Hadoop-HDFS-常用命令与shell操作-连载中

第二章 HDFS的Shell操作

2.1 基本语法

hadoop fs 命令 和 hdfs dfs 命令，两个是完全相同的。

2.2 命令大全

[qinjl@hadoop102 hadoop-3.1.3]$ bin/hadoop fs

[-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] <localsrc> ... <dst>]
        [-copyToLocal [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
        [-count [-q] <path> ...]
        [-cp [-f] [-p] <src> ... <dst>]
        [-createSnapshot <snapshotDir> [<snapshotName>]]
        [-deleteSnapshot <snapshotDir> <snapshotName>]
        [-df [-h] [<path> ...]]
        [-du [-s] [-h] <path> ...]
        [-expunge]
        [-get [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
        [-getfacl [-R] <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] <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>]]
        [-setrep [-R] [-w] <rep> <path> ...]
        [-stat [format] <path> ...]
        [-tail [-f] <file>]
        [-test -[defsz] <path>]
        [-text [-ignoreCrc] <src> ...]
        [-touchz <path> ...]
        [-usage [cmd ...]]

2.3 常用命令实操

2.3.1 准备工作

1）启动Hadoop集群（方便后续的测试）

[qinjl@hadoop102 hadoop-3.1.3]$ sbin/start-dfs.sh
[qinjl@hadoop103 hadoop-3.1.3]$ sbin/start-yarn.sh

2）-help：输出这个命令参数

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -help rm

2.3.2 上传

1）-moveFromLocal：从本地剪切粘贴到HDFS

[qinjl@hadoop102 hadoop-3.1.3]$ touch kongming.txt
[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs  -moveFromLocal ./kongming.txt /sanguo/shuguo

2）-copyFromLocal：从本地文件系统中拷贝文件到HDFS路径去

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -copyFromLocal README.txt /

3）-appendToFile：追加一个文件到已经存在的文件末尾

[qinjl@hadoop102 hadoop-3.1.3]$ touch liubei.txt
[qinjl@hadoop102 hadoop-3.1.3]$ vi liubei.txt
输入
san gu mao lu
[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo/kongming.txt

4）-put：等同于copyFromLocal

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -put ./liubei.txt /user/qinjl/test/

2.3.3 下载

1）-copyToLocal：从HDFS拷贝到本地

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -copyToLocal /sanguo/shuguo/kongming.txt ./

2）-get：等同于copyToLocal，就是从HDFS下载文件到本地

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./

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

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -getmerge /user/qinjl/test/* ./zaiyiqi.txt

2.3.4 HDFS直接操作

1）-ls: 显示目录信息

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -ls /

2）-mkdir：在HDFS上创建目录

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -mkdir -p /sanguo/shuguo

3）-cat：显示文件内容

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -cat /sanguo/shuguo/kongming.txt

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

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -chmod 666 /sanguo/shuguo/kongming.txt
[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -chown qinjl:qinjl /sanguo/shuguo/kongming.txt

5）-cp ：从HDFS的一个路径拷贝到HDFS的另一个路径（会自动更改文件权限，变成默认创建时权限）

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

6）-mv：在HDFS目录中移动文件

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/

7）-tail：显示一个文件的末尾1kb的数据

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -tail /sanguo/shuguo/kongming.txt

8）-rm：删除文件或文件夹

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -rm /user/qinjl/test/jinlian2.txt

9）-rmdir：删除空目录

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -mkdir /test
[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -rmdir /test

10）-du统计文件夹的大小信息

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -du -s -h /user/qinjl/test
2.7 K  /user/qinjl/test

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -du  -h /user/qinjl/test
1.3 K  /user/qinjl/test/README.txt
15     /user/qinjl/test/jinlian.txt
1.4 K  /user/qinjl/test/zaiyiqi.txt

11）-setrep：设置HDFS中文件的副本数量

[qinjl@hadoop102 hadoop-3.1.3]$ hadoop fs -setrep 10 /sanguo/shuguo/kongming.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。