Linux-AWK/C2/Basics-of-awk/English - Revision history

Nancyvarkey: Nancyvarkey moved page Linux/C3/Basics-of-awk/English to Linux-AWK/C2/Basics-of-awk/English without leaving a redirect: New series

2018-03-22T11:02:39Z

Nancyvarkey moved page Linux/C3/Basics-of-awk/English to Linux-AWK/C2/Basics-of-awk/English without leaving a redirect: New series

Nancyvarkey at 11:02, 16 December 2013

2013-12-16T11:02:49Z

Nancyvarkey at 10:47, 16 December 2013

2013-12-16T10:47:07Z

Show changes

Ashwini at 10:24, 14 December 2013

2013-12-14T10:24:00Z

Ashwini at 10:22, 14 December 2013

2013-12-14T10:22:18Z

Ashwini at 10:20, 14 December 2013

2013-12-14T10:20:27Z

Ashwini: Created page with ''''Title of script''': The Awk tool Part 1 '''Author: Sachin Patil''' '''Keywords: Selection criteria, action, formatted printing, fields, Regular expressions, Variables''' …'

2013-07-01T09:59:56Z

Created page with ''''Title of script''': The Awk tool Part 1 '''Author: Sachin Patil''' '''Keywords: Selection criteria, action, formatted printing, fields, Regular expressions, Variables''' …'

New page

'''Title of script''': The Awk tool Part 1

'''Author: Sachin Patil'''

'''Keywords: Selection criteria, action, formatted printing, fields, Regular expressions, Variables'''

{| style="border-spacing:0;"
| style="border:1pt solid #000000;padding:0.097cm;"| <center>'''Visual Cue'''</center>
| style="border:1pt solid #000000;padding:0.097cm;"| <center>'''Narration'''</center>

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 1
| style="border:1pt solid #000000;padding:0.097cm;"| Welcome to this spoken tutorial on the '''awk''' command.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 2

Learning Objective
| style="border:1pt solid #000000;padding:0.176cm;"| In this tutorial we will learn,

awk command.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 3

System requirement
| style="border:1pt solid #000000;padding:0.176cm;"| To record this tutorial, I am using

Ubuntu Linux 12.04 OS

GNU BASH v. 4.2.24(1)

Please note, GNU bash version 4 or above is recommended to practice this tutorial.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 4

Introduction
| style="border:1pt solid #000000;padding:0.097cm;"| The''' awk''' command is a very powerful text manipulation tool of Linux.

It is named after its authors, Aho, Weinberger and Kernighan.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Continue Slide

| style="border:1pt solid #000000;padding:0.097cm;"| It can perform several functions.

It operates at the field level of a record.

So, it can easily access and edit the individual fields of the record.

|-
| style="border:1pt solid #000000;padding:0.097cm;"|
| style="border:1pt solid #000000;padding:0.097cm;"| Let us see some examples.

For demonstration purpose we use the''' awkdemo.txt '''file.

Let us see the contents of '''awkdemo.txt'''.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| '''awkdemo.txt'''
| style="border:1pt solid #000000;padding:0.176cm;"| This is the content of '''awkdemo.txt''' file.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Open the terminal

'''ctrl+alt+t'''

type:
| style="border:1pt solid #000000;padding:0.097cm;"| Now open the terminal by pressing '''ctrl+alt+t'''

|-
| style="border:1pt solid #000000;padding:0.097cm;"| type:

"awk '/Pass/ {print}' awkdemo.txt<nowiki>" [</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Now type:

'''awk''' space (opening single quote) (front slash) ‘'''/Pass '''(front slash)'''/'''(in curly brace) '''{print}''' (closing single quote) space '''awkdemo.txt'''

Here '''Pass''' is the selection criterion.

All the lines of the '''awkdemo''' where '''Pass''' occurs are printed.

The action here is print.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Type

"awk '/M<nowiki>[</nowiki>ei]*ra<nowiki>*/ {</nowiki>print}' awkdemo.txt<nowiki>" [</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| We can also use regular expressions in awk

Say we want to print records of students with name '''Mira.'''

