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。