How to use random in BATCH script?

%RANDOM% gives you a random number between 0 and 32767.

You can control the number's range with:

set /a num=%random% %%100

- will produce number between 0~99.

This one:

set /a num=%random% %%100 +1

- will produce number between 1~100.

%RANDOM% gives you a random number between 0 and 32767.

Using an expression like SET /A test=%RANDOM% * 100 / 32768 + 1, you can change the range to anything you like (here the range is [1…100] instead of [0…32767]).