HDFS概述和Shell操作

时间:2022-01-06 21:57:09

大数据技术之Hadoop(HDFS)

第一章 HDFS概述

HDFS组成架构

HDFS概述和Shell操作

HDFS概述和Shell操作

HDFS文件块大小

HDFS概述和Shell操作

HDFS概述和Shell操作

第二章 HDFS的Shell操作(开发重点

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

$ 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 ...]]

3.常用命令实操

(0)启动Hadoop集群(方便后续的测试)

$ sbin/start-dfs.sh
$ sbin/start-yarn.sh

(1)-help:输出这个命令参数

$ hadoop fs -help rm

(2)-ls: 显示目录信息

$ hadoop fs -ls /

(3)-mkdir:在HDFS上创建目录

$ hadoop fs -mkdir -p /sanguo/shuguo

(4)-moveFromLocal:从本地剪切粘贴到HDFS

$ touch kongming.txt

$ hadoop fs  -moveFromLocal  ./kongming.txt  /sanguo/shuguo

(5)-appendToFile:追加一个文件到已经存在的文件末尾

$ touch liubei.txt
$ vi liubei.txt
输入
san gu mao lu
$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo/kongming.txt

(6)-cat:显示文件内容

$ 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

$ hadoop fs  -chmod    /sanguo/shuguo/kongming.txt
$ hadoop fs -chown atguigu:atguigu /sanguo/shuguo/kongming.txt

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

$ hadoop fs -copyFromLocal README.txt /

(9)-copyToLocal:从HDFS拷贝到本地

$ 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

$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

(11)-mv:在HDFS目录中移动文件

$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/

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

$ 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,...

$ hadoop fs -getmerge /user/atguigu/test/* ./zaiyiqi.txt

(14)-put:等同于copyFromLocal

$ hadoop fs -put ./zaiyiqi.txt /user/atguigu/test/

(15)-tail:显示一个文件的末尾

$ hadoop fs -tail /sanguo/shuguo/kongming.txt

(16)-rm:删除文件或文件夹

$ hadoop fs -rm /user/atguigu/test/jinlian2.txt

(17)-rmdir:删除空目录

$ hadoop fs -mkdir /test
$ hadoop fs -rmdir /test

(18)-du统计文件夹的大小信息

$ hadoop fs -du -s -h /user/atguigu/test
2.7 K /user/atguigu/test $ hadoop fs -du -h /user/atguigu/test 1.3 K /user/atguigu/test/README.txt
/user/atguigu/test/jinlian.txt
1.4 K /user/atguigu/test/zaiyiqi.txt

(19)-setrep:设置HDFS中文件的副本数量

$ hadoop fs -setrep  /sanguo/shuguo/kongming.txt

HDFS概述和Shell操作

                    图  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。