Question

My command looks like this:

cut -f 1 dummy_FILE | sort | uniq -c | awk ‘{print $2}’ | for i in $(cat -); do grep -w $i dummy_FILE |
awk -v VAR=”$i” ‘{distance+=$3-$2} END {print VAR, distance}’; done

cat dummy_FILE
Red   13    14
Red   39    46
Blue   45    23
Blue   34    27
Green   31    73

I want to:
For every word in $1 dummy_FILE (Red, Blue, Green) – Calculate sum of differences between $3 and $2.

To get the output like this:

Red 8  
Blue -29  
Green 42 

My questions are:

1. Is it possible to replace cut -f 1 dummy_FILE | sort | uniq -c | awk '{print $2}'?
   I am using sort | uniq -c to extract every word from the dataset – is it possible to do it with awk?

2. How can I overcome useless cat in for i in $(cat -)?

3. grep -w $i dummy_FILE works fine, but I want to replace it with awk (should I?); If so how can I do this?
   When I am trying to awk -v VAR="$i" '/^VAR/ '{distance+=$3-$2} END {print VAR, distance}' I am getting "fatal: division by zero attempted".

Answer 1

Here’s one way using awk:

awk '{ a[$1]=a[$1] + $3 - $2 } END { for(i in a) print i, a[i] }' dummy

Results:

Red 8
Blue -29
Green 42

If you require sorted output, you could simply pipe into sort like arutaku suggests:

awk '{ a[$1]=a[$1] + $3 - $2 } END { for(i in a) print i, a[i] }' dummy | sort

You can however, print into sort (within the awk statement), like this:

awk '{ a[$1]=a[$1] + $3 - $2 } END { for(i in a) print i, a[i] | "sort" }' dummy