We would type:

'''awk''' space ''''/M<nowiki>[</nowiki>ei]*ra<nowiki>*/{</nowiki>print}'''' space '''awkdemo.txt'''

Press '''Enter.'''

<nowiki>* </nowiki>will give one or more occurrences of previous character.

Thus entries with more than one occurrence for i, e and a will be listed

For ex. Meera

Mira

Meeraa

|-
| style="border:1pt solid #000000;padding:0.097cm;"|
| style="border:1pt solid #000000;padding:0.097cm;"| '''awk''' supports the extended regular expressions (ERE).

Which means we can match multiple patterns separated by a PIPE.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Type

"awk '/civil|electrical/ {print}' awkdemo<nowiki>" [</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Type at the terminal:

'''awk''' space (in single quotes)(front slash) ‘'''/civil''' (vertical bar)'''|electrical '''(front slash)'''/{print}'''' '''awkdemo.txt'''

'''Press Enter.'''

Now entries for both '''civil''' and '''electrical''' are shown.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display slide 7

| style="border:1pt solid #000000;padding:0.097cm;"| Lets go back to the slides.

Awk has some special parameters to identify individual fields of a line.

$1(Dollar 1) would indicate the first field.

Similarly we can have $2, $3 and so on for respective fields.

$0 represents the entire line.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Switch to the terminal

Type: cat awkdemo.txt
| style="border:1pt solid #000000;padding:0.176cm;"| Note that each word is separated by '''PIPE''' in the file '''awkdemo.txt.'''

In this case '''PIPE '''is called a '''delimiter.'''

A delimiter separates words from each other.

A delimiter can also be a single '''whitespace. '''

To specify a delimiter we have to give '''-F '''flag followed by a delimiter.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Type

“awk -F "|" '/civil|electrical/ {print $0}' awkdemo<nowiki> ” [</nowiki>enter]

| style="border:1pt solid #000000;padding:0.176cm;"| Lets go back to the terminal.

So we can write the last command as:

'''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 '''now outside the quotes space''' awkdemo.txt'''

This print the entire line since we have used '''$0.'''

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Type

“awk -F"|" '/Pass/ {print $2, $3}' awkdemo<nowiki>” [</nowiki>enter]
| style="border:1pt solid #000000;padding:0.097cm;"| Notice that, names and stream of students are the second and third fields.

Say we only want to print two fields.

We will replace '''$0''' with '''$2,$3''' in the above command.

Let’s try.

press '''Enter '''

|-
| style="border:1pt solid #000000;padding:0.097cm;"|
| style="border:1pt solid #000000;padding:0.097cm;"| Though it gives the right result the display is all jagged and unformatted.

|-
| style="border:1pt solid #000000;padding:0.176cm;"| “awk -F"|" '/Pass/ {printf "%4d %-25s %-15s \n",

NR,$2,$3 }' awkdemo” <nowiki>[</nowiki>enter]

| style="border:1pt solid #000000;padding:0.176cm;"| We can provide formatted output by using the C style '''printf '''statement.

We can also provide a serial number by using a builtin variable NR.

We will see more about builtin variables later.

We would write:

'''awk''' space '''-F”|”''' space ''''/Pass/{printf “%4d %-25s %-15s \n”,''' '''NR,$2,$3 }'''' space '''awkdemo.txt'''

'''Press Enter.'''

Here the NR stands for number of records.

records are integers, hence we have written %d.

Name and stream are strings. So we have used %s.

Here 25s will reserve 25 spaces for Name field.

15s will reserve for Stream field.

