OS version: CentOS7 / Debian9
發現alien這個命令時很驚喜，之前在debian上安裝etcd找不到安裝包感覺很不科學，有了alien命令事情一下就變簡單了。
這里以etcd為例，將etcd從rpm包轉換成deb包，然后傳送到debian機器上安裝。(這個命令也可以把deb包轉換成rpm包)
1、找一臺centos機器，下載etd安裝包
在centos上下載rpm包需要安裝一個插件
# yum install -y yum-plugin-downloadonly
下載rpm包
# yum install etcd --downloadonly --downloaddir=/tmp/
這時，在/tmp下就能看到剛才下載的包了。
2、找一臺debian機器測試安裝
# dpkg -i etcd_3.2.9-4_amd64.deb
Selecting previously unselected package etcd.
(Reading database ... 87613 files and directories currently installed.)
Preparing to unpack etcd_3.2.9-4_amd64.deb ...
Unpacking etcd (3.2.9-4) ...
Setting up etcd (3.2.9-4) ...
/var/lib/dpkg/info/etcd.postinst: line 6: [: configure: integer expression expected
Processing triggers for man-db (2.7.6.1-2) ...
# etcd --version
etcd Version: 3.2.9
Git SHA: f1d7dd8
Go Version: go1.8.3
Go OS/Arch: linux/amd64
# dpkg -L etcd
# systemctl start etcd
# systemctl status etcd
● etcd.service - Etcd Server
Loaded: loaded (/usr/lib/systemd/system/etcd.service; enabled; vendor preset: enabled)
Active: active (running) since Fri 2018-01-05 10:51:34 CST; 7s ago
Main PID: 20249 (etcd)
CPU: 85ms
CGroup: /system.slice/etcd.service
└─20249 /usr/bin/etcd --name=default --data-dir=/var/lib/etcd/default.etcd --listen-client-urls=http://localhost:2379
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: 8e9e05c52164694d received MsgVoteResp from 8e9e05c52164694d at term 2
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: 8e9e05c52164694d became leader at term 2
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: raft.node: 8e9e05c52164694d elected leader 8e9e05c52164694d at term 2
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: setting up the initial cluster version to 3.2
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: published {Name:default ClientURLs:[http://localhost:2379]} to cluster cdf818194e3a8c32
Jan 05 10:51:34 BJ-S-22-v06 systemd[1]: Started Etcd Server.
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: ready to serve client requests
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: serving insecure client requests on 127.0.0.1:2379, this is strongly discouraged!
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: set the initial cluster version to 3.2
Jan 05 10:51:34 BJ-S-22-v06 etcd[20249]: enabled capabilities for version 3.2
)
