GROUP BY/SUM from shell

Question

I have a large file containing data like this:

a 23
b 8
a 22
b 1

I want to be able to get this:

a 45
b 9

Answer 1

Edit: The modern (GNU/Linux) solution, as mentioned in comments years ago ;-) .

awk '{
    arr[$1]+=$2
   }
   END {
     for (key in arr) printf("%s\t%s\n", key, arr[key])
   }' file \
   | sort -k1,1

The originally posted solution, based on old Unix sort options:

awk '{
    arr[$1]+=$2
   }
   END {
     for (key in arr) printf("%s\t%s\n", key, arr[key])
   }' file \
   | sort +0n -1

I hope this helps.