我有一台 CentOS 7 的服务器，我想安装 mongoDB。我尝试安装它，输入：
sudo yum install mongodb
没有任何问题，那么我mongod得到：
-bash: mongod: command not found
如果我这样做，mongo我只会得到：
2017-04-22T21:09:55.078+0000 warning: Failed to connect to 127.0.0.1:27017, reason: errno:111 Connection refused
2017-04-22T21:09:55.079+0000 Error: couldn't connect to server 127.0.0.1:27017 (127.0.0.1), connection attempt failed at src/mongo/shell/mongo.js:146
因此，我尝试按照以下方法再次安装本说明但当我输入时 sudo yum install -y mongodb-org我得到：
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: centos.mirror.constant.com
* epel: mirror.math.princeton.edu
* extras: mirror.netdepot.com
* updates: mirror.cc.columbia.edu
Resolving Dependencies
--> Running transaction check
---> Package mongodb-org.x86_64 0:3.4.4-1.el7 will be installed
--> Processing Dependency: mongodb-org-tools = 3.4.4 for package: mongodb-org-3.4.4-1.el7.x86_64
--> Processing Dependency: mongodb-org-shell = 3.4.4 for package: mongodb-org-3.4.4-1.el7.x86_64
--> Processing Dependency: mongodb-org-server = 3.4.4 for package: mongodb-org-3.4.4-1.el7.x86_64
--> Processing Dependency: mongodb-org-mongos = 3.4.4 for package: mongodb-org-3.4.4-1.el7.x86_64
--> Running transaction check
---> Package mongodb-org-mongos.x86_64 0:3.4.4-1.el7 will be installed
---> Package mongodb-org-server.x86_64 0:3.4.4-1.el7 will be installed
---> Package mongodb-org-shell.x86_64 0:3.4.4-1.el7 will be installed
---> Package mongodb-org-tools.x86_64 0:3.4.4-1.el7 will be installed
--> Processing Conflict: mongodb-org-server-3.4.4-1.el7.x86_64 conflicts mongodb
--> Processing Conflict: mongodb-org-3.4.4-1.el7.x86_64 conflicts mongodb
--> Processing Conflict: mongodb-org-shell-3.4.4-1.el7.x86_64 conflicts mongodb
--> Processing Conflict: mongodb-org-mongos-3.4.4-1.el7.x86_64 conflicts mongodb
--> Processing Conflict: mongodb-org-tools-3.4.4-1.el7.x86_64 conflicts mongodb
--> Finished Dependency Resolution
Error: mongodb-org-mongos conflicts with mongodb-2.6.12-4.el7.x86_64
Error: mongodb-org-shell conflicts with mongodb-2.6.12-4.el7.x86_64
Error: mongodb-org-tools conflicts with mongodb-2.6.12-4.el7.x86_64
Error: mongodb-org conflicts with mongodb-2.6.12-4.el7.x86_64
Error: mongodb-org-server conflicts with mongodb-2.6.12-4.el7.x86_64
You could try using --skip-broken to work around the problem
You could try running: rpm -Va --nofiles --nodigest
这让我抓狂。我读到yum makecache重新安装可以解决我的问题，但并没有。还尝试卸载所有内容， sudo yum erase $(rpm -qa | grep mongodb-org)但结果却显示：
Loaded plugins: fastestmirror
Error: Need to pass a list of pkgs to erase
Mini usage:
erase PACKAGE...
Remove a package or packages from your system
aliases: remove, autoremove, erase-n, erase-na, erase-nevra, autoremove-n, autoremove-na, autoremove-nevra, remove-n, remove-na, remove-nevra
那么，我还能做什么？我只需要运行 mongo。谢谢！
答案1
您已经mongodb-2.6.12-4.el7.x86_64安装（最有可能来自 EPEL 仓库 - 我只是猜测，因为您没有指定）并正在尝试从 MongoDB 仓库安装另一个版本。
请尝试以下操作：
yum remove mongodb*
yum clean all
yum install mongodb-org
不要使用-y。yum花点时间阅读屏幕上的内容，尤其是对你来说很新的内容。