title: Show unique filename only on command grep result
body: <p>I'm trying to show only unique filenames when I <em>grep</em> a certain string. Currently I'm getting multiple results with the same filename if a certain string appear several times inside a file.</p>
  
  <p>for example:</p>
  
  <p>If I have a string "string12345" and it appears 3 times in several lines inside filename1.txt and appear 3 times in several lines inside filename2.txt as well when I use *grep 'string12345' <em>.txt</em> it shows 3 occurrences of filename1.txt and filename2.txt</p>
  
  <p>Now what I'm trying to achieve is to show only 1 occurrence of filename1.txt and filename2.txt. Thank you in advance.</p>