// todo
第2章 HDFS的Shell操作（开发重点）
2.1 基本语法
hadoop fs 具体命令 OR hdfs dfs 具体命令
两个是完全相同的。
2.2 命令大全
[atguigu@hadoop102 hadoop-3.1.3]$ bin/hadoop fs

[-appendToFile … ]
[-cat [-ignoreCrc] …]
[-chgrp [-R] GROUP PATH…]
[-chmod [-R] <MODE[,MODE]… | OCTALMODE> PATH…]
[-chown [-R] [OWNER][:[GROUP]] PATH…]
[-copyFromLocal [-f] [-p] … ]
[-copyToLocal [-p] [-ignoreCrc] [-crc] … ]
[-count [-q] …]
[-cp [-f] [-p] … ]
[-df [-h] [ …]]
[-du [-s] [-h] …]
[-get [-p] [-ignoreCrc] [-crc] … ]
[-getmerge [-nl] ]
[-help [cmd …]]
[-ls [-d] [-h] [-R] [ …]]
[-mkdir [-p] …]
[-moveFromLocal … ]
[-moveToLocal ]
[-mv … ]
[-put [-f] [-p] … ]
[-rm [-f] [-r|-R] [-skipTrash] …]
[-rmdir [–ignore-fail-on-non-empty]

[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -moveFromLocal ./shuguo.txt /sanguo
2）-copyFromLocal：从本地文件系统中拷贝文件到HDFS路径去
[atguigu@hadoop102 hadoop-3.1.3]$ vim weiguo.txt
输入：
weiguo

[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -copyFromLocal weiguo.txt /sanguo
3）-put：等同于copyFromLocal，生产环境更习惯用put
[atguigu@hadoop102 hadoop-3.1.3]$ vim wuguo.txt
输入：
wuguo

[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -put ./wuguo.txt /sanguo
4）-appendToFile：追加一个文件到已经存在的文件末尾
[atguigu@hadoop102 hadoop-3.1.3]$ vim liubei.txt
输入：
liubei

[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo.txt
2.3.3 下载
1）-copyToLocal：从HDFS拷贝到本地
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -copyToLocal /sanguo/shuguo.txt ./
2）-get：等同于copyToLocal，生产环境更习惯用get
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -get /sanguo/shuguo.txt ./shuguo2.txt
2.3.4 HDFS直接操作
1）-ls: 显示目录信息
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -ls /sanguo
2）-cat：显示文件内容
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -cat /sanguo/shuguo.txt
3）-chgrp、-chmod、-chown：Linux文件系统中的用法一样，修改文件所属权限
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -chmod 666 /sanguo/shuguo.txt
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -chown atguigu:atguigu /sanguo/shuguo.txt
4）-mkdir：创建路径
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -mkdir /jinguo
5）-cp：从HDFS的一个路径拷贝到HDFS的另一个路径
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -cp /sanguo/shuguo.txt /jinguo
6）-mv：在HDFS目录中移动文件
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -mv /sanguo/wuguo.txt /jinguo
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -mv /sanguo/weiguo.txt /jinguo
7）-tail：显示一个文件的末尾1kb的数据
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -tail /jinguo/shuguo.txt
8）-rm：删除文件或文件夹
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -rm /sanguo/shuguo.txt
9）-rm -r：递归删除目录及目录里面内容
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -rm -r /sanguo
10）-du统计文件夹的大小信息
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -du -s -h /jinguo
27 81 /jinguo

[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -du -h /jinguo
14 42 /jinguo/shuguo.txt
7 21 /jinguo/weiguo.txt
6 18 /jinguo/wuguo.tx
说明：27表示文件大小；81表示27*3个副本；/jinguo表示查看的目录
11）-setrep：设置HDFS中文件的副本数量
[atguigu@hadoop102 hadoop-3.1.3]$ hadoop fs -setrep 10 /jinguo/shuguo.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。