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

cat files.txt | awk '{ total += $1} END {print total}'

You can use the awk to do the same it even skips the non integers

$ cat files.txt
1
2.3
3.4
ew
1

$ cat files.txt | awk '{ total += $1} END {print total}'
7.7

or you can use ls command and calculate human readable output

$ ls -l | awk '{ sum += $5} END  {hum[1024^3]="Gb"; hum[1024^2]="Mb"; hum[1024]="Kb"; for (x=1024^3; x>=1024; x/=1024) { if (sum>=x) { printf "%.2f %s\n",sum/x,hum[x]; break; } } if (sum<1024) print "1kb"; }'
15.69 Mb

$ ls -l *.txt | awk '{ sum += $5} END  {hum[1024^3]="Gb"; hum[1024^2]="Mb"; hum[1024]="Kb"; for (x=1024^3; x>=1024; x/=1024) { if (sum>=x) { printf "%.2f %s\n",sum/x,hum[x]; break; } } if (sum<1024) print "1kb"; }'
2.10 Mb