unix regex for adding contents in a file

Question

i have contents in a file

like

asdfb ... 1
adfsdf ... 2
sdfdf ..   3

I want to write a unix command that should be able to add 1 + 2 + 3 and give the result as 6

From what I am aware grep and awk would be handy, any pointers would help.

Answer 1

This might not exactly be what you're looking for, but I wrote a quick Ruby script to accomplish your goal:

#!/usr/bin/env ruby

total = 0
while gets
    total += $1.to_i if $_ =~ /([0-9]+)$/
end
puts total

Answer 2

An awk script is all you need for that, since it has grep facilities built in as part of the language.

Let's say your actual file consists of:

asdfb zz 1
adfsdf yyy 2
sdfdf xx   3

and you want to sum the third column. You can use:

echo 'asdfb zz 1
adfsdf yyy 2
sdfdf xx   3' | awk '
    BEGIN {s=0;}
          {s = s + $3;}
    END   {print s;}'

The BEGIN clause is run before processing any lines, the END clause after processing all lines.

The other clause happens for every line but you can add more clauses to change the behavior based on all sorts of things (grep-py things).

Answer 3

I believe the following is what you're looking for. It will sum up the last field in each record for the data that is read from stdin.

awk '{ sum += $NF } END { print sum }' < file.txt

Some things to note:

1. With awk you don't need to declare variables, they are willed into existence by assigning values to them.
2. The variable NF is the number of fields in the current record. By prepending it with a $ we are treating its value as a variable. At least this is how it appears to work anyway :)
3. The END { } block is only once all records have been processed by the other blocks.

Answer 4

Here's one in Perl.

$ cat foo.txt
asdfb ... 1
adfsdf ... 2
sdfdf ..   3

$ perl -a -n -E '$total += $F[2]; END { say $total }' foo
6

Golfed version:

perl -anE'END{say$n}$n+=$F[2]' foo
6