請高手幫忙解釋下面代碼段中紅字部分參數或函數的意思￣！！

grazyghost

$FILE = " /tempfile.txt ";
$keyword = "" ;　


if ( open (FLIEHANDLE, "$FILE" == 1 )
{
    $, = "\n";
while ( defined ($_ = <FILE>; ) )
  {
      @fileds = split ( /[  \n ]/  );
...  ...
   
    if ($keyword = ~m/ usename: /)  
  
  }
}[/img]