studied about '''file descriptors''' in the previous tutorial.

|-
| 01.02
| * 0, 1 and 2 are the standard '''file descriptors''' for''' stdin,''' '''stdout''' and '''stderr'''

|-
| 01.15
| * '''File descriptors''' are used for '''i/o redirection'''.

|-
| 01.20
| The syntax to assign a '''file descriptor '''to an output file is:

|-
| 01.25
| '''exec [File descriptor] greater than symbol filename'''

|-
| 01.31
| Let us see an example.

|-
| 01.33
| I have a code file with the name '''fdassign dot sh'''

|-
| 01.43
| The first line is the '''shebang line.'''

|-
| 01.49
| The '''exec''' command replaces the current '''shell process'''.

|-
| 01.56
| It will be executed in the place of the current '''shell '''without creating a new process.

|-
| 02.04
| We know that 0, 1, and 2 are standard '''file descriptors. '''

|-
| 02.09
| For any newly opened file, we have additional '''file descriptors''' from 3 to 9.

|-
| 02.19
| Here, '''3 '''is the '''file descriptor'''.

|-
| 02.22
| This will write the output to the '''output dot txt''' file.

|-
| 02.30
| The string '''"Welcome to BASH learning" '''is sent to the file '''output dot txt'''

|-
| 02.36
| This is done via '''file descriptor 3'''.

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| 02.42
| This is similar to redirecting a string to a file.

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| 02.49
| Each new string will be appended to the file.

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| 02.52
| For example:

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| 02.54
| We will append the current '''system date''' to the''' output dot txt''' file.

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| 03.00
| The syntax is: '''date SPACE greater-than symbol ampersand sign 3'''

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| 03.13
| Here we close the '''file descriptor'''.

|-
| 03.16
| After this line, the '''descriptor '''cannot write anything to the '''output dot txt''' file.

|-
| 03.23
| Let us execute the code and see the output.

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| 03.26
| Open the '''terminal '''using '''CTRL+ALT+T''' keys.

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| 03.34
| Type: '''chmod space plus x space fdassign dot sh'''

|-
| 03.41
| Type: '''dot slash fdassign dot sh'''

|-
| 03.46
| Let us check the output now by typing '''cat space output dot txt'''

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| 03.56
| We can see that the string '''Welcome to BASH learning''' and the current '''system date''' is displayed.

|-
| 04.05
| Let us go back to the editor.

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| 04.11
| Now I will type '''echo '''at the end, after the '''descriptor '''is closed.

|-
| 04.17
| Type: '''echo within double quotes Hi after quotes space greater than symbol ampersand sign 3'''

|-
| 04.31
| Click on '''Save'''.

|-
| 04.35
| Let us execute the script once again and see what happens.

|-
| 04.38
| On the '''terminal''', press the uparrow key twice recall the previous command '''dot slash fdassign dot sh'''

|-
| 04.50
| press '''Enter.'''

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| 04.52
| We see an error

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| 04.55
| '''Bad file descriptor'''

|-
| 04.58
| Let us fix this error.

|-
| 05.00
| Come back to the editor.

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| 05.03
| I will cut the last line of code and paste it below the '''date command'''

|-
| 05.11
| Click on '''Save'''.

|-
| 05.13
| Let us execute the code once again. On the '''terminal'''

|-
| 05.19
| Recall the previous command '''dot slash fdassign.sh'''

|-
| 05.24
| press '''Enter.'''

|-
| 05.26
| Now let us open the '''output dot txt''' file.

|-
| 05.29
| Type: '''cat space output dot txt'''

|-
| 05.41
| We can see the output.

|-
| 05.43
| The string '''Hi '''is displayed at the end.

|-
| 05.49
| Now we will assign the '''file descriptor''' to the input file.

|-
| 05.54
| Let us see an example.

|-
| 05.56
| I have a file named '''fdread dot sh'''

|-
| 06.03
| Let us go through it.

|-
| 06.07
| This is the '''exec command.'''

|-
| 06.13
| Here we will read the file '''output dot txt'''

|-
| 06.19
| The line '''exec 3 greater than symbol output dot txt''' will open the file for reading.