The minus sign is used to left justify the output.

|-
| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 11

Acknowledgement Slide

| style="border:1pt solid #000000;padding:0.097cm;"| Watch the video available at the link shown below

It summarises the Spoken Tutorial project

If you do not have good bandwidth, you can download and watch it

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 12

Spoken Tutorial Workshops

| style="border:1pt solid #000000;padding:0.176cm;"| The Spoken Tutorial Project Team

Conducts workshops using spoken tutorials

Gives certificates to those who pass an online test

For more details, please write to

contact@spoken-tutorial.org

|-
| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 13

Acknowledgement

| style="border:1pt solid #000000;padding:0.176cm;"| Spoken Tutorial Project is a part of the Talk to a Teacher project

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

More information on this Mission is available at: [http://spoken-tutorial.org/ http][http://spoken-tutorial.org/ ://][http://spoken-tutorial.org/ spoken][http://spoken-tutorial.org/ -][http://spoken-tutorial.org/ tutorial][http://spoken-tutorial.org/ .][http://spoken-tutorial.org/ org]\NMEICT-Intro

|-
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.176cm;"| No Last Slide for tutorials created at IITB

Display the previous slide only and narrate this line.
| style="border-top:none;border-bottom:1pt solid #000000;border-left:1pt solid #000000;border-right:1pt solid #000000;padding:0.176cm;"| The script has been contributed by Sachin Patil.

This is Ashwini Patil from IIT Bombay signning off. Thank you for joining.

|}

@@ Line 249: / Line 249: @@
-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'''.
@@ Line 265: / Line 265: @@
-Here the NR stands for number of records.
+Here the '''NR''' stands for number of records.
-records are integers, hence we have written %d.
+Records are '''integers''', hence we have written''' %d'''.
-Name and stream are strings. So we have used %s.
+'''Name''' and '''Stream''' are '''strings'''. So we have used '''%s'''.
-Here 25s will reserve 25 spaces for Name field.
+Here '''25s''' will reserve 25 spaces for '''Name''' field.
-s will reserve for Stream field.
+'''15s''' will reserve for '''Stream''' field.
-The minus sign is used to left justify the output.
+The '''minus sign''' is used to left justify the output.
-Let us move back to our slides.
+|-
-|-
-| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 8
+Let us move back to our slides.
-|style="border:1pt solid #000000;padding:0.176cm;"| Let us summarize.
+Let us summarize.
 In this tutorial we learnt

@@ Line 300: / Line 300: @@
-Let us summarize.
+|style="border:1pt solid #000000;padding:0.176cm;"| Let us summarize.
-|In this tutorial we learnt
+In this tutorial we learnt
 To print using awk
@@ Line 318: / Line 318: @@
 | style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 9
- As an assignment
+| style="border:1pt solid #000000;padding:0.176cm;" | As an assignment
-|Display roll no., stream and marks of Ankti Saraf
+Display roll no., stream and marks of Ankti Saraf

@@ Line 299: / Line 299: @@
 | style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 8
-In this tutorial we learnt
+Let us summarize.
 To print using awk
@@ Line 317: / Line 318: @@
 | style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 9
-| As an assignment
+ As an assignment
-Display roll no., stream and marks of Ankti Saraf
+|Display roll no., stream and marks of Ankti Saraf
 |-
-| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 11
+| style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 10
 Acknowledgement Slide
@@ Line 336: / Line 337: @@
 |-
-| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 12
+| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 11
 Spoken Tutorial Workshops
@@ Line 353: / Line 354: @@
 |-
-| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 13
+| style="border:1pt solid #000000;padding:0.176cm;"| Display Slide 12
 Acknowledgement

← Older revision	Revision as of 11:02, 22 March 2018
(No difference)

