Simple aggregation using linux scripting

Question

Let's say I have a text file with lines like these:

foo 10
bar 15
bar 5
foo 30
...

What's the simplest way to generate the following output:

foo 40
bar 20

?

Answer 1

This will do:

awk '{arr[$1]+=$2;} END { for (i in arr) print i, arr[i]}'  file

For more information, read on Awk's associative arrays.