1. 基本语法
hadoop fs 具体命令或者hadoop dfs 具体命令。
两个是完全相同的。
2. 命令大全
hadoop fs：
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] [-d] [-t <thread count>] <localsrc> ... <dst>]
[-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
[-count [-q] [-h] [-v] [-t [<storage type>]] [-u] [-x] [-e] <path> ...]
[-cp [-f] [-p | -p[topax]] [-d] <src> ... <dst>]
[-createSnapshot <snapshotDir> [<snapshotName>]]
[-deleteSnapshot <snapshotDir> <snapshotName>]
[-df [-h] [<path> ...]]
[-du [-s] [-h] [-v] [-x] <path> ...]
[-expunge]
[-find <path> ... <expression> ...]
[-get [-f] [-p] [-ignoreCrc] [-crc] <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 <localsrc> ... <dst>]
[-moveToLocal <src> <localdst>]
[-mv <src> ... <dst>]
[-put [-f] [-p] [-l] [-d] <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 -[defsz] <path>]
[-text [-ignoreCrc] <src> ...]
[-touch [-a] [-m] [-t TIMESTAMP ] [-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]
2.1 help命令
hadoop fs -help 命令
比如：
[hexuan@hadoop102 ~]$ hadoop fs -help ls
-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [-e] [<path> ...] :
List the contents that match the specified file pattern. If path is not
specified, the contents of /user/<currentUser> will be listed. For a directory a
list of its direct children is returned (unless -d option is specified).
Directory entries are of the form:
permissions - userId groupId sizeOfDirectory(in bytes)
modificationDate(yyyy-MM-dd HH:mm) directoryName
and file entries are of the form:
permissions numberOfReplicas userId groupId sizeOfFile(in bytes)
modificationDate(yyyy-MM-dd HH:mm) fileName
-C Display the paths of files and directories only.
-d Directories are listed as plain files.
-h Formats the sizes of files in a human-readable fashion
rather than a number of bytes.
-q Print ? instead of non-printable characters.
-R Recursively list the contents of directories.
-t Sort files by modification time (most recent first).
-S Sort files by size.
-r Reverse the order of the sort.
-u Use time of last access instead of modification for
display and sorting.
-e Display the erasure coding policy of files and directories.
2.2 上传
（1）-moveFromLocal ：从本地剪切黏贴到HDFS
[hexuan@hadoop102 ~]$ vim wuguo.txt
[hexuan@hadoop102 ~]$ hadoop fs -moveFromLocal wuguo.txt /sanguo/
2024-09-04 10:39:14,395 INFO sasl.SaslDataTransferClient: SASL encryption trust check: localHostTrusted = false, remoteHostTrusted = false
（2）-copyFromLocal：从本地文件系统拷贝文件到HDFS中。
hadoop fs -copyFromLocal wuguo.txt /sanguo/
（3）-put：等同于copyFromLocal，生产环境更习惯于用put。
hadoop fs -put wuguo.txt /sanguo/（4）-appendToFile：追加一个文件到已经存在的文件末尾。
2.3 下载
（1）-copyToLocal：从HDFS拷贝到本地
（2）-get：等同于copyToLocal，生产环境中更常用get。
[hexuan@hadoop102 ~]$ hadoop fs -get /sanguo/wuguo.txt ./wuguo_copy.txt
2024-09-04 10:59:00,847 INFO sasl.SaslDataTransferClient: SASL encryption trust check: localHostTrusted = false, remoteHostTrusted = false
2.4 其他命令
（1）-ls：显示目录信息。
（2）-cat：显示文件内容。
（3）-chgrp，-chmod，-chown：与Linux系统中的用法一致，修改文件的权限。
（4）-mkdir：创建文件目录。
（5）-cp：从HDFS的一个路径复制到另一个路径。
（6）-mv：在HDFS中移动文件。
（7）-tail：显示一个文件的末尾1kb的数据。
（8）-rm：删除文件或文件夹。
（9）-rm -r：递归删除目录和目录里的内容。
（10）-du：统计文件夹的大小信息。
[hexuan@hadoop102 ~]$ hadoop fs -du /sanguo
40 120 /sanguo/jiangwei.txt._COPYING_
0 0 /sanguo/simayi.txt
12 36 /sanguo/wuguo.txt
[hexuan@hadoop102 ~]$ hadoop fs -du -s /sanguo
52 156 /sanguo
说明：
40， 12， 52表示的都是文件大小，120表示的是40*3个副本，/sanguo表示查看的目录。
添加选项-s显示文件夹整体的信息。
（11）-setrep：设置HDFS中文件的副本数量
[hexuan@hadoop102 ~]$ hadoop fs -setrep 10 /sanguo/wuguo.txt
Replication 10 set: /sanguo/wuguo.txt
这里设置的副本数只是记录在NameNode的元数据，是否真的会有这么多副本，还得看DataNode的数量。目前只有三台设备，所以最多也就三个副本，只有当节点数达到10台，副本数才能到10个。
