The backup destination folder is stored in the Backup.xml file. You can programmatically get this information using 4D XML commands. Below is an sample code that does this:

 `Method: CheckBackupDestinationFolder
 ` Description: It will check and return the backup destination folder.
C_TEXT(Path_Structure;$0)
C_TEXT(Path_Prefs;Path_Structure;Path_BackupXML)
C_TEXT($elementRef1;$elementRef2)
C_INTEGER($separator;$StrPtr)
C_INTEGER($myPlatform;$mySystem;$myMachine)

PLATFORM PROPERTIES($myPlatform;$mySystem;$myMachine)
If ($myPlatform=Windows ) ` check if platform is Windows or Mac
 $separator:=Ascii("\\")
Else
 $separator:=Ascii(":")
End if

Path_Structure:=Structure file ` get the pathname of Structure file.
$StrPtr:=Length(Path_Structure) ` get length of string
While (Path_Structure[[$StrPtr]]#Char($separator)) ` starting from the end of string, find first occurence of the separator
 $StrPtr:=$StrPtr-1
End while
$var1:=Substring(Path_Structure;1;$StrPtr) ` extract path to preferences
Path_Prefs:=$var1+"Preferences"
Path_BackupXML:=Path_Prefs+Char($separator)+"Backup"+Char($separator)+"Backup.xml" ` path to backup.xml file
$ref1:=DOM Parse XML source(Path_BackupXML)
$elementRef1:=DOM Find XML element($ref1;"/Preferences4D/Backup/Settings/General")
$elementRef2:=DOM Find XML element($elementRef1;"/General/DestinationFolder") ` find Destination folder element
DOM GET XML ELEMENT VALUE($elementRef2;value) ` get element value for destination folder
DOM CLOSE XML($ref1)

$0:=value ` return destination folder of backup.