1、基本語法

　　bin/hadoop fs 具體命令 或者 bin/hdfs dfs 具體命令

　　dfs 是 fs 的實現類。

2、命令大全

[[email protected] hadoop-2.7.2]$ 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：輸出這個命令引數

[[email protected] hadoop-2.7.2]$ bin/hadoop fs -help rm

　　2）-ls：顯示目錄資訊

[[email protected] hadoop-2.7.2]$ hadoop fs -ls /

　　3）-mkdir：在HDFS上建立目錄

[[email protected] hadoop-2.7.2]$ hadoop fs -mkdir -p /sanguo/shuguo

　　4）-moveFromLocal：從本地剪下貼上到HDFS

[[email protected] hadoop-2.7.2]$ touch test.txt
[[email protected] hadoop-2.7.2]$ hadoop fs  -moveFromLocal  ./test.txt  /hadoop/test

　　5）-appendToFile：追加一個檔案到已經存在到檔案末尾

[[email protected] hadoop-2.7.2]$ touch liubei.txt
[[email protected] hadoop-2.7.2]$ vi liubei.txt
輸入
san gu mao lu
[[email protected] hadoop-2.7.2]$ hadoop fs -appendToFile liubei.txt /sanguo/shuguo/kongming.txt

　　6）-cat：顯示檔案內容

[[email protected] hadoop-2.7.2]$ hadoop fs -cat /sanguo/shuguo/kongming.txt

　　7）-chgrp、-chmod、-chown：同Linux檔案系統中的用法一樣，修改檔案所屬許可權

[[email protected] hadoop-2.7.2]$ hadoop fs  -chmod  666  /sanguo/shuguo/kongming.txt
[[email protected] hadoop-2.7.2]$ hadoop fs  -chown  atguigu:atguigu   /sanguo/shuguo/kongming.txt

　　注：hadoop檔案系統中的檔案並不能執行，因此沒有執行許可權。

　　8）-copyFromLocal：從本地檔案系統中拷貝檔案到HDFS路徑中去

[[email protected] hadoop-2.7.2]$ hadoop fs -copyFromLocal README.txt /

　　9）-copyToLocal：從HDFS拷貝到本地

[[email protected] hadoop-2.7.2]$ hadoop fs -copyToLocal /sanguo/shuguo/kongming.txt ./

　　10）-cp：從HDFS的一個路徑拷貝到HDFS的另一個路徑

[[email protected] hadoop-2.7.2]$ hadoop fs -cp /sanguo/shuguo/kongming.txt /zhuge.txt

　　11）-mv：在HDFS目錄中移動檔案

[[email protected] hadoop-2.7.2]$ hadoop fs -mv /zhuge.txt /sanguo/shuguo/

　　12）-get：等同於copyToLocal，就是從HDFS下載檔案到本地

[[email protected] hadoop-2.7.2]$ hadoop fs -get /sanguo/shuguo/kongming.txt ./

　　13）-getmerge：合併下載多個檔案，比如HDFS的目錄 /user/hadoop/test 下有多個檔案：log1，log2，log3...

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

　　14）-put：等同於 copyFromLocal

[[email protected] hadoop-2.7.2]$ hadoop fs -put ./zhangsan.txt /user/hadoop/test/

　　15）-tail：顯示一個檔案的末尾

[[email protected] hadoop-2.7.2]$ hadoop fs -tail /sanguo/shuguo/kongming.txt

　　16）-rm：刪除檔案或者資料夾

[[email protected] hadoop-2.7.2]$ hadoop fs -rm /user/hadoop/test/jinlian2.txt

[[email protected] hadoop-2.7.2]$ hadoop fs -rm -R /user/hadoop/test  #遞迴刪除資料夾（無論資料夾下是否有檔案都會刪除）

　　17）-rmdir：刪除空目錄

[[email protected] hadoop-2.7.2]$ hadoop fs -mkdir /test

　　18）-du：統計資料夾的大小資訊

[[email protected] hadoop-2.7.2]$ hadoop fs -du -s -h /user/hadoop/test
2.7 K  /user/hadoop/test

[[email protected] hadoop-2.7.2]$ hadoop fs -du  -h /user/hadoop/test
1.3 K  /user/hadoop/test/README.txt
15     /user/hadoop/test/jinlian.txt
1.4 K  /user/hadoop/test/zaiyiqi.txt

　　19）-setrep：設定HDFS中檔案的副本數量

[[email protected] hadoop-2.7.2]$ hadoop fs -setrep 10 /sanguo/shuguo/kongming.txt

   注意：這裡設定的副本數只是記錄在NameNode 的元資料中，是否真的會有這麼多副本，還得看 DataNode 的數量。因為目前只有3臺裝置，最多也就3個副本，只有節點數增加到10臺時，副本數才能達到10.