Difference between revisions of "BOSS-Linux/C3/Basics-of-awk/English-timed"

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Line 18: Line 18:
 
| 00:12
 
| 00:12
 
| To record this tutorial, I am using
 
| To record this tutorial, I am using
−
*Ubuntu Linux 12.04 OS
+
* Linux Operating system
 
*GNU BASH v. 4.2.24
 
*GNU BASH v. 4.2.24
  
 
|-
 
|-
−
| 00:23
+
| 00:21
 
| Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
 
| Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
  
Line 30: Line 30:
  
 
|-
 
|-
−
| 00:33
+
| 00:32
 
| The''' awk''' command is a very powerful text manipulation tool.
 
| The''' awk''' command is a very powerful text manipulation tool.
  
 
|-
 
|-
−
| 00:38
+
| 00:36
 
| It is named after its authors, '''Aho, Weinberger''' and '''Kernighan'''.
 
| It is named after its authors, '''Aho, Weinberger''' and '''Kernighan'''.
  
 
|-
 
|-
−
| 00:44
+
| 00:42
 
| It can perform several functions.  
 
| It can perform several functions.  
  
Line 46: Line 46:
  
 
|-
 
|-
−
| 00:51
+
| 00:49
 
| So, it can easily access and edit the individual fields of the record.
 
| So, it can easily access and edit the individual fields of the record.
  
Line 54: Line 54:
  
 
|-
 
|-
−
| 00:59
+
| 00:58
 
| For demonstration purpose, we use the''' awkdemo.txt '''file.  
 
| For demonstration purpose, we use the''' awkdemo.txt '''file.  
  
 
|-
 
|-
−
| 01:04
+
| 01:03
 
| Let us see the contents of '''awkdemo.txt''' file.
 
| Let us see the contents of '''awkdemo.txt''' file.
  
 
|-
 
|-
−
| 01:09
+
| 01:07
−
| Now open the '''terminal''' by pressing
+
| Now open the '''terminal''' window
−
'''CTRL + ALT''' and '''T''' keys simultaneosuly on your keyboard.
+
  
 
|-
 
|-
−
| 01:17
+
| 01:10
 
| Let us see how to print using '''awk command.'''  
 
| Let us see how to print using '''awk command.'''  
  
 
|-
 
|-
−
| 01:22
+
| 01:15
−
| Type:
+
| Type: '''awk space''' (within single quote) (front slash) ‘'''/Pass '''(front slash)'''/'''(opening curly bracket) '''{print (closing curly bracket)}''' (after the  quotes) '''space awkdemo.txt'''  
−
'''awk space''' (within single quote) (front slash) ‘'''/Pass '''(front slash)'''/'''(opening curly bracket) '''{print (closing curly bracket)}''' (after the  quotes) '''space awkdemo.txt'''  
+
  
 
|-
 
|-
−
| 01:38
+
| 01:32
 
| Press '''Enter'''
 
| Press '''Enter'''
  
 
|-
 
|-
−
| 01:40
+
| 01:34
−
|Here '''Pass''' is the selection criterion.  
+
|Here '''Pass''' is the selection criteria.  
  
 
|-
 
|-
−
| 01:44
+
| 01:38
 
| All the lines of the '''awkdemo''' where '''Pass''' occurs are printed.  
 
| All the lines of the '''awkdemo''' where '''Pass''' occurs are printed.  
  
 
|-
 
|-
−
| 01:49
+
| 01:43
 
| The action here is print.  
 
| The action here is print.  
  
 
|-
 
|-
−
| 01:52
+
| 01:46
 
| We can also use '''regular expressions''' in '''awk'''
 
| We can also use '''regular expressions''' in '''awk'''
  
 
|-
 
|-
−
| 01:56
+
| 01:50
 
| Say we want to print records of students with name '''Mira.'''
 
| Say we want to print records of students with name '''Mira.'''
  
 
|-
 
|-
−
| 02:01
+
| 01:55
−
| We would type:
+
| We would type: '''awk space '/M opening square bracket ei closing square bracket asterisk sign ra asterisk sign front slash opening curly bracket  print closing curly bracket  after the quoates space awkdemo.txt'''
−
'''awk space '/M opening square bracket [ ei closing square bracket ]*ra */{ print}' space awkdemo.txt'''
+
  
 
|-
 
|-
−
| 02:27
+
| 02:20
 
| Press '''Enter.'''
 
| Press '''Enter.'''
  
