dockerfile创建ubuntu，postfix配置选择时停止

Question

dockerfile创建ubuntu16.04,官网源

ubuntu安装完成，执行dockerfile后续命令。

到这一步，

RUN apt-get install -y dovecot-imapd dovecot-pop3d postfix

终端dovecot安装完，postfix安装时出现选择项：

Selecting previously unselected package postfix.
Preparing to unpack .../postfix_3.1.0-3_amd64.deb ...
debconf: unable to initialize frontend: Dialog
debconf: (TERM is not set, so the dialog frontend is not usable.)
debconf: falling back to frontend: Readline
Postfix Configuration
---------------------
 
Please select the mail server configuration type that best meets your needs.
 
 No configuration:
  Should be chosen to leave the current configuration unchanged.
 Internet site:
  Mail is sent and received directly using SMTP.
 Internet with smarthost:
  Mail is received directly using SMTP or by running a utility such
  as fetchmail. Outgoing mail is sent using a smarthost.
 Satellite system:
  All mail is sent to another machine, called a 'smarthost', for delivery.
 Local only:
  The only delivered mail is the mail for local users. There is no network.
 
  1. No configuration  3. Internet with smarthost  5. Local only
  2. Internet Site     4. Satellite system
General type of mail configuration:

上面我选了2，然后就没有任何动静了。。。。。

网上有说用apt-get install -y -o Options::="2" postfix 实验无果.
怎样才能自动安装选择呢？

Answer 1

 

echo "postfix postfix/main_mailer_type string 'Internet Site'" | debconf-set-selections 
&& echo "postfix postfix/mailname string 'mailname'" | debconf-set-selections