title: What are $0 and $1 (dollar sign 0 and 1) in an awk script?
body: <p>For example in <a href="https://developer.apple.com/library/mac/#documentation/opensource/Conceptual/ShellScripting/Howawk-ward/Howawk-ward.html" rel="nofollow noreferrer">this <code>awk</code></a> tutorial there are three examples:</p>
  <ol>
  <li><code>tolower($1) ~ /mary/ { print &quot;CI Record: &quot; $0; }</code></li>
  <li><code>$0 !~ /Mary/ { print &quot;Not Mary: &quot; $0; }</code></li>
  <li><code>$1 == &quot;Mary&quot; { print &quot;Mary Record: &quot; $0; }</code></li>
  </ol>