想在这里把一些自己用过常用的操作练习，总结一下备忘。其实基本上是是linux命令的一部分，这部分命令和linux中的用法基本一致。在使用时可以用$bin/hadoop fs来全部列出查看或者学习。
1. $bin/hadoop fs -ls path //列出目录下文件
2. $bin/hadoop fs -mkdir path //创建目录
3. $bin/hadoop fs -rm path //删除文件或者目录
4. $bin/hadoop fs -rmdir path //删除目录
5. $bin/hadoop fs -put localfile path //将文件从本地上传到HDFS的指定文件夹中
6. $bin/hadoop fs -cat filename //查看指定的文件内容
7. $bin/hadoop fs -get HDFSfile localfilename //将HDFS文件下载到本地，命名为localfilename
在日常开发中我们可以使用eclipse的mapreduce插件，直接在eclipse中开发MR程序，并且直接运行。在这个环境中HDFS就是可视化的，如下：
在这里可以右键实现
- 创建新目录
- 上传文件到DFS
- 上传目录到DFS
- 从DFS下载文件
- 删除DFS的目录或者文件
- 刷新以实现当前视窗和DFS的一致性
下面是hdfs现有的全部命令
Usage: hadoop fs [generic options]
[-appendToFile <localsrc> ... <dst>]
[-cat [-ignoreCrc] <src> ...]
[-checksum <src> ...]
[-chgrp [-R] GROUP PATH...]
[-chmod [-R] <MODE[,MODE]... | OCTALMODE> PATH...]
[-chown [-R] [OWNER][:[GROUP]] PATH...]
[-copyFromLocal [-f] [-p] [-l] <localsrc> ... <dst>]
[-copyToLocal [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
[-count [-q] [-h] <path> ...]
[-cp [-f] [-p | -p[topax]] <src> ... <dst>]
[-createSnapshot <snapshotDir> [<snapshotName>]]
[-deleteSnapshot <snapshotDir> <snapshotName>]
[-df [-h] [<path> ...]]
[-du [-s] [-h] <path> ...]
[-expunge]
[-find <path> ... <expression> ...]
[-get [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
[-getfacl [-R] <path>]
[-getfattr [-R] {-n name | -d} [-e en] <path>]
[-getmerge [-nl] <src> <localdst>]
[-help [cmd ...]]
[-ls [-d] [-h] [-R] [<path> ...]]
[-mkdir [-p] <path> ...]
[-moveFromLocal <localsrc> ... <dst>]
[-moveToLocal <src> <localdst>]
[-mv <src> ... <dst>]
[-put [-f] [-p] [-l] <localsrc> ... <dst>]
[-renameSnapshot <snapshotDir> <oldName> <newName>]
[-rm [-f] [-r|-R] [-skipTrash] <src> ...]
[-rmdir [--ignore-fail-on-non-empty] <dir> ...]
[-setfacl [-R] [{-b|-k} {-m|-x <acl_spec>} <path>]|[--set <acl_spec> <path>]]
[-setfattr {-n name [-v value] | -x name} <path>]
[-setrep [-R] [-w] <rep> <path> ...]
[-stat [format] <path> ...]
[-tail [-f] <file>]
[-test -[defsz] <path>]
[-text [-ignoreCrc] <src> ...]
[-touchz <path> ...]
[-truncate [-w] <length> <path> ...]
[-usage [cmd ...]]
Generic options supported are
-conf <configuration file> specify an application configuration file
-D <property=value> use value for given property
-fs <local|namenode:port> specify a namenode
-jt <local|resourcemanager:port> specify a ResourceManager
-files <comma separated list of files> specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars> specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives> specify comma separated archives to be unarchived on the compute machines.