Hello,

I am practising awk and decided to compare two columns and print the result of the comparison as third column

i/p data

Code:

c1,c2,c3
1,a,b
1,b,b

i am trying to compare the last two columns and if they match I am trying to print match else mismatch(Ideally i want that as a last column in the same file

Code:

#!/bin/bash
IFS="," while read -r $line
a=awk '{print $1, ($NF=$(NF-1))?"match":"mismatch"}'<filename.txt
awk -v var=$a '{BEGIN s=a}{print $0,s}
'

expected output

Code:

c1,c2,c3,c4
1,a,b,mismatch
1,b,b,match

but all I am getting is

Code:

c1,c2,c3
1,a,b
1,b,b

or if just say awk'{print $NF}
I am getting the output as

Code:

c1,c2,c3
1,a,b
1,b,b

same out put even if i use $(NF-1)

I also tried commenting the
awk -v var=$a '{BEGIN s=a}{print $0,s} line in my code and ran it

Code:

#!/bin/bash
IFS="," while read -r $line
awk '{print $1, ($NF=$(NF-1))?"match":"mismatch"}'<filename.txt
#awk -v var=$a '{BEGIN s=a}{print $0,s}
'

the output i get is

Code:

c1,c2,c3,match
1,a,b,match
1,b,b,match

But i Read $NF returns the last column and NF-1 returns the last but one column.

Please advice where my thinking is wrong.

Thanks.