Artisan Tinker - Getting command history

Artisan Tinker is an Artisan command. You can view its source here. TinkerCommand contains the following:

public function fire()
{
	if ($this->supportsBoris())
	{
		$this->runBorisShell();
	}
	else
	{
		$this->comment('Full REPL not supported. Falling back to simple shell.');
		$this->runPlainShell();
	}
}

so it uses the Boris shell (if supported). Boris.php contains an private property called $historyFile. If you look at where Boris is instantiated, you'll probably find that the history file is located in ~/.boris_history:

cat ~/.boris_history
_HiStOrY_V2_
User::all()->toArray();
exit;