If you consider the use of dc/bc as in the other solutions to be cheating, you can use unary-encoded integers... alias sum='xargs -I{} sh -c "head -c {} < /

If you consider the use of dc/bc as in the other solutions to be cheating, you can use unary-encoded integers... alias sum='xargs -I{} sh -c "head -c {} < /dev/zero" | wc -c'