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

| Welcome to the spoken tutorial on the '''awk''' command.

|  In this tutorial we will learn, '''awk command.'''

| To record this tutorial, I am using

| It operates at the field level of a record.  

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

| Now open the '''terminal''' window

| Press '''Enter'''

|Here '''Pass''' is the selection criteria.  

| The action here is print.  

| 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 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'''

| '''"*(asterisk)"'''  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 example  

| Mira (with 'M'  'I'  'R'  'A')

| Meera(with 'M'  'E'  'E'  'R'  'A')

| *Meeraa(with M E E R A A )

| '''awk''' supports the '''extended regular expressions (ERE)'''.

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

|Let me clear the promt

|Now type:

| '''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'''

| Now entries for both '''civil''' and '''electrical''' are given.

| Parameters '''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.  

|come back to our terminal

| 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 '''- capital F '''flag followed by a '''delimiter'''.

| Let us see  

| 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'''

| Press '''Enter'''

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

| 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 and$3''' in the above command.

| Press '''Enter '''

| Though it gives the right result, the display is all jagged and unformatted.  

| 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'''  

| Here the '''NR''' stands for number of records.  

| Here '''25s''' will reserve 25 spaces for '''Name''' field.

| In this tutorial we learnt To print using '''awk'''

| Regular expression in '''awk'''. To list the enteries for a paritcular stream

| To list only the second and the third fileds

| To display a formatted output

| As an assignment  

| Display roll no., stream and marks of Ankti Saraf

|  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

|The Spoken Tutorial Project Team Conducts workshops using spoken tutorials

| Gives certificates to those who pass an online test

|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://spokentutorial.org\NMEICT-Intro]

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