I'm debugging a batch file left behind by an old employee and I've come across the line: 

```
@nmake -f makefile /E 2>&1 | tee %LOGFILEPATH%  

```

What does this do?  

I know what `@nmake -f makefile /E` does and I know what `tee %LOGFILEPATH%` does, but I can't find anything on what the `2>&1 |` means.  

Thanks