title: how to create blank lines in a linux file
body: <p>This is my file, I want to create a blank lines after each character existing line, i know how to delete blank lines in a linux files by using sed /^$/ filename, i have  a big file like this  and i don't want to create a blank line manually </p>
  
  <pre><code>$ cat filename
  Perl 5.18 is not binary compatible with Perl 5.16 and earlier
  releases. In particular, do not attempt to use extensions or PPM
  packages built for ActivePerl 1600 and older series builds with
  ActivePerl 1800 series builds and vice versa. Please check
  "Incompatible Changes" in perl5180delta for known source level
  incompatibilities between the Perl 5.18 releases and the earlier
  release series
  </code></pre>
  
  <p><strong>Expected Output:</strong></p>
  
  <pre><code>Perl 5.18 is not binary compatible with Perl 5.16 and earlier releases. In particular, do not attempt to 
  
  use extensions or PPM packages built for ActivePerl 1600 and older series builds with ActivePerl 1800 
  
  series builds and vice versa. Please check "Incompatible Changes" in perl5180delta for known source 
  
  level incompatibilities between the Perl 5.18 releases and the earlier release series
  </code></pre>