Difference between revisions of "Linux-AWK/C2/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 is named after its authors, '''Aho, Weinberger''' and '''Kernighan'''.

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

| Now open the '''terminal''' by pressing  

'''CTRL + ALT''' and '''T''' keys simultaneosuly on your keyboard.

'''awk space''' (within single quote) (front slash) ‘'''/Pass '''(front slash)'''/'''(opening curly bracket) '''{print (closing curly bracket)}''' (after the  quotes) '''space awkdemo.txt'''  

| Press '''Enter'''

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

| We can also use '''regular expressions''' in '''awk'''

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

'''awk space '/M opening square bracket [ ei closing square bracket ]*ra */{ print}' space awkdemo.txt'''

| '''"*"''' 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  

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

|Let me clear the promt

| '''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.  

|come back to our terminal

| 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.

| 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.  

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

| We will see more about builtin variables later.

| 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'''   

| '''Press Enter.'''

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

| Records are '''integers''', hence we have written''' %d'''.  

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

| '''15s''' will reserve 15 spaces for '''Stream''' 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

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