How to safely append a file name to a Windows folder path argument?

Question

Suppose I have a batch script that expects a folder path in argument %1. I want to append a file name to the path and use that in a command. Is there a simple w

Answer 1

EDIT - answer changed to address MC ND's comment

The solution is so simple :-) "%~f1.\file.ext"

Windows file names cannot end with . or , so all Windows commands simply ignore trailing . and in file/folder names.

And a single . following a backslash represents the current directory at that location.

Assume the current working directory is c:\test, then the table below show how various values get resolved:

"%~1"        | "%~f1.\file.ext"       | equivalent to
-------------+------------------------+------------------------
"c:\folder\" | "c:\folder\.\file.ext" | "c:\folder\file.ext"
             |                        |
"c:\folder"  | "c:\folder.\file.ext"  | "c:\folder\file.ext"
             |                        |
"c:\"        | "c:\.\file.ext"        | "c:\file.ext"
             |                        |
"c:"         | "c:\test.\file.ext"    | "c:\test\file.ext"
             |                        |
"."          | "c:\test.\file.ext"    | "c:\test\file.ext"
             |                        |
".."         | "c:\.\file.ext"        | "c:\file.ext"
             |                        |
   | "c:\test.\file.ext"    | "c:\test\file.ext"  I hadn't thought of this case
                                                            until I saw MC ND's answer

You can easily reduce the expression into the canonical equivalent form using a FOR loop:

for %%A in ("%~f1.\file.ext") do echo "%%~fA"

As Harry Johnston states in his comment, this solution does not work with UNC root paths (\\server\shareName) or long paths (\\?\c:\somePath). See MC ND's answer if you need to support either of those cases. The Harry Johnston answer is simpler, but it does not support the case of no argument given.