Question

I’m trying to learn to use awk but it’s not behaving how I expect. Here’s my trouble:

$ echo "Hello brave new world" | awk "{print $1}"
Hello brave new world

I expected to see “Hello”, as this is the first field. Why don’t the spaces count as field delimiters?

Answer 1

It’s because Bash is interpreting $1 as referring to the first shell argument, so it replaces it with its value. Since, in your case, that parameter is unset, $1 just gets replaced with the empty string; so your AWK program is actually just {print }, which prints the whole line.

To prevent Bash from doing this, wrap your AWK program in single-quotes instead of double-quotes:

echo "Hello brave new world" | awk '{print $1}'

or

echo 'Hello brave new world' | awk '{print $1}'