hadoop dfs、hadoop fs和hdfs dfs的区别

结论

hadoop fs命令的官方解释为“This command is documented in the File System Shell Guide. It is a synonym for `hdfs dfs` when HDFS is in use.”。即fs是一种通用的文件系统操作命令，当文件系统使用hdfs时，hadoop fs和hdfs dfs命令等效。

hdfs dfs命令的官方解释为“Run a filesystem command on the file system supported in Hadoop.”。即hdfs文件系统的操作命令。

hadoop dfs命令已经废弃不同，建议使用hdfs dfs命令。

对于HDFS而言，hadoop fs、hdfs dfs和hadoop dfs命令等效，但是hadoop dfs命令已废弃。

执行 hdfs 命令后可以看到如下帮助信息：

Usage: hdfs [--config confdir] [--loglevel loglevel] COMMAND
       where COMMAND is one of:
  dfs                  run a filesystem command on the file systems supported in Hadoop.
  classpath            prints the classpath
  namenode -format     format the DFS filesystem
  secondarynamenode    run the DFS secondary namenode
  namenode             run the DFS namenode
  journalnode          run the DFS journalnode
  zkfc                 run the ZK Failover Controller daemon
  datanode             run a DFS datanode
  dfsadmin             run a DFS admin client
  haadmin              run a DFS HA admin client
  fsck                 run a DFS filesystem checking utility
  balancer             run a cluster balancing utility
  jmxget               get JMX exported values from NameNode or DataNode.
  mover                run a utility to move block replicas across
                       storage types
  oiv                  apply the offline fsimage viewer to an fsimage
  oiv_legacy           apply the offline fsimage viewer to an legacy fsimage
  oev                  apply the offline edits viewer to an edits file
  fetchdt              fetch a delegation token from the NameNode
  getconf              get config values from configuration
  groups               get the groups which users belong to
  snapshotDiff         diff two snapshots of a directory or diff the
                       current directory contents with a snapshot
  lsSnapshottableDir   list all snapshottable dirs owned by the current user
                                                Use -help to see options
  portmap              run a portmap service
  nfs3                 run an NFS version 3 gateway
  cacheadmin           configure the HDFS cache
  crypto               configure HDFS encryption zones
  storagepolicies      list/get/set block storage policies
  version              print the version

Most commands print help when invoked w/o parameters.

执行 hadoop fs 命令可以看到如下提示：

Usage: hadoop fs [generic options]
        [-appendToFile  ... ]
        [-cat [-ignoreCrc]  ...]
        [-checksum  ...]
        [-chgrp [-R] GROUP PATH...]
        [-chmod [-R]  PATH...]
        [-chown [-R] [OWNER][:[GROUP]] PATH...]
        [-copyFromLocal [-f] [-p] [-l]  ... ]
        [-copyToLocal [-p] [-ignoreCrc] [-crc]  ... ]
        [-count [-q] [-h]  ...]
        [-cp [-f] [-p | -p[topax]]  ... ]
        [-createSnapshot  []]
        [-deleteSnapshot  ]
        [-df [-h] [ ...]]
        [-du [-s] [-h]  ...]
        [-expunge]
        [-find  ...  ...]
        [-get [-p] [-ignoreCrc] [-crc]  ... ]
        [-getfacl [-R] ]
        [-getfattr [-R] {-n name | -d} [-e en] ]
        [-getmerge [-nl]  ]
        [-help [cmd ...]]
        [-ls [-d] [-h] [-R] [ ...]]
        [-mkdir [-p]  ...]
        [-moveFromLocal  ... ]
        [-moveToLocal  ]
        [-mv  ... ]
        [-put [-f] [-p] [-l]  ... ]
        [-renameSnapshot   ]
        [-rm [-f] [-r|-R] [-skipTrash]  ...]
        [-rmdir [--ignore-fail-on-non-empty]  ...]
        [-setfacl [-R] [{-b|-k} {-m|-x } ]|[--set  ]]
        [-setfattr {-n name [-v value] | -x name} ]
        [-setrep [-R] [-w]   ...]
        [-stat [format]  ...]
        [-tail [-f] ]
        [-test -[defsz] ]
        [-text [-ignoreCrc]  ...]
        [-touchz  ...]
        [-truncate [-w]   ...]
        [-usage [cmd ...]]

Generic options supported are
-conf      specify an application configuration file
-D             use value for given property
-fs       specify a namenode
-jt     specify a ResourceManager
-files     specify comma separated files to be copied to the map reduce cluster
-libjars     specify comma separated jar files to include in the classpath.
-archives     specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]