第2章 HDFS的Shell操作
1.基本语法
bin/hadoop fs 具体命令
bin/hdfs dfs 具体命令
dfs是fs的实现类。
2.命令大全
[zhangyong@hadoop101 hadoop-3.1.2]$ bin/hadoop fs
3.常用命令实操
(0)启动Hadoop集群(方便后续的测试)
[zhangyong@hadoop101 hadoop-3.1.2]$ sbin/start-dfs.sh 启动dsf
[zhangyong@hadoop102 hadoop-3.1.2]$ sbin/start-yarn.sh 启动yarn
[zhangyong@hadoop103 hadoop-3.1.2]$ mr-jobhistory-daemon.sh start historyserver 启动历史服务器
启动是否成功查看jps:
显示上述服务表示启动成功:
网页验证是否启动成功:
http://hadoop101:9870/dfshealth.html#tab-datanode
(1)-help:输出这个命令参数
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -help rm
(2)-ls: 显示目录信息
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -ls /
(3)-mkdir:在HDFS上创建目录
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -mkdir -p /sanguo/shuguo
(4)-moveFromLocal:从本地剪切粘贴到HDFS
[zhangyong@hadoop101 hadoop-3.1.2]$ touch kongming.txt //在本地创建kongming.txt
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -moveFromLocal ./kongming.txt /sanguo/shuguo //将本地的kongming.txt提交到fds中
(5)-appendToFile:追加一个文件到已经存在的文件末尾
[zhangyong@hadoop101 hadoop-3.1.2]$ touch zhangyong.txt
[zhangyong@hadoop101 hadoop-3.1.2]$ vi zhangyong.txt
输入
zhangyong cainiao
[zhangyong@hadoop101 hadoop-3.1.2]$hdfs dfs -appendToFile zhangyong.txt /sanguo/shuguo/kongming.txt
(6)-cat:显示文件内容
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -cat /sanguo/shuguo/kongming.txt
(7)-chgrp 、-chmod、-chown:Linux文件系统中的用法一样,修改文件所属权限
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -chmod 666 /sanguo/shuguo/kongming.txt
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -chown zhangyong:zhangyong /sanguo/shuguo/kongming.txt
(8)-copyFromLocal:从本地文件系统中拷贝文件到HDFS路径去
[zhangyong@hadoop101 hadoop-3.1.2]$ hdfs dfs -copyFromLocal README.txt /
(9)-copyToLocal:从HDFS拷贝到本地
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -copyToLocal /sanguo/shuguo/kongming.txt ./
(10)-cp :从HDFS的一个路径拷贝到HDFS的另一个路径
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt
(11)-mv:在HDFS目录中移动文件
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/
(12)-get:等同于copyToLocal,就是从HDFS下载文件到本地
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./
(13)-getmerge:合并下载多个文件,比如HDFS的目录 /user/zhangyong/test下有多个文件:log.1, log.2,log.3,…
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -getmerge /user/zhangyong/test/* ./zaiyiqi.txt
(14)-put:等同于copyFromLocal
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -put ./zaiyiqi.txt /user/zhangyong/test/
(15)-tail:显示一个文件的末尾
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -tail /sanguo/shuguo/kongming.txt
(16)-rm:删除文件或文件夹
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -rm /sanguo/shuguo/zhuge.txt
(17)-rmdir:删除空目录
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -mkdir /test 创建空目录
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -rmdir /test 删除目录
(18)-du统计文件夹的大小信息
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -du -s -h /user/zhangyong/test
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -du -h /user/zhangyong/test
(19)-setrep:设置HDFS中文件的副本数量
[zhangyong@hadoop101 hadoop-3.1.2]$ hadoop fs -setrep 10 /sanguo/shuguo/kongming.txt
HDFS副本数量
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。