Add up a column of numbers at the Unix shell

Question

Given a list of files in files.txt, I can get a list of their sizes like this:

cat files.txt | xargs ls -l | cut -c 23-30

which pr

Answer 1

python3 -c"import os; print(sum(os.path.getsize(f) for f in open('files.txt').read().split()))"

Or if you just want to sum the numbers, pipe into:

python3 -c"import sys; print(sum(int(x) for x in sys.stdin))"