Hadoop之HDFS的Shell操作

1、基本语法

　　bin/hadoop fs 具体命令 或者 bin/hdfs dfs 具体命令

　　dfs 是 fs 的实现类。

2、命令大全

[hadoop@hadoop102 hadoop-2.7.]$ bin/hadoop fs
Usage: hadoop fs [generic options]
    [-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] [-l] <localsrc> ... <dst>]
    [-copyToLocal [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
    [-count [-q] [-h] <path> ...]
    [-cp [-f] [-p | -p[topax]] <src> ... <dst>]
    [-createSnapshot <snapshotDir> [<snapshotName>]]
    [-deleteSnapshot <snapshotDir> <snapshotName>]
    [-df [-h] [<path> ...]]
    [-du [-s] [-h] <path> ...]
    [-expunge]
    [-find <path> ... <expression> ...]
    [-get [-p] [-ignoreCrc] [-crc] <src> ... <localdst>]
    [-getfacl [-R] <path>]
    [-getfattr [-R] {-n name | -d} [-e en] <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] [-l] <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>]]
    [-setfattr {-n name [-v value] | -x name} <path>]
    [-setrep [-R] [-w] <rep> <path> ...]
    [-stat [format] <path> ...]
    [-tail [-f] <file>]
    [-test -[defsz] <path>]
    [-text [-ignoreCrc] <src> ...]
    [-touchz <path> ...]
    [-truncate [-w] <length> <path> ...]
    [-usage [cmd ...]]

Generic options supported are
-conf <configuration file>     specify an application configuration file
-D <property=value>            use value for given property
-fs <local|namenode:port>      specify a namenode
-jt <local|resourcemanager:port>    specify a ResourceManager
-files <comma separated list of files>    specify comma separated files to be copied to the map reduce cluster
-libjars <comma separated list of jars>    specify comma separated jar files to include in the classpath.
-archives <comma separated list of archives>    specify comma separated archives to be unarchived on the compute machines.

The general command line syntax is
bin/hadoop command [genericOptions] [commandOptions]

3、常用命令操作

　　1）-help：输出这个命令参数

[hadoop@hadoop102 hadoop-2.7.]$ bin/hadoop fs -help rm

　　2）-ls：显示目录信息

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -ls /

　　3）-mkdir：在HDFS上创建目录

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -mkdir -p /sanguo/shuguo

　　4）-moveFromLocal：从本地剪切粘贴到HDFS

[hadoop@hadoop102 hadoop-2.7.]$ touch test.txt
[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs  -moveFromLocal  ./test.txt  /hadoop/test

　　5）-appendToFile：追加一个文件到已经存在到文件末尾

[hadoop@hadoop102 hadoop-2.7.]$ touch liubei.txt
[hadoop@hadoop102 hadoop-2.7.]$ vi liubei.txt
输入
san gu mao lu
[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo/kongming.txt

　　6）-cat：显示文件内容

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -cat /sanguo/shuguo/kongming.txt

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

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs  -chmod    /sanguo/shuguo/kongming.txt
[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs  -chown  atguigu:atguigu   /sanguo/shuguo/kongming.txt

　　注：hadoop文件系统中的文件并不能执行，因此没有执行权限。

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

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -copyFromLocal README.txt /

　　9）-copyToLocal：从HDFS拷贝到本地

[hadoop@hadoop102 hadoop-2.7.]$ 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@hadoop102 hadoop-2.7.]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

　　11）-mv：在HDFS目录中移动文件

[hadoop@hadoop102 hadoop-2.7.]$ 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@hadoop102 hadoop-2.7.]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./

　　13）-getmerge：合并下载多个文件，比如HDFS的目录 /user/hadoop/test 下有多个文件：log1，log2，log3...

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -getmerge /user/atguigu/test/* ./zaiyiqi.txt

　　14）-put：等同于 copyFromLocal

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -put ./zhangsan.txt /user/hadoop/test/

　　15）-tail：显示一个文件的末尾

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -tail /sanguo/shuguo/kongming.txt

　　16）-rm：删除文件或者文件夹

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -rm /user/hadoop/test/jinlian2.txt

[hadoop@hadoop102 hadoop-2.7.2]$ hadoop fs -rm -R /user/hadoop/test  #递归删除文件夹（无论文件夹下是否有文件都会删除）

　　17）-rmdir：删除空目录

[atguigu@hadoop102 hadoop-2.7.]$ hadoop fs -mkdir /test

　　18）-du：统计文件夹的大小信息

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

[atguigu@hadoop102 hadoop-2.7.]$ hadoop fs -du  -h /user/hadoop/test
1.3 K  /user/hadoop/test/README.txt
     /user/hadoop/test/jinlian.txt
1.4 K  /user/hadoop/test/zaiyiqi.txt

　　19）-setrep：设置HDFS中文件的副本数量

[hadoop@hadoop102 hadoop-2.7.]$ hadoop fs -setrep  /sanguo/shuguo/kongming.txt

注意：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，只有节点数增加到10台时，副本数才能达到10.