一：基本语法

hadoop fs 具体命令
hdfs dfs 具体命令
两者是完全相同的！

二：命令大全

[ghost@hadoop100 ~]$ hdfs dfs
Usage: hadoop fs [generic options]
	[-appendToFile <localsrc> ... <dst>]
	[-cat [-ignoreCrc] <src> ...]
	[-checksum [-v] <src> ...]
	[-chgrp [-R] GROUP PATH...]
	[-chmod [-R] <MODE[,MODE]... | OCTALMODE> PATH...]
	[-chown [-R] [OWNER][:[GROUP]] PATH...]
	[-concat <target path> <src path> <src path> ...]
	[-copyFromLocal [-f] [-p] [-l] [-d] [-t <thread count>] [-q <thread pool queue size>] <localsrc> ... <dst>]
	[-copyToLocal [-f] [-p] [-crc] [-ignoreCrc] [-t <thread count>] [-q <thread pool queue size>] <src> ... <localdst>]
	[-count [-q] [-h] [-v] [-t [<storage type>]] [-u] [-x] [-e] [-s] <path> ...]
	[-cp [-f] [-p | -p[topax]] [-d] [-t <thread count>] [-q <thread pool queue size>] <src> ... <dst>]
	[-createSnapshot <snapshotDir> [<snapshotName>]]
	[-deleteSnapshot <snapshotDir> <snapshotName>]
	[-df [-h] [<path> ...]]
	[-du [-s] [-h] [-v] [-x] <path> ...]
	[-expunge [-immediate] [-fs <path>]]
	[-find <path> ... <expression> ...]
	[-get [-f] [-p] [-crc] [-ignoreCrc] [-t <thread count>] [-q <thread pool queue size>] <src> ... <localdst>]
	[-getfacl [-R] <path>]
	[-getfattr [-R] {-n name | -d} [-e en] <path>]
	[-getmerge [-nl] [-skip-empty-file] <src> <localdst>]
	[-head <file>]
	[-help [cmd ...]]
	[-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [-e] [<path> ...]]
	[-mkdir [-p] <path> ...]
	[-moveFromLocal [-f] [-p] [-l] [-d] <localsrc> ... <dst>]
	[-moveToLocal <src> <localdst>]
	[-mv <src> ... <dst>]
	[-put [-f] [-p] [-l] [-d] [-t <thread count>] [-q <thread pool queue size>] <localsrc> ... <dst>]
	[-renameSnapshot <snapshotDir> <oldName> <newName>]
	[-rm [-f] [-r|-R] [-skipTrash] [-safely] <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] [-s <sleep interval>] <file>]
	[-test -[defswrz] <path>]
	[-text [-ignoreCrc] <src> ...]
	[-touch [-a] [-m] [-t TIMESTAMP (yyyyMMdd:HHmmss) ] [-c] <path> ...]
	[-touchz <path> ...]
	[-truncate [-w] <length> <path> ...]
	[-usage [cmd ...]]

Generic options supported are:
-conf <configuration file>        specify an application configuration file
-D <property=value>               define a value for a given property
-fs <file:///|hdfs://namenode:port> specify default filesystem URL to use, overrides 'fs.defaultFS' property from configurations.
-jt <local|resourcemanager:port>  specify a ResourceManager
-files <file1,...>                specify a comma-separated list of files to be copied to the map reduce cluster
-libjars <jar1,...>               specify a comma-separated list of jar files to be included in the classpath
-archives <archive1,...>          specify a comma-separated list of archives to be unarchived on the compute machines

The general command line syntax is:
command [genericOptions] [commandOptions]

三：常用命令实操

3.1 准备工作

启动 Hadoop 集群

-help：查看对应命令的解释

[ghost@hadoop100 ~]$ hdfs dfs -help du
-du [-s] [-h] [-v] [-x] <path> ... :
  Show the amount of space, in bytes, used by the files that match the specified
  file pattern. The following flags are optional:
                                                                                 
  -s  Rather than showing the size of each individual file that matches the      
      pattern, shows the total (summary) size.                                   
  -h  Formats the sizes of files in a human-readable fashion rather than a number
      of bytes.                                                                  
  -v  option displays a header line.                                             
  -x  Excludes snapshots from being counted.                                     
  
  Note that, even without the -s option, this only shows size summaries one level
  deep into a directory.
  