 
|-
 
|-
−
| 02:29
+
| 02:22
−
| '''"*"'''  will give one or more occurrences of previous character.
+
| '''"*(asterisk)"'''  will give one or more occurrences of previous character.
  
 
|-
 
|-
−
| 02:33
+
| 02:27
 
| Thus entries with more than one occurrence for '''i, e''' and '''a''' will be listed.
 
| Thus entries with more than one occurrence for '''i, e''' and '''a''' will be listed.
  
 
|-
 
|-
−
| 02:40
+
| 02:34
 
| For example  
 
| For example  
  
 
|-
 
|-
−
| 02:42
+
| 02:35
−
| *Mira
+
| Mira (with 'M'  'I'  'R'  'A')
  
 
|-
 
|-
−
|02:45
+
|02:38
−
| *Meera
+
| Meera(with 'M'  'E'  'E'  'R'  'A')
  
 
|-
 
|-
−
| 02:47
+
| 02:41
−
| *Meeraa
+
| *Meeraa(with M E E R A A )
  
 
|-
 
|-
−
| 02:52
+
| 02:45
 
| '''awk''' supports the '''extended regular expressions (ERE)'''.
 
| '''awk''' supports the '''extended regular expressions (ERE)'''.
  
 
|-
 
|-
−
| 02:58
+
| 02:51
 
| Which means we can match multiple patterns separated by a '''PIPE'''.
 
| Which means we can match multiple patterns separated by a '''PIPE'''.
 +
 
|-
 
|-
−
|03:03
+
|02:56
 
|Let me clear the promt
 
|Let me clear the promt
  
 
|-
 
|-
−
|03:05
+
|02:59
 
|Now type:
 
|Now type:
  
 
|-
 
|-
−
| 03:06
+
| 03:00
 
| '''awk space (in single quotes)(front slash) ‘/civil(PIPE) '''|electrical '''(front slash)'''space (open curly brackets)/{print}(close curly brackets) after the quotes space'''awkdemo.txt'''
 
| '''awk space (in single quotes)(front slash) ‘/civil(PIPE) '''|electrical '''(front slash)'''space (open curly brackets)/{print}(close curly brackets) after the quotes space'''awkdemo.txt'''
  
 
|-
 
|-
−
| 03:23
+
| 03:18
 
| Press '''Enter.'''
 
| Press '''Enter.'''
  
 
|-
 
|-
−
| 03:26
+
| 03:19
 
| Now entries for both '''civil''' and '''electrical''' are given.
 
| Now entries for both '''civil''' and '''electrical''' are given.
  
 
|-
 
|-
−
| 03:31
+
| 03:24
 
|  Let us go back to our slides.  
 
|  Let us go back to our slides.  
  
 
|-
 
|-
−
| 03:34
+
| 03:28
 
| Parameters '''awk''' has some special parameters to identify individual fields of a line.  
 
| Parameters '''awk''' has some special parameters to identify individual fields of a line.  
  
 
|-
 
|-
−
| 03:41
+
| 03:36
 
| '''$1(Dollar 1)''' would indicate the first field.  
 
| '''$1(Dollar 1)''' would indicate the first field.  
  
 
|-
 
|-
−
| 03:45
+
| 03:40
 
| Similarly we can have '''$2, $3''' and so on for respective fields.  
 
| Similarly we can have '''$2, $3''' and so on for respective fields.  
  
 
|-
 
|-
−
| 03:53
+
| 03:47
 
| '''$0''' represents the entire line.
 
| '''$0''' represents the entire line.
  
 
|-
 
|-
−
|03:56
+
|03:50
 
|come back to our terminal
 
|come back to our terminal
  
 
|-
 
|-
−
| 03:59
+
| 03:52
 
|Note that each word is separated by '''PIPE''' in the file '''awkdemo.txt.'''
 
|Note that each word is separated by '''PIPE''' in the file '''awkdemo.txt.'''
  
 
|-
 
|-
−
| 04:05
+
| 03:59
 
| In this case '''PIPE '''is called a '''delimiter.'''
 
| In this case '''PIPE '''is called a '''delimiter.'''
  
 
|-
 
|-
−
| 04:09
+
| 04:03
 
| A '''delimiter''' separates words from each other.
 
| A '''delimiter''' separates words from each other.
  
 
|-
 
|-
−
| 04:13
+
| 04:06
 
| A '''delimiter''' can also be a single '''whitespace. '''
 
| A '''delimiter''' can also be a single '''whitespace. '''
  
 
|-
 
|-
−
| 04:16
+
| 04:11
 
| To specify a '''delimiter''', we have to give '''- capital F '''flag followed by a '''delimiter'''.
 
