break on

dim $Out, $FileArray, $file
dim $outArray, $line
$Out = @scriptdir + "\result.txt"
$FileArray = @scriptdir + "\file1.txt",@scriptdir + "\file2.txt",@scriptdir + "\file3.txt"

for each $file in $FileArray
   if open(1,$file) = 0
      $line = readline(1)
      while @error = 0
         if ubound($outArray) < 0
            redim $outArray[0]
            $outArray[0] = $line
         else
            if ascan($outArray,$line) < 0
               redim preserve $outArray[ubound($outArray)+1]
               $outArray[ubound($outArray)] = $line
            endif
         endif
         $line = readline(1)
      loop
      $ = close(1)
   endif
next

if open(1,$Out,5) = 0
   for each $line in $outArray
      $ = writeline(1, $line + @crlf)
   next
   $ = close(1)
endif