I think use watch command is much easier, for example: watch {your command}
In your case, it will be:

watch vcgencmd measure_temp

That will refresh by 2 seconds, if you want to define the interval by yourself(5 second maybe), you can type:

watch -n 5

In your case, it will be:

watch -n 5 vcgencmd measure_temp

You can cancel that with Ctrl+C.

I think using watch command is much easier, for example:

watch {your command}

In your case, it will be:

watch vcgencmd measure_temp

That will refresh by 2 seconds, if you want to define the interval by yourself  (5 second maybe), you can type:

watch -n 5 <your command>

In your case, it will be:

watch -n 5 vcgencmd measure_temp

You can cancel that with Ctrl+C.