| To specify a '''delimiter''', we have to give '''- capital F '''flag followed by a '''delimiter'''.
  
 
|-
 
|-
−
|04:24
+
|04:18
 
| Let us see  
 
| Let us see  
  
 
|-
 
|-
−
| 04:25
+
| 04:19
−
| Type '''awk space minus capital F space''' within double quotes''' PIPE space''' within single quote '''front slash civil PIPE electrical front slash ''' within curly braces''' print space dollar0 space awkdemo.txt'''
+
| Type '''awk space minus capital F space''' within double quotes''' PIPE space''' within single quote '''front slash civil PIPE electrical front slash ''' opening curly bracket''' print space dollar0 closing curly braket  after the quotes space awkdemo.txt'''
  
 
|-
 
|-
−
| 04:51
+
| 04:44
 
| Press '''Enter'''
 
| Press '''Enter'''
  
 
|-
 
|-
−
| 04:53
+
| 04:46
 
| This print the entire line since we have used '''$0.'''
 
| This print the entire line since we have used '''$0.'''
  
 
|-
 
|-
−
| 04:58
+
| 04:52
 
| Notice that, '''names''' and '''stream of students''' are the second and third fields.
 
| Notice that, '''names''' and '''stream of students''' are the second and third fields.
  
 
|-
 
|-
−
| 05:04
+
| 04:58
 
|Say we only want to print two fields.
 
|Say we only want to print two fields.
  
 
|-
 
|-
−
| 05:08
+
| 05:01
 
| We will replace '''$0''' with '''$2 and$3''' in the above command.
 
| We will replace '''$0''' with '''$2 and$3''' in the above command.
  
 
|-
 
|-
−
| 05:15
+
| 05:09
 
| Press '''Enter '''
 
| Press '''Enter '''
  
 
|-
 
|-
−
| 05:18
+
| 05:11
 
| Only two fields are shown.
 
| Only two fields are shown.
  
 
|-
 
|-
−
| 05:21
+
| 05:14
 
| Though it gives the right result, the display is all jagged and unformatted.  
 
| Though it gives the right result, the display is all jagged and unformatted.  
  
 
|-
 
|-
−
| 05:26
+
| 05:20
 
|  We can provide formatted output by using the '''C''' style '''printf '''statement.  
 
|  We can provide formatted output by using the '''C''' style '''printf '''statement.  
  
 
|-
 
|-
−
| 05:32
+
| 05:26
 
| We can also provide a serial number by using a builtin variable '''NR'''.  
 
| We can also provide a serial number by using a builtin variable '''NR'''.  
  
 
|-
 
|-
−
| 05:40
+
| 05:33
 
| We will see more about builtin variables later.
 
| We will see more about builtin variables later.
  
 
|-
 
|-
−
| 05:44
+
| 05:37
−
| Now Type
+
| Now Type '''awk''' space '''minus capital F within double quotes (Pipe)”''' after the double quotes space ''''front slash Pass front slash opening curly bracket printf within double quotes  percentage  sign 4d space percentage  sign -25s space percentage  sign  minus 15s space backslash n”,''' after the double quotes  '''NR,$2,$3 closing curly bracket'''' after the single quote space '''awkdemo.txt'''  
−
'''awk''' space '''-F”|”''' space ''''/Pass/{printf “%4d %-25s %-15s \n”,''' '''NR,$2,$3 }'''' space '''awkdemo.txt'''  
+
  
 
|-
 
|-
−
| 06:33
+
| 06:25
−
| '''Press Enter.'''
+
| Press '''Enter.'''
  
 
|-
 
|-
−
| 06:34
+
| 06:28
 
| We see the difference.
 
| We see the difference.
  
 
|-
 
|-
−
| 06:37
+
| 06:30
 
| Here the '''NR''' stands for number of records.  
 
| Here the '''NR''' stands for number of records.  
  
 
|-
 
|-
−
| 06:41
+
| 06:33
 
| Records are '''integers''', hence we have written''' %d'''.  
 
| Records are '''integers''', hence we have written''' %d'''.  
  
 
|-
 
|-
−
| 06:45
+
| 06:37
 
| '''Name''' and '''Stream''' are '''strings'''. So we have used '''%s'''.  
 
| '''Name''' and '''Stream''' are '''strings'''. So we have used '''%s'''.  
  
 
|-
 
|-
−
| 06:50
+
| 06:43
 
| Here '''25s''' will reserve 25 spaces for '''Name''' field.
 
