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

if you don't have bc installed, try

echo $(( $(... | paste -sd+ -) ))

instead of

... | paste -sd+ - | bc

$( ) <-- return the value of executing the command

$(( 1+2 )) <-- return the evaluated results

echo <-- echo it to the screen