如何以非交互方式安装apt软件包？

如果我运行：

sudo apt-get --yes install postfix 

要么

sudo bash -c 'yes | apt-get --yes install postfix'

出现交互式提示以配置后缀。我需要自动安装postfix（我可以在安装后修改配置文件）。

有什么魔术让我无需人工干预即可安装postfix（和其他软件包）的？

设置DEBIAN_FRONTEND为noninteractive：

DEBIAN_FRONTEND=noninteractive apt-get ...

这也适用于dpkg --reconfigure，dpkg-configure等等。

来自man 7 debconf：

noninteractive
      This  is  the anti-frontend. It never interacts with you at all,
      and makes the default answers be  used  for  all  questions.  It
      might  mail  error messages to root, but that's it; otherwise it
      is completely silent and unobtrusive,  a  perfect  frontend  for
      automatic installs. If you are using this front-end, and require
      non-default answers to questions, you will need to  preseed  the
      debconf  database;  see  the section below on Unattended Package
      Installation for more details.

如果您设置好了noninteractive，应该考虑debconf使用回答问题debconf-set-selections。