how to match two lines and subtract them [closed]

Answer 1

awk '{if(a[$2]){print $1-a[$2]}else{a[$2]=$1;}}' your_file

Answer 2

Code for GNU awk:

awk 'a[$2]?a[$2]-=$1:a[$2]+=$1 {next} END {for (i in a) print -a[i]}' file

Answer 3

You can do something like:

awk '{a[$2]?b[++i]=$1-a[$2]:a[$2]=$1}END{for(;x<length(b);) print b[++x]}' inputFile