There are two simple ways to solve this:
1) if it is correct that each map ends with the key word 'exit' and if this key word won't occur in other positions within a map, you may read the complete file content into a single string, then use the split method to turn the string into an array using 'exit' as the separator. With a For-Next-Loop you can check each array element for the searched string.
2) you may use a regex object to parse the file content - this would be more elegant and easier but requires a good understanding of regular expressions.
Here's a sample created with VBScript:
Dim objFSO, filepath, objInputFile, tmpStr, substrToFind, arrRecords, r
Const ForReading = 1
Set objFSO = CreateObject("Scripting.FileSystemObject")
filepath = "C:\Users\Desktop\New Text Document.txt"
substrToFind = "1/2/x29,1/3/x27"
Set objInputFile = objFSO.OpenTextFile(filepath, ForReading)
tmpStr = objInputFile.ReadAll()
If InStr(tmpStr, substrToFind) <= 0 Then
WScript.Echo "No matches"
Else
arrRecords = Split(tmpStr, "exit")
For r = LBound(arrRecords, 1) To UBound(arrRecords, 1)
If Instr(arrRecords(r), substrToFind) > 0 Then
MsgBox "'" & substrToFind & "' found in " & (r +1) & ". record"
End If
Next
MsgBox "No more matches found"
End If