HDFS命令行操作

启动后可通过命令行使用hadoop。

(1)所有命令 （先将$HADOOP_HOME/bin加入到.bashrc的$PATH变量中）

 [hadoop@node14 hadoop-0.21.0]$ ll $HADOOP_HOME/bin
 total 88
 -rwxr-xr-x 1 hadoop hadoop 4131 Aug 17  2010 hadoop
 -rwxr-xr-x 1 hadoop hadoop 8658 Aug 17  2010 hadoop-config.sh
 -rwxr-xr-x 1 hadoop hadoop 3841 Aug 17  2010 hadoop-daemon.sh
 -rwxr-xr-x 1 hadoop hadoop 1242 Aug 17  2010 hadoop-daemons.sh
 -rwxr-xr-x 1 hadoop hadoop 4130 Aug 17  2010 hdfs
 -rwxr-xr-x 1 hadoop hadoop 1201 Aug 17  2010 hdfs-config.sh
 -rwxr-xr-x 1 hadoop hadoop 3387 Aug 17  2010 mapred
 -rwxr-xr-x 1 hadoop hadoop 1207 Aug 17  2010 mapred-config.sh
 -rwxr-xr-x 1 hadoop hadoop 2720 Aug 17  2010 rcc
 -rwxr-xr-x 1 hadoop hadoop 2058 Aug 17  2010 slaves.sh
 -rwxr-xr-x 1 hadoop hadoop 1367 Aug 17  2010 start-all.sh
 -rwxr-xr-x 1 hadoop hadoop 1018 Aug 17  2010 start-balancer.sh
 -rwxr-xr-x 1 hadoop hadoop 1778 Aug 17  2010 start-dfs.sh
 -rwxr-xr-x 1 hadoop hadoop 1255 Aug 17  2010 start-mapred.sh
 -rwxr-xr-x 1 hadoop hadoop 1359 Aug 17  2010 stop-all.sh
 -rwxr-xr-x 1 hadoop hadoop 1069 Aug 17  2010 stop-balancer.sh
 -rwxr-xr-x 1 hadoop hadoop 1277 Aug 17  2010 stop-dfs.sh
 -rwxr-xr-x 1 hadoop hadoop 1163 Aug 17  2010 stop-mapred.sh

(2) hadoop命令

 [hadoop@node14 hadoop-0.21.0]$ hadoop
 Usage: hadoop [--config confdir] COMMAND
        where COMMAND is one of:
   fs                   run a generic filesystem user client
   version              print the version
   jar <jar>            run a jar file
   distcp <srcurl> <desturl> copy file or directories recursively
   archive -archiveName NAME -p <parent path> <src>* <dest> create a hadoop archive
   classpath            prints the class path needed to get the
                        Hadoop jar and the required libraries
   daemonlog            get/set the log level for each daemon
  or
   CLASSNAME            run the class named CLASSNAME

 Most commands print help when invoked w/o parameters.

(3) hadoop fs 

 [hadoop@node14 hadoop-0.21.0]$ hadoop fs
 Usage: java FsShell
            [-ls <path>]
            [-lsr <path>]
            [-df [<path>]]
            [-du [-s] [-h] <path>]
            [-dus <path>]
            [-count[-q] <path>]
            [-mv <src> <dst>]
            [-cp <src> <dst>]
            [-rm [-skipTrash] <path>]
            [-rmr [-skipTrash] <path>]
            [-expunge]
            [-put <localsrc> ... <dst>]
            [-copyFromLocal <localsrc> ... <dst>]
            [-moveFromLocal <localsrc> ... <dst>]
            [-get [-ignoreCrc] [-crc] <src> <localdst>]
            [-getmerge <src> <localdst> [addnl]]
            [-cat <src>]
            [-text <src>]
            [-copyToLocal [-ignoreCrc] [-crc] <src> <localdst>]
            [-moveToLocal [-crc] <src> <localdst>]
            [-mkdir <path>]
            [-setrep [-R] [-w] <rep> <path/file>]
            [-touchz <path>]
            [-test -[ezd] <path>]
            [-stat [format] <path>]
            [-tail [-f] <file>]
            [-chmod [-R] <MODE[,MODE]... | OCTALMODE> PATH...]
            [-chown [-R] [OWNER][:[GROUP]] PATH...]
            [-chgrp [-R] GROUP PATH...]
            [-help [cmd]]

 Generic options supported are
 -conf <configuration file>     specify an application configuration file
 -D <propertyproperty=value>            use value for given property
 -fs <local|namenode:port>      specify a namenode
 -jt <local|jobtracker:port>    specify a job tracker
 -files <comma separated list of files>    specify comma separated files to be co                                                                                                                     pied 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]

(4)HDFS操作

 hadoop fs
 hadoop fs -ls
 hadoop fs -mkdir firstdir<span style="white-space:pre">         </span>//HDFS创建目录
 hadoop fs -rmr firstdir<span style="white-space:pre">               </span>//HDFS删除目录
 hadoop fs -put test.txt first.txt<span style="white-space:pre">     </span>//从本地目录中将文件放入HDFS
 hadoop fs  -cat first.txt
 hadoop fs  -df
 hadoop fs -get first.txt FirstTXTfromHDFS.txt    //从HDFS取文件到本地

若文件写入遇到异常

(0)检查和机器名是否正确
node14配置了外部IP和内部IP，在/etc/hosts中加入两条IP与机器名的对应表，如果外部IP放在内部IP的前面，
则通过netstat -npl查看时，发现9000和9001是外部IP占据，故应在/etc/hosts中内部IP放在外部的IP的前面。
或者在conf中配置文件中，全部用IP，而不要用机器名。


(1)关闭防火墙
sudo /etc/init.d/iptables stop


(2)查看磁盘空间是否正常
df -hl


(3)检查目录是否正常
hadoop.tmp.dir默认：/tmp/hadoop-${user.name}
删除/tmp下面的文件，重新hadoop namenode -format,重启所有进程。


(4)单独启动各个进程
在namenode和datanode上分别启动节点
$hadoop-daemon.sh start namenode
$hadoop-daemon.sh start datanode