Working Directory Independence for Batch Files

%~p0\

(or: Many times your batch file will want to access resources in the same folder as the batch file. This can be tricky if the user calls the batch file from another folder, since the working directory is not the directory the batch file is in. Rather that resorting to pushd / popd everywhere, one can use the extended command line parameter handling to convert the full path to the batch file into a relative path to it’s container. %0 is the path the batch was called with, so %~p0 is the path to that location)

Access denied when piping to :Null

It's quite a common thing in my batch files (yes, .BAT is still alive) to limit the verbosity of the output displayed to the user. It's a 'seeing-the-wood-for-the-trees' thing: I don't want to have the user waide through screens of output to know that a CACLS worked ok (and potentially miss something important)

So I quieten things down by piping to null:

aspnet_setreg -k:SOFTWARE\MyCompany\MyApp -u:"%username%" -p:"%password%" >:null

...and listen for ERRORLEVEL instead.

But recently I discovered that this fails with Access Denied if you don't have write permissions to the current directory (yes, you need write permissions to write to :null. Just don't ask). Not only that, but the whole statement fails, not just the piping bit.

So these days I pipe to %temp%\null instead.