环境：Linux，MongoDB版本2.2.2：

MongoDB的安装和启动都比较简单
1.解压 mongodb-linux-i686-2.2.2.tgz 到/usr/local/目录下：
这里我的目录是：/usr/local/mongodb2.2.2
2.创建两个路径：一个用来存放数据库文件，一个用来存放数据库日志文件
在这里我在：/usr/local/mongodb2.2.2目录下创建了data和logs目录
3.启动数据库：
使用如下命令启动数据库
./bin/mongod --dbpath=/usr/local/mongodb2.2.2/data/ --logpath=/usr/local/mongodb2.2.2/logs/db.log --fork
启动过程如：
[root@localhost mongodb2.2.2]# ./bin/mongod  --dbpath=/usr/local/mongodb2.2.2/data/ --logpath=/usr/local/mongodb2.2.2/logs/db.log --fork
forked process: 32093
all output going to: /usr/local/mongodb2.2.2/logs/db.log
log file [/usr/local/mongodb2.2.2/logs/db.log] exists; copied to temporary file [/usr/local/mongodb2.2.2/logs/db.log.2012-05-28T18-16-42]
child process started successfully, parent exiting

如果需要让数据库自动启动，可以把启动目录添加到Linux启动脚本项中
4.可通过查看logs目录中的db.log查看数据库的一些信息，如第一次启动数据库，能看到如下信息：

[root@localhost logs]# more db.log
Tue May 29 02:16:42
Tue May 29 02:16:42 warning: 32-bit servers don't have journaling enabled by default. Please use --journal if you want durability.
Tue May 29 02:16:42
Tue May 29 02:16:42 [initandlisten] MongoDB starting : pid=32093 port=27017 dbpath=/usr/local/mongodb2.2.2/data/ 32-bit host=localhost
Tue May 29 02:16:42 [initandlisten]
Tue May 29 02:16:42 [initandlisten] ** NOTE: when using MongoDB 32 bit, you are limited to about 2 gigabytes of data
Tue May 29 02:16:42 [initandlisten] **       see http://blog.mongodb.org/post/137788967/32-bit-limitations
Tue May 29 02:16:42 [initandlisten] **       with --journal, the limit is lower
Tue May 29 02:16:42 [initandlisten]
Tue May 29 02:16:42 [initandlisten] db version v2.2.2, pdfile version 4.5
Tue May 29 02:16:42 [initandlisten] git version: d1b43b61a5308c4ad0679d34b262c5af9d664267
Tue May 29 02:16:42 [initandlisten] build info: Linux domU-12-31-39-01-70-B4 2.6.21.7-2.fc8xen #1 SMP Fri Feb 15 12:39:36 EST 2008 i686 BOOST_LIB_VERSION=1_49
Tue May 29 02:16:42 [initandlisten] options: { dbpath: "/usr/local/mongodb2.2.2/data/", fork: true, logpath: "/usr/local/mongodb2.2.2/logs/db.log" }
Tue May 29 02:16:42 [initandlisten] Unable to check for journal files due to: boost::filesystem::basic_directory_iterator constructor: No such file or directory: "/usr/local/mong
odb2.2.2/data/journal"
Tue May 29 02:16:43 [websvr] admin web console waiting for connections on port 28017
Tue May 29 02:16:44 [initandlisten] waiting for connections on port 27017
从中可以看出数据库启动的端口号等信息。
5.进入数据库：
使用bin下面的mongo脚本：
进入如下命令行：
[root@localhost bin]# ./mongo
MongoDB shell version: 2.2.2
connecting to: test
>
>
>
使用mongo脚本进入连接上的是默认的test数据库。