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.

Answer 2

The whole ls -l and then cut is rather convoluted when you have stat. It is also vulnerable to the exact format of ls -l (it didn't work until I changed the column numbers for cut)

Also, fixed the useless use of cat.

<files.txt  xargs stat -c %s | paste -sd+ - | bc

Answer 3

sizes=( $(cat files.txt | xargs ls -l | cut -c 23-30) )
total=$(( $(IFS="+"; echo "${sizes[*]}") ))

Or you could just sum them as you read the sizes

declare -i total=0
while read x; total+=x; done < <( cat files.txt | xargs ls -l | cut -c 23-30 )

If you don't care about bite sizes and blocks is OK, then just

declare -i total=0
while read s junk; total+=s; done < <( cat files.txt | xargs ls -s )

Answer 4

Pipe to gawk:

 cat files.txt | xargs ls -l | cut -c 23-30 | gawk 'BEGIN { sum = 0 } // { sum = sum + $0 } END { print sum }'

Answer 5

Here's mine

cat files.txt | xargs ls -l | cut -c 23-30 | sed -e :a -e '$!N;s/\n/+/;ta' | bc

Answer 6

You can use the following script if you just want to use shell scripting without awk or other interpreters:

#!/bin/bash

total=0

for number in `cat files.txt | xargs ls -l | cut -c 23-30`; do
   let total=$total+$number
done

echo $total