#include <File.au3>
For $i = 1 To 3
_FileWriteToLine('1.txt', $i, ' ', 1)
Next
_FileDeleteEmptyLines(@ScriptDir & "\1.txt")
Func _FileDeleteEmptyLines($sFile)
Local $sFileContent = StringRegExpReplace(FileRead($sFile), "(\r?\n){1,}", "\1")
Local $hFOpen = FileOpen($sFile, 2 + FileGetEncoding($sFile))
FileWrite($hFOpen, StringStripWS($sFileContent, 3))
FileClose($hFOpen)
EndFunc