title: List just the names of files that contain a string in Linux
body: <p>I want to list just the names of files that contain a string using Linux commands. </p>
  
  <p>When using egrep, all the instances of the string are shown, which could be multiples times.</p>
  
  <p><strong>For example:</strong></p>
  
  <pre><code>egrep disco music_file*.txt
  </code></pre>
  
  <p><strong>Might show;</strong></p>
  
  <pre><code>music_file1.txt: blah blah blah disco stuff
  
  music_file1.txt: disco blah blah blah
  
  music_file1.txt: I like to listen to italodisco
  
  music_file2.txt: I like to party to disco
  
  music_file3.txt: Does your dog like disco?
  </code></pre>
  
  <p><strong>Whereas all I want is :</strong></p>
  
  <pre><code>music_file1.txt
  
  music_file2.txt
  
  music_file3.txt
  </code></pre>
  
  <p><strong>Question:</strong> <em>How can I just show one instance of each file name when searching for a string in Linux?</em></p>