title: Debugging bitbake pkg_postinst_${PN}: Append to config-file installed by other recipe
body: <p>I'm writing am openembedded/bitbake recipe for openembedded-classic. My recipe RDEPENDS on keyutils, and everything seems to work, except one thing:
  I want to append a single line to the /etc/request-key.conf file installed by the keyutils package. So I added the following to my recipe:</p>
  
  <pre><code>pkg_postinst_${PN} () {
    echo 'create ... more stuff ..' &gt;&gt; ${sysconfdir}/request-key.conf
  }
  </code></pre>
  
  <p>However, the intended added line is missing in my resulting image.
  My recipe inherits <code>update-rc.d</code> if that makes any difference.</p>
  
  <p>My main question is: How do i debug this? Currently I am constructing an entire rootfs image, and then poke-around in that to see, if the changes show up. Surely there is a better way?</p>
  
  <p><strong>UPDATE:</strong>
  Changed recipe to:</p>
  
  <pre><code>pkg_postinst_${PN} () {
    echo 'create ... more stuff ...' &gt;&gt; ${D}${sysconfdir}/request-key.conf
  }
  </code></pre>
  
  <p>But still no luck.</p>