Formatting the Windows date in a filename.

I’ve often needed to date an output file or backup folder created from a Windows script. The %DATE% variable cannot be used on it’s own because it returns a value with slashes in.
This method formats it to the ISO standard YYYYMMDD

echo %date:~6,4%-%date:~3,2%-%date:~0,2%
2012-05-16

Example- Backing up files to a dated folder

robocopy "C:\My Source Documents" "D:\My Backup Documents\%date:~6,4%-%date:~3,2%-%date:~0,2%" /MIR