@@ Line 1: / Line 1: @@
-'''Title of script''': The Awk tool Part 1
+'''Title of script''': The Awk Command
-'''Author: Sachin Patil'''
+'''Author: Sachin Patil and Anirban'''
 '''Keywords: Selection criteria, action, formatted printing, fields, Regular expressions, Variables'''
@@ Line 13: / Line 13: @@
 |-
 | style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 1
-| style="border:1pt solid #000000;padding:0.097cm;"| Welcome to this spoken tutorial on the '''awk''' command.
+| style="border:1pt solid #000000;padding:0.097cm;"| Welcome to the spoken tutorial on the '''awk''' command.
 |-
@@ Line 22: / Line 22: @@
 awk command.
 |-
@@ Line 31: / Line 33: @@
 Ubuntu Linux 12.04 OS
-GNU BASH v. 4.2.24(1)
+GNU BASH v. 4.2.24
 Please note, GNU bash version 4 or above is recommended to practice this tutorial.
@@ Line 37: / Line 39: @@
 |-
 | style="border:1pt solid #000000;padding:0.097cm;"| Display Slide 4
 Introduction
-| style="border:1pt solid #000000;padding:0.097cm;"| The''' awk''' command is a very powerful text manipulation tool of Linux.
+| style="border:1pt solid #000000;padding:0.097cm;"| The''' awk''' command is a very powerful text manipulation tool.
 It is named after its authors, Aho, Weinberger and Kernighan.
@@ Line 60: / Line 64: @@
 For demonstration purpose we use the''' awkdemo.txt '''file.
-Let us see the contents of '''awkdemo.txt'''.
+Let us see the contents of '''awkdemo.txt''' file.
-−
-−
-−
 |-
@@ Line 70: / Line 71: @@
 |-
-| style="border:1pt solid #000000;padding:0.176cm;"| Open the terminal
+| style="border:1pt solid #000000;padding:0.176cm;"| Now open the terminal
-'''ctrl+alt+t'''
+'''CTRL + ALT and T keys''' simultaneosuly on your keyboard.
 type:
-| style="border:1pt solid #000000;padding:0.097cm;"| Now open the terminal by pressing '''ctrl+alt+t'''
+| style="border:1pt solid #000000;padding:0.097cm;"| Now open the terminal by pressing '''CTRL + ALT and T keys''' simultaneosuly on your keyboard.
 |-
@@ Line 83: / Line 84: @@
 "awk '/Pass/ {print}' awkdemo.txt<nowiki>" [</nowiki>enter]
-| style="border:1pt solid #000000;padding:0.097cm;"| Now type:
+| style="border:1pt solid #000000;padding:0.097cm;"| Let us see how to print using awk command.
 Here '''Pass''' is the selection criterion.
@@ Line 109: / Line 114: @@
-'''awk''' space ''''/M<nowiki>[</nowiki>ei]*ra<nowiki>*/{</nowiki>print}'''' space '''awkdemo.txt'''
+'''awk''' space ''''/M<nowiki>opening square bracket [</nowiki>ei closing square bracket ]*ra<nowiki>*/{</nowiki>print}'''' space '''awkdemo.txt'''
@@ Line 126: / Line 131: @@
 Meeraa
@@ Line 140: / Line 143: @@
 "awk '/civil|electrical/ {print}' awkdemo<nowiki>" [</nowiki>enter]
-| style="border:1pt solid #000000;padding:0.097cm;"| Type at the terminal:
+| style="border:1pt solid #000000;padding:0.097cm;"| Now type:
@@ Line 156: / Line 159: @@
-| style="border:1pt solid #000000;padding:0.097cm;"| Lets go back to the slides.
+| style="border:1pt solid #000000;padding:0.097cm;"| Let us go back to our slides.
@@ Line 187: / Line 190: @@
-To specify a delimiter we have to give '''-F '''flag followed by a delimiter.
+To specify a delimiter we have to give '''- capital F '''flag followed by a delimiter.
@@ Line 216: / Line 219: @@
 Within curly braces''' print''' space '''dollar0 '''now outside the quotes space''' awkdemo.txt'''
 This print the entire line since we have used '''$0.'''
@@ Line 232: / Line 236: @@
-Let’s try.
+press '''Enter '''
+Only two fields are shown.
-press '''Enter '''
 |-
@@ Line 260: / Line 263: @@
-We would write:
+Now type:
 '''awk''' space '''-F”|”''' space ''''/Pass/{printf “%4d %-25s %-15s \n”,''' '''NR,$2,$3 }'''' space '''awkdemo.txt'''
@@ Line 266: / Line 269: @@
 '''Press Enter.'''
@@ Line 285: / Line 290: @@
 The minus sign is used to left justify the output.