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

This Perl one-liner seems to do the job:

perl -nle '($k, $v) = split; $s{$k} += $v; END {$, = " "; foreach $k (sort keys %s) {print $k, $s{$k}}}' inputfile