|-
| 06.30
| '''cat command''' will display the content of the file.

|-
| 06.35
| And finally we close the '''file descriptor.'''

|-
| 06.39
| Now let us execute this '''shell script'''.

|-
| 06.42
| On the '''terminal''', let me clear the '''prompt'''.

|-
| 06.47
| Type: '''chmod space plus x space fdread dot sh'''

|-
| 06.55
| Type '''dot slash fdread dot sh'''

|-
| 07.01
| We can see the output on the '''terminal'''.

|-
| 07.05
| The content of '''output dot txt''' file is displayed.

|-
| 07.10
| This brings us to the end of this tutorial.

|-
| 07.13
| Come back to the slides.

|-
| 07.16
| Let us summarize.

|-
| 07.17
| In this tutorial we learnt to,

|-
| 07.19
| * Assign the '''output file descriptor'''

|-
| 07.22
| * Assign the '''input file descriptor'''

|-
| 07.26
| * Close the '''file descriptor'''.

|-
| 07.28
| As an assignment,

|-
| 07.30
| Try to append a few lines to a file '''test dot txt'''using '''file descriptors'''

|-
| 07.36
| Display the content of the file using '''file descriptors'''

|-
| 07.41
| Watch the video available at the link shown below.

|-
| 07.45
| It summarises the Spoken Tutorial project.

|-
| 07.48
| If you do not have good bandwidth, you can download and watch it.

|-
| 07.53
| The Spoken Tutorial Project Team Conducts workshops using spoken tutorials

|-
| 07.58
| Gives certificates to those who pass an online test

|-
| 08.02
| For more details, please write to '''contact@spoken-tutorial.org'''

|-
| 08.10
| Spoken Tutorial Project is a part of the Talk to a Teacher project.

|-
| 08.14
| It is supported by the National Mission on Education through ICT, MHRD, Government of India.

|-
| 08.22
| More information on this Mission is available at the link shown below http://spoken-tutorial.org\NMEICT-Intro

|-
| 08.28
| The script has been contributed by FOSSEE and Spoken-Tutorial teams.

|-
| 08.33
| This is Ashwini Patil from IIT Bombay. Signing off

|-
| 08.37
| Thank you for joining.

|}

@@ Line 393: / Line 393: @@
 |-
 |  08.33
-| This is Ashwini Patil from IIT Bombay, Signing off.
+| This is Ashwini Patil from IIT Bombay, signing off.
 |-

@@ Line 277: / Line 277: @@
 |-
 |  06.19
-| The line '''exec 3 greater than symbol output dot txt''' will open the file for reading.
+| The line '''exec 3 lesser than symbol output dot txt''' will open the file for reading.
 |-

