How to set a dummy scoreboard objective to another dummy

Solution 1:

There is a better way of solving your problem. Instead of creating a new dummy objective, you can simply reset the jumps objective to 0 every tick.

You would need to run the following command once:

/scoreboard objectives add jumps stat.jump

And these on a clock:

/execute @a[score_jumps_min=1] ~ ~ ~ do stuff
/scoreboard players set @a[score_jumps_min=1] jumps 0

Of course you replace do stuff with the command/function you actually want to run.

If you're still interested in solving the exact problem you posed, there is a different /scoreboard 'subcommand' that can do that: operation. The following command sets the command executor's oldtotaljumps score to its totaljumps score.

/scoreboard players operation @s oldtotaljumps = @s totaljumps