title: What does %var:~0,4% and %var:.=% mean in batch file?
body: <p>Here is my sample batch file code and I really don't know what it does.</p>
  
  <pre><code>set TEMPRPSW=%RPSW_VERSION%
  set RELVER=%TEMPRPSW:~0,4%
  set RELVER=%RELVER:.=%
  if %RELVER% GEQ 30 goto :eof
  </code></pre>
  
  <p>Please give me a working sample.</p>