title: Escape sequence for awk coprocess containing bracket
body: <p>I'm attempting to execute diff from within a awk script thusly...</p>
  
  <pre><code>cmd="diff &lt;(echo \""bServers[nonServers]"\") &lt;(echo \""primeReference"\")"
  print cmd
  while (( cmd | getline result) &gt; 0 ) {print result}
  close(cmd)}
  </code></pre>
  
  <p>...where bServers[nonServers] and primeReference evaluate as vanilla strings with no special characters. Hence the "print cmd" produces...</p>
  
  <pre><code>diff &lt;(echo "
  &gt; /var/tmp/text1.txt 818e9c0fc3dd92e86c80704419b1cc0d") &lt;(echo "
  &gt; /var/tmp/text2.txt 00efcc10b376dbdd6d0972635eb650c4")
  2c2
  &lt; /var/tmp/text1.txt 818e9c0fc3dd92e86c80704419b1cc0d
  ---
  &gt; /var/tmp/text2.txt 00efcc10b376dbdd6d0972635eb650c4
  </code></pre>
  
  <p>...which works fine when cut and paste to the command line. but when run as part of the Awk command returns...</p>
  
  <pre><code>/var/tmp/text2.txt 818e9c0fc3dd92e86c80704419b1cc0d")
  sh: -c: line 0: syntax error near unexpected token `('
  'h: -c: line 0: `diff &lt;(echo "
  </code></pre>
  
  <p>A single escaping backslash before the open bracket produces...</p>
  
  <pre><code>awk: warning: escape sequence `\(' treated as plain `('
  </code></pre>
  
  <p>Double produces...</p>
  
  <pre><code>sh: (echo: No such file or directory
  </code></pre>
  
  <p>Triple backslashes produces...</p>
  
  <pre><code>awk: warning: escape sequence `\(' treated as plain `('
  ...
  sh: (echo: No such file or directory
  </code></pre>
  
  <p>...and four backslashes (for laughs) just repeats the cycle with an ever increasing number of backslashes ad infinitum.</p>
  
  <p>The shell is GNU bash version 4.1.2(1)-release, awk is GNU Awk 3.1.7 and OS is CentOS release 6.2 (Final).</p>
  
  <p>I've tried variations with single quotes to no avail as well, does anyone have any idea where my shell-escape-foo is lacking?</p>