公司机器有一批是全新安装的ubuntu18 server版本，有一部分是从原来的ubuntu16.04升级过来的，在使用apt安装程序的时候不相同，升级的那批有时候apt update 失败或者apt install时
失败。这个时候需要替换源，源包括 /etc/apt/sources.list 里的配置和/etc/apt/sources.list.d/下面的文件里的配置。
问题1： 在apt install salt-minion时,报i386不支持
解决方法是，在源文件里加入 [arch=amd64]，加完后，如下配置：

root@sz-dev-vm-ubuntu69-64:/opt# cat  /etc/apt/sources.list.d/saltstack.list 
deb [arch=amd64]  http://repo.saltstack.com/apt/ubuntu/18.04/amd64/latest bionic main

问题2：报：

The following packages have unmet dependencies:
 salt-minion : Depends: python-zmq (>= 14.4.0) but it is not installable
               Depends: salt-common (= 2018.3.3+ds-2) but it is not going to be installed
               Recommends: debconf-utils but it is not installable
E: Unable to correct problems, you have held broken packages.

当前配置是：

oot@ubuntu18-ip54:~# cat /etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu bionic main
deb http://archive.ubuntu.com/ubuntu bionic-security main
deb http://archive.ubuntu.com/ubuntu bionic-updates main
root@ubuntu18-ip54:~# cat /etc/apt/sources.list.d/saltstack.list 
deb [arch=amd64]  http://repo.saltstack.com/apt/ubuntu/18.04/amd64/latest bionic main

解决方法：修改 /etc/apt/sources.list，为：

root@ubuntu18:/etc/apt# cat sources.list
#deb http://archive.ubuntu.com/ubuntu bionic main
#deb http://archive.ubuntu.com/ubuntu bionic-security main
#deb http://archive.ubuntu.com/ubuntu bionic-updates main

deb http://archive.ubuntu.com/ubuntu/ bionic main restricted
deb http://archive.ubuntu.com/ubuntu/ bionic-updates main restricted
deb http://archive.ubuntu.com/ubuntu/ bionic universe
deb http://archive.ubuntu.com/ubuntu/ bionic-updates universe
deb http://archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://archive.ubuntu.com/ubuntu/ bionic-updates multiverse
deb http://archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu/ bionic-security main restricted
deb http://security.ubuntu.com/ubuntu/ bionic-security universe
deb http://security.ubuntu.com/ubuntu/ bionic-security multiverse
root@ubuntu18:/etc/apt# cat sources.list.d/saltstack.list 

root@ubuntu18-ip54:~# cat /etc/apt/sources.list.d/saltstack.list 
deb [arch=amd64]  http://repo.saltstack.com/apt/ubuntu/18.04/amd64/latest bionic main

之后，可成功安装。

在网上搜不到解决答案，所以记录下来，给遇到相同问题的小伙伴一点帮助。