运行[alternatives --config mta]时会出现以下屏幕.
There are 2 programs which provide 'mta'.
Selection Command
-----------------------------------------------
+ 1 /usr/sbin/sendmail.postfix
* 2 /usr/sbin/sendmail.sendmail
Enter to keep the current selection[+], or type selection number:
星号是什么意思？
请帮我.