title: Ubuntu linux command extract substring inside
body: <p>I have a txt file on ubuntu containing </p>
  
  <p>-rw-r--r-- 1 ftp ftp              0 Feb 26 11:37 6.txt <br>
  -rw-r--r-- 1 ftp ftp              0 Feb 26 11:37 7.txt <br>
  -rw-r--r-- 1 ftp ftp              0 Feb 26 11:37 8.txt <br></p>
  
  <p>can I just want to retrieve the file name like</p>
  
  <p>6.txt <br>
  7.txt <br>
  8.txt <br></p>
  
  <p>to another text file</p>