mongodb的安装：

1.MongoDB 源码下载地址：https://www.mongodb.com/download-center#community

2.vim /etc/profile修改环境变量：末尾添加

export PATH=$PATH:/home/no4/mongodb/bin

3.source /etc/profile

避免每次都要使用source /etc/profile使环境变量文件生效的方法：

sudo su
vim ~/.bashrc

末尾添加source /etc/profile

4.新建配置文件mongod.conf

systemLog:
    destination: file
    path: "/home/no4/mongodata/log/mongod.log"
    logAppend: true
storage:
    dbPath: "/home/no4/mongodata/db"
    journal:
       enabled: true
processManagement:
    fork: true
net:
    bindIp: localhost
    port: 27017

5.在配置文件所指定的位置建立对应的文件夹

6.mongod -f /home/no4/mongodb/mongod.conf命令启动mongodb服务器，正常输出如下：

root@no4-Default-string:/home/no4# mongod -f ./mongodb/mongod.conf
about to fork child process, waiting until server is ready for connections.
forked process: 11330
child process started successfully, parent exiting

如果是这样：

root@no4-Default-string:/home/no4# mongod -f ./mongodb/mongod.conf
about to fork child process, waiting until server is ready for connections.
forked process: 11306
ERROR: child process failed, exited with 48
To see additional information in this output, start without the "--fork" option.

一般是因为之前已经启动过了mongodb，使用ps -ef|grep mongod查找mongod相关进程，然后杀掉后再重试。

7.输入mongo连接服务器，再输入show dbs查看数据库，正常输出如下：

> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB