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;*************************************************************************
; Script Name: Find-_AC-Files
; Author: green78
; Date: 31/07/2007
; Description: Find and rename files with _AC in directory
;*************************************************************************


;Script Options
If
 Not @LOGONMODE
    Break On
Else
    Break Off
EndIf
Dim $RC
$RC = SetOption("Explicit", "On")
$RC = SetOption("NoMacrosInStrings", "On")
$RC = SetOption("NoVarsInStrings", "On")
If @SCRIPTEXE = "KIX32.EXE"
    $RC = SetOption("WrapAtEOL", "On")
EndIf

;Declare variables
Dim
 
$arrFiles, $strFile
Dim $strPath
Dim $strPrefix, $intPrefixLength

;Initialize variables
$strPath = "C:\Test\Test\"
$strPrefix = "BG_STAT_"
$intPrefixLength = Len($strPrefix)

;Code
$arrFiles = DirPlus($strPath,"/M _AC")
For Each $strFile in $arrFiles
    ;$strFile.Name ?
    ;$strFile.Path ?
    ;$strFile.ParentFolder ?
    If Not Left($strFile.Name,$intPrefixLength) = $strPrefix
        $strFile.Move($strFile.ParentFolder + "\" + $strPrefix + $strFile.Name)
   
EndIf
   
Next

;UDF Section
;Copy the DirPlus UDF here