title: Shell Linux : grep exact sentence with NULL character
body: <p>I have a file like</p>
  
  <pre><code>key\0value\n
  akey\0value\n
  key2\0value\n
  </code></pre>
  
  <p>I have to create a script that take as argument a word. I have to return every lines having a key exactly the same than the argument.</p>
  
  <p>I tried</p>
  
  <pre><code>grep -aF "$key\x0"
  </code></pre>
  
  <p>but grep seems to do not understand the \x0 (\0 same result). Futhermore, I have to check that the line begins with "$key\0"</p>
  
  <p>I only can use sed grep and tr and other no maching commands</p>