Comment by pjungwir | Hacker News Reader

Comment by pjungwir | Hacker News Reader

Just stumbled on this one recently, I forget where:

    foo | awk '{ print $NF }'

That prints the last column. $NF = number of fields. I use it a lot like this:

    git status | grep deleted: | awk '{ print $NF }' | xargs foo

I actually just realized, though, that I don't understand why this works. It seems like it should be '{ print ${$NF} }' or something, and the command as-given should just print "3" or "6" or whatever. I'm not an awk expert, so I'd love to understand what's going on here.

Bare NF is number of fields, so the $ must be pulling the value first. Also, awk is 1-based, not 0, so you get the last field :)

    cat > asdf.txt <<EOF
    a b
    c d e
    f g h i j
    EOF
    cat asdf.txt | awk '{print $1}'
    cat asdf.txt | awk '{print $2}'
    cat asdf.txt | awk '{print $(3-1)}'
    cat asdf.txt | awk '{print NF}'
    cat asdf.txt | awk '{print $NF}'

This always bugs me:

    git status | grep deleted: | awk '{ print $NF }' | xargs foo

Instead of using both grep and awk just use awk:

    git status | awk '/deleted:/ {print $NF}' | xargs foo

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