title: grep excluding file name pattern
body: <p>I've read
  <a href="https://stackoverflow.com/questions/221921/use-grep-exclude-include-syntax-to-not-grep-through-certain-files">Use grep --exclude/--include syntax to not grep through certain files</a><br>
  but in my CentOS6.4, when I do  </p>
  
  <pre><code>grep --exclude=*.cmd ckim * -r
  </code></pre>
  
  <p>I see lots of grepped lines from *.cmd files.<br>
  so it seems the exclude option is not working for me.<br>
  What is wrong?<br>
  of course I can do things like  </p>
  
  <pre><code>grep ckim \`find . -name \*.c -print\`
  </code></pre>
  
  <p>but I want to know why the grep doesn't work.</p>