I've recently been uncovering the useful commandline tools that can be found natively in Windows, one of which was findstr (there is also a GUI interface available in SciTE4AutoIt3.) After coming across this little gem and implementing in >SciTE Jump, it felt only right that I should share this on the forums as a standalone UDF. Thanks  Function:  ; #FUNCTION# ====================================================================================================================
; Name ..........: _FindInFile
; Description ...: Search for a string within files located in a specific directory.
; Syntax ........: _FindInFile($sSearch, $sFilePath[, $sMask = '*'[, $fRecursive = True[, $fLiteral = Default[,
;                  $fCaseSensitive = Default[, $fDetail = Default]]]]])
; Parameters ....: $sSearch             - The keyword to search for.
;                  $sFilePath           - The folder location of where to search.
;                  $sMask               - [optional] A list of filetype extensions separated with ';' e.g. '*.au3;*.txt'. Default is all files.
;                  $fRecursive          - [optional] Search within subfolders. Default is True.
;                  $fLiteral            - [optional] Use the string as a literal search string. Default is False.
;                  $fCaseSensitive      - [optional] Use Search is case-sensitive searching. Default is False.
;                  $fDetail             - [optional] Show filenames only. Default is False.
; Return values .: Success - Returns a one-dimensional and is made up as follows:
;                            $aArray[0] = Number of rows
;                            $aArray[1] = 1st file
;                            $aArray[n] = nth file
;                  Failure - Returns an empty array and sets @error to non-zero
; Author ........: guinness
; Remarks .......: For more details: http://ss64.com/nt/findstr.html
; Example .......: Yes
; ===============================================================================================================================
Func _FindInFile($sSearch, $sFilePath, $sMask = '*', $fRecursive = True, $fLiteral = Default, $fCaseSensitive = Default, $fDetail = Default)
	Local $sCaseSensitive = $fCaseSensitive ? '' : '/i', $sDetail = $fDetail ? '/n' : '/m', $sRecursive = ($fRecursive Or $fRecursive = Default) ? '/s' : ''
	If $fLiteral Then
		$sSearch = ' /c:' & $sSearch
	EndIf
	If $sMask = Default Then
		$sMask = '*'
	EndIf
	$sFilePath = StringRegExpReplace($sFilePath, '[\\/]+$', '') & '\'
	Local Const $aMask = StringSplit($sMask, ';')
	Local $iPID = 0, $sOutput = ''
	For $i = 1 To $aMask[0]
		$iPID = Run(@ComSpec & ' /c ' & 'findstr ' & $sCaseSensitive & ' ' & $sDetail & ' ' & $sRecursive & ' "' & $sSearch & '" "' & $sFilePath & $aMask[$i] & '"', @SystemDir, @SW_HIDE, $STDOUT_CHILD)
		ProcessWaitClose($iPID)
		$sOutput &= StdoutRead($iPID)
	Next
	Return StringSplit(StringStripWS(StringStripCR($sOutput), BitOR($STR_STRIPLEADING, $STR_STRIPTRAILING)), @LF)
EndFunc   ;==>_FindInFileExample use of Function: #include <Array.au3>
#include <Constants.au3>
Example()
Func Example()
	Local $hTimer = TimerInit()
	Local $aArray = _FindInFile('findinfile', @ScriptDir, '*.au3;*.txt') ; Search for 'findinfile' within the @ScripDir and only in .au3 & .txt files.
	ConsoleWrite(Ceiling(TimerDiff($hTimer) / 1000) & ' second(s)' & @CRLF)
	_ArrayDisplay($aArray)
	$hTimer = TimerInit()
	$aArray = _FindInFile('autoit', @ScriptDir, '*.au3') ; Search for 'autoit' within the @ScripDir and only in .au3 files.
	ConsoleWrite(Ceiling(TimerDiff($hTimer) / 1000) & ' second(s)' & @CRLF)
	_ArrayDisplay($aArray)
EndFunc   ;==>Example