Most of the HDFS commands just like the same commands in linux, such as cat,chgrp,chmod,chown,cp,df,du,find,ls,mkdir,mv,rm,rmdir,stat, while also provide some other enhanced commands:
Common commands
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| [root@hadoop001 ~]# hdfs dfs -ls /
[root@hadoop001 ~]# hdfs dfs -put hello /
[root@hadoop001 ~]# hdfs dfs -ls /
Found 1 items
-rw-r--r-- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -get /hello h1
[root@hadoop001 ~]# ll
total 2043328
-rw-r--r-- 1 root root 12 May 2 14:21 h1
-rw-r--r-- 1 root root 12 May 2 14:19 hello
[root@hadoop001 ~]# cat h1
hello world
[root@hadoop001 ~]# hdfs dfs -chmod a+w /hello
[root@hadoop001 ~]# hdfs dfs -ls /
Found 1 items
-rw-rw-rw- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -chmod a-w /hello
[root@hadoop001 ~]# hdfs dfs -ls /
Found 1 items
-r--r--r-- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -chmod o+w /hello
[root@hadoop001 ~]# hdfs dfs -ls /
22/05/02 14:24:10 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Found 1 items
-r--r--rw- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -df /
Filesystem Size Used Available Use%
hdfs://ns 127219077120 106496 94618918912 0%
[root@hadoop001 ~]# hdfs dfs -df -h /
Filesystem Size Used Available Use%
hdfs://ns 118.5 G 104 K 88.1 G 0%
[root@hadoop001 ~]# hdfs dfs -du -h /
12 /hello
[root@hadoop001 ~]# hdfs dfs -mkdir /dir1
[root@hadoop001 ~]# hdfs dfs -mkdir -p /dir2/dir22/dir222
[root@hadoop001 ~]# hdfs dfs -find /
/
/dir1
/dir2
/dir2/dir22
/dir2/dir22/dir222
/hello
[root@hadoop001 ~]# hdfs dfs -ls -R /
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir1
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2/dir22
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2/dir22/dir222
-r--r--rw- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -du /
0 /dir1
0 /dir2
12 /hello
[root@hadoop001 ~]# hdfs dfs -cp /hello /dir2/dir22
[root@hadoop001 ~]# hdfs dfs -ls -R /
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir1
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2
drwxr-xr-x - root supergroup 0 2022-05-02 14:27 /dir2/dir22
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2/dir22/dir222
-rw-r--r-- 3 root supergroup 12 2022-05-02 14:27 /dir2/dir22/hello
-r--r--rw- 3 root supergroup 12 2022-05-02 14:20 /hello
[root@hadoop001 ~]# hdfs dfs -mv /hello /dir1
[root@hadoop001 ~]# hdfs dfs -ls -R /
drwxr-xr-x - root supergroup 0 2022-05-02 14:28 /dir1
-r--r--rw- 3 root supergroup 12 2022-05-02 14:20 /dir1/hello
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2
drwxr-xr-x - root supergroup 0 2022-05-02 14:27 /dir2/dir22
drwxr-xr-x - root supergroup 0 2022-05-02 14:26 /dir2/dir22/dir222
-rw-r--r-- 3 root supergroup 12 2022-05-02 14:27 /dir2/dir22/hello
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Enhanced commands
appendToFile
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| [root@hadoop001 ~]# echo "hello, guys" > guys
[root@hadoop001 ~]# hdfs dfs -appendToFile guys /dir1/hello
[root@hadoop001 ~]# hdfs dfs -cat /dir1/hello
hello world
hello, guys
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createSnapshot
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| [root@hadoop001 ~]# hdfs dfs -createSnapshot /dir1
createSnapshot: Directory is not a snapshottable directory: /dir1
[root@hadoop001 ~]# hdfs dfsadmin -allowSnapshot /dir1
Allowing snaphot on /dir1 succeeded
[root@hadoop001 ~]# hdfs dfs -createSnapshot /dir1
Created snapshot /dir1/.snapshot/s20220502-144142.019
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lsSnapshottableDir
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| [root@hadoop001 ~]# hdfs lsSnapshottableDir
drwxr-xr-x 0 root supergroup 0 2022-05-02 14:41 1 65536 /dir1
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deleteSnapshot
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| [root@hadoop001 ~]# hdfs dfs -deleteSnapshot /dir1 s20220502-144142.019
[root@hadoop001 ~]# hdfs dfs -ls -R /dir1/.snapshot/
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moveFrom local
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| [root@hadoop001 ~]# ll
total 16
-rw-r--r-- 1 root root 12 May 2 14:32 guys
-rw-r--r-- 1 root root 12 May 2 14:21 h1
-rw-r--r-- 1 root root 12 May 2 14:19 hello
drwxr-xr-x 3 root root 4096 May 2 14:32 tmp
[root@hadoop001 ~]#
[root@hadoop001 ~]# hdfs dfs -moveFromLocal hello /
[root@hadoop001 ~]# ll
total 12
-rw-r--r-- 1 root root 12 May 2 14:32 guys
-rw-r--r-- 1 root root 12 May 2 14:21 h1
drwxr-xr-x 3 root root 4096 May 2 14:32 tmp
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