Get full workbook name and path

The CELL function can return various information about a worksheet. CELL can get things like address and filename, as well as detailed info about the formatting used in the cell. The type of information to be returned is specified by  the info_type argument. 

In this example, we want the path, name, and sheet for the current workbook. To get this information, the info_type argument is set to "reference" in a formula like this:

=CELL("filename",A1)

The second argument, reference, is optional and  can be any cell in the worksheet.  If reference is not supplied, CELL will return the name of the current "active sheet" which may or may not be the sheet where the formula exists, and might even be in a different workbook. To eliminate confusion, supply A1 for reference.

CELL will return the name in this format:

path[workbook.xlsx]sheetname

Note that you must save the worksheet in order to get the a result.