  The output is in the form 
  	size	disk space consumed	name(full path)

创建 /sanguo 文件夹

1	[ghost@hadoop100 ~]$ hdfs dfs -mkdir /sanguo

Browsing HDFS

3.2 上传

（1）-moveFromLocal：从本地剪切粘贴到 HDFS

1	[ghost@hadoop100 tmp]$ hdfs dfs -moveFromLocal ./shuguo.txt /sanguo

（2）-copyFromLocal：从本地文件系统中拷贝文件到 HDFS 路径去

1	[ghost@hadoop100 tmp]$ hdfs dfs -copyFromLocal ./shuguo2.txt /sanguo

（3）-put：等同于 copyFromLocal，生产环境更习惯用 put

1	[ghost@hadoop100 tmp]$ hdfs dfs -put ./weiguo.txt /sanguo

（4）-appendToFile：追加一个文件到已经存在的文件末尾

1	[ghost@hadoop100 tmp]$ hdfs dfs -appendToFile ./wuguo.txt /sanguo/shuguo2.txt

3.3 下载

（1）-copyToLocal：从HDFS拷贝到本地

1	[ghost@hadoop100 sanguo]$ hdfs dfs -copyToLocal /sanguo/shuguo.txt ./

（2）-get：等同于 -copyToLocal，生产环境惯用

1	[ghost@hadoop100 sanguo]$ hdfs dfs -get /sanguo/shuguo2.txt ./

3.4 HDFS 直接操作

（1）-ls: 显示目录信息

[ghost@hadoop100 sanguo]$ hdfs dfs -ls /
Found 2 items
drwxr-xr-x   - ghost supergroup          0 2022-12-14 19:15 /sanguo
drwxrwx---   - ghost supergroup          0 2022-12-14 15:24 /tmp

（2）-cat：显示文件内容

1 2	[ghost@hadoop100 sanguo]$ hdfs dfs -cat /sanguo/shuguo.txt shuguo

（3）-chgrp、-chmod、-chown：Linux 文件系统中的用法一样，修改文件所属权限

1	[ghost@hadoop100 sanguo]$ hdfs dfs -chown ghost:ghost /sanguo/shuguo.txt

（4）-mkdir：创建路径

1	[ghost@hadoop100 sanguo]$ hdfs dfs -mkdir /jinguo

（5）-cp：从 HDFS 的一个路径拷贝到 HDFS 的另一个路径

1	[ghost@hadoop100 sanguo]$ hdfs dfs -cp /sanguo/* /jinguo

（6）-mv：在 HDFS 目录中移动文件

1	[ghost@hadoop100 sanguo]$ hdfs dfs -mv /sanguo /jinguo

（7）-tail：显示一个文件的末尾 1kb 的数据

1	[ghost@hadoop100 sanguo]$ hdfs dfs -tail /jinguo/weiguo.txt

（8）-rm：删除文件或文件夹

1	[ghost@hadoop100 sanguo]$ hdfs dfs -rm /sanguo/shuguo2.txt

（9）-rm -r：递归删除目录及目录里面内容

1 2	# jinguo 文件夹也被删除 [ghost@hadoop100 sanguo]$ hdfs dfs -rm -r /jinguo/

（10）-du 统计文件夹的大小信息

[ghost@hadoop100 sanguo]$ hdfs dfs -du /jinguo
7  21  /jinguo/shuguo.txt
7  21  /jinguo/weiguo.txt

# 查看总容量
[ghost@hadoop100 sanguo]$ hdfs dfs -du -s /jinguo
14  42  /jinguo

（11）-setrep：设置 HDFS 中文件的副本数量

1	[ghost@hadoop100 sanguo]$ hdfs dfs -setrep 2 /jinguo/weiguo.txt

这里设置的副本数只是记录在 NameNode 的元数据中，是否真的会有这么多副本，还得看 DataNode 的数量。因为目前只有 3 台设备，最多也就 3 个副本，只有节点数的增加到 10 台时，副本数才能达到 10。同一份副本一个节点上只会存一份！