@@ Line 5: / Line 5: @@
 |-
 |   00.01
-|  Dear friends, welcome to the '''spoken tutorial''' on''' Using file descriptors'''.
+|  Dear friends, welcome to the '''spoken tutorial''' on''' Using File Descriptors'''.
 |-
@@ Line 61: / Line 61: @@
 |-
 |  01.02
-| * 0, 1 and 2 are the standard '''file descriptors''' for''' stdin,''' '''stdout''' and '''stderr'''.
+|  0, 1 and 2 are the standard '''file descriptors''' for''' stdin,''' '''stdout''' and '''stderr'''.
 |-
@@ Line 81: / Line 81: @@
 |-
 |  01.33
-| I have a code file with the name '''fdassign dot sh'''.
+| I have a '''code file''' with the name '''fdassign dot sh'''.
 |-
@@ Line 89: / Line 89: @@
 |-
 |  01.49
-|  The '''exec''' command replaces the current '''shell process'''.
+|  The '''"exec"''' command replaces the current '''shell process'''.
 |-
 |  01.56
-| It will be executed in the place of the current '''shell '''without creating a new process.
+| It will be executed in the place of the current '''shell '''without creating a new '''process'''.
 |-
 |  02.04
-| We know that 0, 1, and 2 are standard '''file descriptors. '''
+| We know that 0, 1, and 2 are standard '''file descriptors.'''
 |-
@@ Line 105: / Line 105: @@
 |-
 |  02.19
-| Here, '''3 '''is the '''file descriptor'''.
+| Here, 3 is the '''file descriptor'''.
 |-
@@ Line 113: / Line 113: @@
 |-
 |  02.30
-|  The '''string''' '''"Welcome to BASH learning" '''is sent to the file '''output dot txt'''.
+|  The '''string''' "Welcome to BASH learning" is sent to the file '''output dot txt'''.
 |-
@@ Line 137: / Line 137: @@
 |-
 |  03.00
-| The syntax is: '''date SPACE greater-than symbol ampersand sign 3'''
+| The syntax is: '''date SPACE greater-than symbol ampersand sign 3'''.
 |-
 |  03.13
-|  Here we close the '''file descriptor'''.
+|  Here, we close the '''file descriptor'''.
 |-
@@ Line 165: / Line 165: @@
 |-
 |  03.46
-|  Let us check the '''output''' now by typing '''cat space output dot txt'''
+|  Let us check the '''output''' now by typing '''cat space output dot txt'''.
 |-
 |  03.56
-| We can see that the '''string''' '''Welcome to BASH learning''' and the current '''system date''' is displayed.
+| We can see that the string '''"Welcome to BASH learning"''' and the current '''system date''' is displayed.
 |-
@@ Line 181: / Line 181: @@
 |-
 |  04.17
-| Type: '''echo within double quotes Hi after quotes space greater than symbol ampersand sign 3'''
+| Type: '''echo space''' within double quotes '''Hi''' after quotes '''space''' '''greater than''' symbol '''ampersand''' sign '''3'''
 |-
@@ Line 205: / Line 205: @@
 |-
 |  04.55
-| '''Bad file descriptor'''.
+| '''"Bad file descriptor"'''.
 |-
@@ Line 217: / Line 217: @@
 |-
 |  05.03
-| I will cut the last line of code and paste it below the '''date command'''
+| I will cut the last line of code and paste it below the '''date command'''.
 |-
@@ Line 225: / Line 225: @@
 |-
 |  05.13
-| Let us '''execute''' the '''code''' once again. On the '''terminal'''.
+| Let us '''execute''' the '''code''' once again, on the '''terminal'''.
 |-
@@ Line 249: / Line 249: @@
 |-
 |  05.43
-| The string '''Hi '''is displayed at the end.
+| The string "Hi" is displayed at the end.
 |-
@@ Line 269: / Line 269: @@
 |-
 |  06.07
-|  This is the '''exec command.'''
+|  This is the''' 'exec' '''command.
 |-
@@ Line 281: / Line 281: @@
 |-
 |  06.30
-| '''cat command''' will display the content of the file.
+| ''' 'cat' '''command will display the content of the file.
 |-
 |  06.35
-| And finally we close the '''file descriptor.'''
+| And finally, we close the '''file descriptor.'''
 |-
 | 06.39
-|  Now let us '''execute''' this '''shell script'''.
+|  Now, let us '''execute''' this '''shell script'''.
 |-
@@ Line 325: / Line 325: @@
 |-
 |  07.17
-| In this tutorial, we learnt to:
+| In this tutorial, we learned to:
 |-
@@ Line 349: / Line 349: @@
 |-
 |  07.36
-| Display the content of the file using '''file descriptors'''.
+| Display the contents of the file using '''file descriptors'''.
 |-
@@ Line 385: / Line 385: @@
 |-
 |  08.22
-| More information on this mission is available at the link shown below http://spoken-tutorial.org\NMEICT-Intro
+| More information on this mission is available at the link shown below http://spoken-tutorial.org/NMEICT-Intro
 |-

@@ Line 345: / Line 345: @@
 |-
 |  07.30
-| Try to append a few lines to a file '''test dot txt'''using '''file descriptors'''
+| Try to append a few lines to a file '''test dot txt''' using '''file descriptors'''
 |-

@@ Line 1: / Line 1: @@
 {|border = 1
-|  Visual Cue
+| Time
 |  Narration