#include <MsgBoxConstants.au3> ; to declare the Constants of MsgBox
Local $sRegex = "(?m)OPTIONS=\"(?:(.*)(-u [a-z]+:[a-z]+))?(.*?)\""
Local $sString = "OPTIONS="-x -u wrong:wrong -c blah"" & @CRLF & _
"OPTIONS="-u wrong:wrong -x -c blah"" & @CRLF & _
"OPTIONS="-x -c blah -u wrong:wrong"" & @CRLF & _
"OPTIONS="-x -c blah""
Local $sSubst = "OPTIONS="\1 \3 -u ntpd:ntpd""
Local $sResult = StringRegExpReplace($sString, $sRegex, $sSubst)
MsgBox($MB_SYSTEMMODAL, "Result", $sResult)
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for AutoIt, please visit: https://www.autoitscript.com/autoit3/docs/functions/StringRegExp.htm