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

Instead of using cut to get the file size from output of ls -l, you can use directly:

$ cat files.txt | xargs ls -l | awk '{total += $5} END {print "Total:", total, "bytes"}'

Awk interprets "$5" as the fifth column. This is the column from ls -l that gives you the file size.