| Here '''25s''' will reserve 25 spaces for '''Name''' field.
  
 
|-
 
|-
−
| 06:55
+
| 06:48
 
| '''15s''' will reserve 15 spaces for '''Stream''' field.
 
| '''15s''' will reserve 15 spaces for '''Stream''' field.
  
 
|-
 
|-
−
| 07:01
+
| 06:54
 
| The '''minus sign''' is used to left justify the output.
 
| The '''minus sign''' is used to left justify the output.
  
 
|-
 
|-
−
| 07:05
+
| 06:58
 
| This brings us to the end of this tutorial.
 
| This brings us to the end of this tutorial.
  
 
|-
 
|-
−
| 07:08
+
| 07:01
 
| Let us move back to our slides.
 
| Let us move back to our slides.
  
 
|-
 
|-
−
| 07:10
+
| 07:04
 
| Let us summarize.
 
| Let us summarize.
  
 
|-
 
|-
−
| 07:11
+
| 07:05
−
| In this tutorial we learnt To print using awk
+
| In this tutorial we learnt To print using '''awk'''
  
 
|-
 
|-
−
| 07:16
+
| 07:10
−
| Regular expression in awk To list the enteries for a paritcular stream
+
| Regular expression in '''awk'''. To list the enteries for a paritcular stream
  
 
|-
 
|-
−
| 07:21
+
| 07:15
 
| To list only the second and the third fileds
 
| To list only the second and the third fileds
  
 
|-
 
|-
−
| 07:24
+
| 07:18
 
| To display a formatted output
 
| To display a formatted output
  
 
|-
 
|-
−
| 07:28
+
| 07:19
 
| As an assignment  
 
| As an assignment  
  
 
|-
 
|-
−
|07:29
+
|07:22
 
| Display roll no., stream and marks of Ankti Saraf
 
| Display roll no., stream and marks of Ankti Saraf
  
 
|-
 
|-
−
| 07:34
+
| 07:27
 
|  Watch the video available at the link shown below
 
|  Watch the video available at the link shown below
  
 
|-
 
|-
−
| 07:37
+
| 07:30
 
| It summarises the Spoken Tutorial project
 
| It summarises the Spoken Tutorial project
  
 
|-
 
|-
−
| 07:40
+
| 07:33
 
| If you do not have good bandwidth, you can download and watch it
 
| If you do not have good bandwidth, you can download and watch it
  
 
|-
 
|-
−
|07:45
+
|07:37
 
|The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
 
|The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
  
 
|-
 
|-
−
| 07:48
+
| 07:42
 
| Gives certificates to those who pass an online test
 
| Gives certificates to those who pass an online test
  
 
|-
 
|-
−
| 07:52
+
| 07:45
 
| For more details, please write to contact@spoken-tutorial.org
 
| For more details, please write to contact@spoken-tutorial.org
  
 
|-
 
|-
−
| 07:58
+
| 07:51
 
|Spoken Tutorial Project is a part of the Talk to a Teacher project
 
|Spoken Tutorial Project is a part of the Talk to a Teacher project
  
 
|-
 
|-
−
| 08:01
+
| 07:55
 
| It is supported by the National Mission on Education through ICT,MHRD,Government of India
 
| It is supported by the National Mission on Education through ICT,MHRD,Government of India
  
 
|-
 
|-
−
| 08:07
+
| 08:02
 
| More information on this Mission is available at:  [http://spokentutorial.org\NMEICT-Intro]
 
| More information on this Mission is available at:  [http://spokentutorial.org\NMEICT-Intro]
  
 
|-
 
|-
−
| 08:12
+
| 08:07
 
|This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.
 
|This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.
  
