HDFS的Shell操作

1．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。

2．命令大全

[root@hadoop002 hadoop-2.7.2]# hdfs dfs
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.

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

3．常用命令实操

（0）启动Hadoop集群（方便后续的测试）

[atguigu@hadoop102 hadoop-2.7.2]$ sbin/start-dfs.sh

[atguigu@hadoop103 hadoop-2.7.2]$ sbin/start-yarn.sh

（1）-help：输出这个命令参数

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -help rm

（2）-ls: 显示目录信息

[root@hadoop002 hadoop-2.7.2]# hadoop fs -ls /
Found 2 items
-rw-r--r--   3 root supergroup   18284613 2020-01-15 12:11 /tools.jar
-rw-r--r--   3 root supergroup         48 2020-01-15 12:05 /wc.input

（3）-mkdir：在HDFS上创建目录

[root@hadoop002 hadoop-2.7.2]# hadoop fs -mkdir -p /wgr/test

（4）-moveFromLocal：从本地剪切粘贴到HDFS

[root@hadoop002 hadoop-2.7.2]# touch kongming.txt
[root@hadoop002 hadoop-2.7.2]# hadoop fs -moveFromLocal kongming.txt /wgr/test

（5）-appendToFile：追加一个文件到已经存在的文件末尾

[root@hadoop002 hadoop-2.7.2]# echo "testtestetetst" >> test.txt
[root@hadoop002 hadoop-2.7.2]# ll
total 80
drwxr-xr-x 2 root root  4096 Jan 14 22:19 bin
drwxr-xr-x 3 root root  4096 Jan 14 23:35 data
drwxr-xr-x 3 root root  4096 Jan 14 22:13 etc
-rw-r--r-- 1 root root     0 Jan 14 22:13 hdfs-site.xml
drwxr-xr-x 2 root root  4096 Jan 14 22:13 include
drwxr-xr-x 2 root root  4096 Jan 14 22:13 input
drwxr-xr-x 3 root root  4096 Jan 14 22:19 lib
drwxr-xr-x 2 root root  4096 Jan 14 22:13 libexec
-rw-r--r-- 1 root root 15429 Jan 14 22:13 LICENSE.txt
drwxr-xr-x 3 root root  4096 Jan 15 11:59 logs
-rw-r--r-- 1 root root   101 Jan 14 22:20 NOTICE.txt
drwxr-xr-x 2 root root  4096 Jan 14 22:19 output
-rw-r--r-- 1 root root  1366 Jan 14 22:20 README.txt
drwxr-xr-x 2 root root  4096 Jan 14 22:19 sbin
drwxr-xr-x 4 root root  4096 Jan 14 22:13 share
-rw-r--r-- 1 root root    15 Jan 15 22:27 test.txt
drwxr-xr-x 2 root root  4096 Jan 14 22:13 wcinput
drwxr-xr-x 2 root root  4096 Jan 14 22:13 wcoutput
[root@hadoop002 hadoop-2.7.2]# hadoop fs -appendToFile test.txt /wgr/test/kongming.txt

（6）-cat：显示文件内容

[root@hadoop002 hadoop-2.7.2]# hadoop fs -cat /wgr/test/kongming.txt
testtestetetst

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

[root@hadoop002 hadoop-2.7.2]# hadoop fs -chmod 777 /wgr/test/kongming.txt
[root@hadoop002 hadoop-2.7.2]# hadoop fs -cat /wgr/test/kongming.txt
testtestetetst
[root@hadoop002 hadoop-2.7.2]# hadoop fs -ls -R  /
-rw-r--r--   3 root supergroup   18284613 2020-01-15 12:11 /tools.jar
-rw-r--r--   3 root supergroup         48 2020-01-15 12:05 /wc.input
drwxr-xr-x   - root supergroup          0 2020-01-15 21:49 /wgr
drwxr-xr-x   - root supergroup          0 2020-01-15 21:51 /wgr/test
-rwxrwxrwx   3 root supergroup         15 2020-01-15 22:28 /wgr/test/kongming.txt

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

[root@hadoop002 hadoop-2.7.2]# hadoop fs -copyFromLocal README.txt /

（9）-copyToLocal：从HDFS拷贝到本地

[root@hadoop002 hadoop-2.7.2]# hadoop fs -copyToLocal /README.txt /

（10）-cp ：从HDFS的一个路径拷贝到HDFS的另一个路径

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

（11）-mv：在HDFS目录中移动文件

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/

（12）-get：等同于copyToLocal，就是从HDFS下载文件到本地

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./

（13）-getmerge：合并下载多个文件，比如HDFS的目录 /user/atguigu/test下有多个文件:log.1, log.2,log.3,...

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -getmerge /user/root/test/* ./zaiyiqi.txt

（14）-put：等同于copyFromLocal

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -put ./zaiyiqi.txt /user/root/test/

（15）-tail：显示一个文件的末尾

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -tail /sanguo/shuguo/kongming.txt

（16）-rm：删除文件或文件夹

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -rm /user/root/test/jinlian2.txt

（17）-rmdir：删除空目录

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -mkdir /test

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -rmdir /test

（18）-du统计文件夹的大小信息

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -du -s -h /user/root/test

[root@hadoop102 hadoop-2.7.2]$ hadoop fs -du  -h /user/root/test
1.3 K  /user/root/test/README.txt
15     /user/root/test/jinlian.txt
1.4 K  /user/root/test/zaiyiqi.txt

（19）-setrep：设置HDFS中文件的副本数量

[root@hadoop002 hadoop-2.7.2]# hadoop fs -setrep 2 /wgr/test/kongming.txt
Replication 2 set: /wgr/test/kongming.txt
[root@hadoop002 hadoop-2.7.2]#

 

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。