尚硅谷大数据技术之Hadoop(HDFS)第2章 HDFS的Shell操作(开发重点)

第2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

[atguigu@hadoop102 hadoop-2.7.2]$ 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)

[atguigu@hadoop102 hadoop-2.7.2]$ sbin/start-dfs.sh

[atguigu@hadoop103 hadoop-2.7.2]$ sbin/start-yarn.sh

(1)-help:输出这个命令参数

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -help rm

(2)-ls: 显示目录信息

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -ls /

(3)-mkdir:在HDFS上创建目录

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -mkdir -p /sanguo/shuguo

(4)-moveFromLocal:从本地剪切粘贴到HDFS

[atguigu@hadoop102 hadoop-2.7.2]$ touch kongming.txt

[atguigu@hadoop102 hadoop-2.7.2]$ 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

[atguigu@hadoop102 hadoop-2.7.2]$ touch liubei.txt

[atguigu@hadoop102 hadoop-2.7.2]$ vi liubei.txt

输入

san gu mao lu

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo/kongming.txt

(6)-cat:显示文件内容

[atguigu@hadoop102 hadoop-2.7.2]$ 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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs  -chmod  666  /sanguo/shuguo/kongming.txt

[atguigu@hadoop102 hadoop-2.7.2]$ 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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -copyFromLocal README.txt /

(9)-copyToLocal:从HDFS拷贝到本地

[atguigu@hadoop102 hadoop-2.7.2]$ 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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

(11)-mv:在HDFS目录中移动文件

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/

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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./

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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -getmerge /user/atguigu/test/* ./zaiyiqi.txt

(14)-put:等同于copyFromLocal

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -put ./zaiyiqi.txt /user/atguigu/test/

(15)-tail:显示一个文件的末尾

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -tail /sanguo/shuguo/kongming.txt

(16)-rm:删除文件或文件夹

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -rm /user/atguigu/test/jinlian2.txt

(17)-rmdir:删除空目录

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -mkdir /test

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -rmdir /test

(18)-du统计文件夹的大小信息

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -du -s -h /user/atguigu/test

2.7 K  /user/atguigu/test

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -du  -h /user/atguigu/test

1.3 K  /user/atguigu/test/README.txt

15     /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

[atguigu@hadoop102 hadoop-2.7.2]$ hadoop fs -setrep 10 /sanguo/shuguo/kongming.txt

                                                                     图3-3  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。


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