 
|}
 
|}

Revision as of 13:08, 12 February 2015

Time Narration
00:01 Welcome to the spoken tutorial on the awk command.
00:05 In this tutorial we will learn, awk command.
00:09 We will do this through some examples.
00:12 To record this tutorial, I am using
  • Linux Operating system
  • GNU BASH v. 4.2.24
00:21 Please note, GNU Bash version 4 or above is recommended to practice this tutorial.
00:29 Let us start with an introduction to awk.
00:32 The awk command is a very powerful text manipulation tool.
00:36 It is named after its authors, Aho, Weinberger and Kernighan.
00:42 It can perform several functions.
00:46 It operates at the field level of a record.
00:49 So, it can easily access and edit the individual fields of the record.
00:56 Let us see some examples.
00:58 For demonstration purpose, we use the awkdemo.txt file.
01:03 Let us see the contents of awkdemo.txt file.
01:07 Now open the terminal window
01:10 Let us see how to print using awk command.
01:15 Type: awk space (within single quote) (front slash) ‘/Pass (front slash)/(opening curly bracket) {print (closing curly bracket)} (after the quotes) space awkdemo.txt
01:32 Press Enter
01:34 Here Pass is the selection criteria.
01:38 All the lines of the awkdemo where Pass occurs are printed.
01:43 The action here is print.
01:46 We can also use regular expressions in awk
01:50 Say we want to print records of students with name Mira.
01:55 We would type: awk space '/M opening square bracket ei closing square bracket asterisk sign ra asterisk sign front slash opening curly bracket print closing curly bracket after the quoates space awkdemo.txt
02:20 Press Enter.
02:22 "*(asterisk)" will give one or more occurrences of previous character.
02:27 Thus entries with more than one occurrence for i, e and a will be listed.
02:34 For example
02:35 Mira (with 'M' 'I' 'R' 'A')
02:38 Meera(with 'M' 'E' 'E' 'R' 'A')
02:41 *Meeraa(with M E E R A A )
02:45 awk supports the extended regular expressions (ERE).
02:51 Which means we can match multiple patterns separated by a PIPE.
02:56 Let me clear the promt
02:59 Now type:
03:00 electrical (front slash)space (open curly brackets)/{print}(close curly brackets) after the quotes spaceawkdemo.txt
03:18 Press Enter.
03:19 Now entries for both civil and electrical are given.
03:24 Let us go back to our slides.
03:28 Parameters awk has some special parameters to identify individual fields of a line.
03:36 $1(Dollar 1) would indicate the first field.
03:40 Similarly we can have $2, $3 and so on for respective fields.
03:47 $0 represents the entire line.
03:50 come back to our terminal
03:52 Note that each word is separated by PIPE in the file awkdemo.txt.
03:59 In this case PIPE is called a delimiter.
04:03 A delimiter separates words from each other.
04:06 A delimiter can also be a single whitespace.
04:11 To specify a delimiter, we have to give - capital F flag followed by a delimiter.
04:18 Let us see
04:19 Type awk space minus capital F space within double quotes PIPE space within single quote front slash civil PIPE electrical front slash opening curly bracket print space dollar0 closing curly braket after the quotes space awkdemo.txt
04:44 Press Enter
04:46 This print the entire line since we have used $0.
04:52 Notice that, names and stream of students are the second and third fields.
04:58 Say we only want to print two fields.
05:01 We will replace $0 with $2 and$3 in the above command.
05:09 Press Enter
05:11 Only two fields are shown.
05:14 Though it gives the right result, the display is all jagged and unformatted.
05:20 We can provide formatted output by using the C style printf statement.
05:26 We can also provide a serial number by using a builtin variable NR.
05:33 We will see more about builtin variables later.
05:37 Now Type awk space minus capital F within double quotes (Pipe)” after the double quotes space 'front slash Pass front slash opening curly bracket printf within double quotes percentage sign 4d space percentage sign -25s space percentage sign minus 15s space backslash n”, after the double quotes NR,$2,$3 closing curly bracket' after the single quote space awkdemo.txt
06:25 Press Enter.
06:28 We see the difference.
06:30 Here the NR stands for number of records.
06:33 Records are integers, hence we have written %d.
06:37 Name and Stream are strings. So we have used %s.
06:43 Here 25s will reserve 25 spaces for Name field.
06:48 15s will reserve 15 spaces for Stream field.
06:54 The minus sign is used to left justify the output.
06:58 This brings us to the end of this tutorial.
07:01 Let us move back to our slides.
07:04 Let us summarize.
07:05 In this tutorial we learnt To print using awk
07:10 Regular expression in awk. To list the enteries for a paritcular stream
07:15 To list only the second and the third fileds
07:18 To display a formatted output
07:19 As an assignment
07:22 Display roll no., stream and marks of Ankti Saraf
07:27 Watch the video available at the link shown below
07:30 It summarises the Spoken Tutorial project
07:33 If you do not have good bandwidth, you can download and watch it
07:37 The Spoken Tutorial Project Team Conducts workshops using spoken tutorials
07:42 Gives certificates to those who pass an online test
07:45 For more details, please write to contact@spoken-tutorial.org
07:51 Spoken Tutorial Project is a part of the Talk to a Teacher project
07:55 It is supported by the National Mission on Education through ICT,MHRD,Government of India
08:02 More information on this Mission is available at: [1]
08:07 This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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