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

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.