title: How to count number of non empty lines in a file using sed?
body: <p>how to find how many lines I have in file by sed
  (need to ignore spaces and empty lines)</p>
  
  <p>for example</p>
  
  <p>if I have file with 139 lines (line can include only one character)
  then sed should return 139</p>
  
  <p>lidia</p>