Hadoop HDFS学习之HDFS的常用Shell操作

一、基本语法

bin/hadoop fs 具体命令 OR bin/hdfs dfs 具体命令
dfs是fs的实现类。

二、命令大全

cd /opt/module/hadoop-2.10.1/
bin/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] <localsrc> ... <dst>]
	[-copyToLocal [-f] [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
	[-count [-q] [-h] [-v] [-t [<storage type>]] [-u] [-x] <path> ...]
	[-cp [-f] [-p | -p[topax]] [-d] <src> ... <dst>]
	[-createSnapshot <snapshotDir> [<snapshotName>]]
	[-deleteSnapshot <snapshotDir> <snapshotName>]
	[-df [-h] [<path> ...]]
	[-du [-s] [-h] [-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>]
	[-help [cmd ...]]
	[-ls [-C] [-d] [-h] [-q] [-R] [-t] [-S] [-r] [-u] [<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] <file>]
	[-test -[defsz] <path>]
	[-text [-ignoreCrc] <src> ...]
	[-touchz <path> ...]
	[-truncate [-w] <length> <path> ...]
	[-usage [cmd ...]]

三、常用命令实操

1、启动Hadoop集群

在NameNode所在服务器启动hdfs：
cd /opt/module/hadoop-2.10.1/
sbin/start-dfs.sh

在ResourceManager所在服务器启动yarn：
cd /opt/module/hadoop-2.10.1/
sbin/start-yarn.sh

2、-help：输出这个命令参数

hadoop fs -help rm

3、-ls：显示目录信息

查看当前：
hadoop fs -ls /

递归查看所有：
hadoop fs -lsr /
hadoop fs -ls -R /

4、-mkdir：在HDFS上创建目录

hadoop fs -mkdir -p /sanguo/shuguo

5、-moveFromLocal：从本地剪切粘贴到HDFS

touch panjinlian.txt
vim panjinlian.txt
输入：
wo shi pan jin lian
hadoop fs -moveFromLocal ./panjinlian.txt /sanguo/shuguo

6、-appendToFile：追加一个文件到已经存在的文件末尾

touch liubei.txt
vim liubei.txt
输入：wo shi liu bei
hadoop fs -appendToFile ./liubei.txt /sanguo/shuguo/panjinlian.txt

7、-cat：显示文件内容

hadoop fs -cat /sanguo/shuguo/panjinlian.txt

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

hadoop fs -chgrp liuwenqing /sanguo/shuguo/panjinlian.txt
hadoop fs -chmod 666 /sanguo/shuguo/panjinlian.txt
hadoop fs -chown liuwenqing:liuwenqing /sanguo/shuguo/panjinlian.txt

9、-copyFromLocal：从本地文件系统中拷贝文件到HDFS路径去

touch ximenqing.txt
vim ximenqing.txt
输入：wo shi xi men qing
hadoop fs -copyFromLocal ./ximenqing.txt /sanguo/shuguo/

10、-copyToLocal：从HDFS拷贝到本地

hadoop fs -copyToLocal /sanguo/shuguo/panjinlian.txt ./

11、-cp ：从HDFS的一个路径拷贝到HDFS的另一个路径

hadoop fs -cp /sanguo/shuguo/panjinlian.txt /sanguo/

12、-mv：在HDFS目录中移动文件

hadoop fs -mv /sanguo/panjinlian.txt /

13、-get：等同于copyToLocal，就是从HDFS下载文件到本地

hadoop fs -get /panjinlian.txt ./

14、-getmerge：合并下载多个文件，比如HDFS的目录 /sanguo/shuguo下有多个文件:log.1, log.2,log.3,…

hadoop fs -getmerge /sanguo/shuguo/* ./zaiyiqi.txt

15、-put：等同于copyFromLocal

 hadoop fs -put ./LICENSE.txt /sanguo/shuguo/

16、-tail：显示一个文件的末尾

hadoop fs -tail /sanguo/shuguo/LICENSE.txt

17、-rm：删除文件或文件夹

hadoop fs -rm /sanguo/shuguo/LICENSE.txt

18、-rmdir：删除空目录

hadoop fs -mkdir /test
hadoop fs -rmdir /test

19、-du统计文件夹的大小信息

hadoop fs -du /
hadoop fs -du -h /
hadoop fs -du -h -s /

20、-setrep：设置HDFS中文件的副本数量

hadoop fs -setrep 10 /sanguo/shuguo/panjinlian.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。