title: use ls command to find some *.app files on macos
body: <p>There are some .app files in the folder, such as </p>
  
  <pre><code>   folder_A/1.app
             /2.app
             /subF/3.app
             /3.txt
  </code></pre>
  
  <p>Then i want to use ls command to check if there are any .app files under folder_A, i can use <code>ls -R folder_A</code>  to list all the files under "folder_A" and sub folder "subF", but on Macos, the app file is also considered as an directory that ls will list all the files contained in 1.app,2.app and so on.</p>
  
  <p>For example, 1.app contains some .png,.txt; then <code>ls -R folder_A</code> will return all the png and txt files, not the 1.app itself. But i want to list all the app files under folder_A and its sub folder without list all the files included in .app.</p>