perl <br>
-i    #edit in place
.bak  #but make a new file
-p    # read every line from default arg
e     # excecute code from command line
'     #code for the default while loop
$_    # default variable, each line of file
.     # and
=     # equal to
"     #start printing this literally
\n    #new line
"     #finish literal printing
'     # end/start next loop