title: Unix Remove all occurences of character and save
body: <p>How to remove all occurences of string "???" of a file and save it?</p>
  
  <p>My approach so far:</p>
  
  <pre><code>cat file.txt | sed -ie '/s/???//' file.txt
  </code></pre>
  
  <p>However I get the following error:</p>
  
  <pre><code>sed: -e expression #1, char 4: unknown command: `?'
  </code></pre>