title: gawk match function parameter as regular expression
body: <p>I encounter error when I use gawk. Below is the my script and example file
  Can you guys help me? I think regex is right but there is an error when it passed to the match function. I try various approach such as give \ to special character of regex or double .</p>
  <p>$ cat script.sh</p>
  <pre><code>#!/bin/bash
  gawk '
  BEGINFILE{
          while( getline &lt; FILENAME &gt; 0 ){
                  print match($0, /[0-9]+\.[0-9]+(?= ops/s)/)
                  print $0
          }
  }
  ' ./file
  </code></pre>
  <p>$ cat file</p>
  <pre><code>123.456: IO Summary: 123456 ops 1234.567 ops/s 100/100 rd/wr   1.0mb/s 1.111ms/op
  </code></pre>
  <p>$ sh script.sh</p>
  <pre><code>gawk: cmd. line:4: error: Unmatched ( or \(: /[0-9]+\.[0-9]+(?= ops/
  </code></pre>