This technique was developed to generate a timestamp string for rsync's --backup-dir option but it could be generally useful.
The first issue is that the value of %DATE% depends on Windows' regional settings so is not portable. The same goes for the output format of cmd.exe's builtin command
date. (one example of many discussions:
this StackOverflow thread). There is no way to program around this in a .BAT or .CMD script. The chosen solution was to
UnxUtils' date.exe which is a...
