概述
所有的hadoop命令都是有 bin/hadoop调用执行的，执行hadoop脚本没有任何参数的时候他会输出所有命令的描述信息。
用法：hadoop [--config confdir] [COMMAND] [GENERIC_OPTIONS] [COMMAND_OPTIONS]
hadoop有个输入选项解析框架可以利用在运行class的时候来解析参数
通用选项
dfsadmin, fs, fsck, job and fetchdt都支持下属选项所有的。应用程序需要实现Tool接口然后才能支持通用选项解析。
| -conf <configuration file> | Specify an application configuration file. |
| -D <property>=<value> | Use value for given property. |
| -jt <local> or <jobtracker:port> | Specify a job tracker. Applies only to job. |
| -files <comma separated list of files> | Specify comma separated files to be copied to the map reduce cluster. Applies only to job. |
| -libjars <comma seperated list of jars> | Specify comma separated jar files to include in the classpath. Applies only to job. |
| -archives <comma separated list of archives> | Specify comma separated archives to be unarchived on the compute machines. Applies only to job. |
用户命令
hadoop集群用户基于命令是非常方便的。
archive：
创建一个hadoop归档，更多信息可以在hadoop归档中查找。
用法：hadoop archive -archiveName NAME <src>* <dest>
| -archiveName NAME | Name of the archive to be created. |
| src | Filesystem pathnames which work as usual with regular expressions. |
| dest | Destination directory which would contain the archive. |
distcp：
循环拷贝文件和目录，详情可以在hadoop的DistCp 指南中查看。
用法：hadoop distcp <srcurl> <desturl>
| srcurl | Source Url |
| desturl | Destination Url |
fs:
用法：hadoop fs [GENERIC_OPTIONS] [COMMAND_OPTIONS]
不赞成使用，已经被dfs和hdfs替代
运行一个文件系统的客户端，COMMAND_OPTIONS 变量的值可以参考文件系统shell指南
fsck：
运行一个hdfs系统检查工具更多信息参考fsck
用法：hadoop fsck [GENERIC_OPTIONS] <path> [-move | -delete | -openforwrite] [-files [-blocks [-locations | -racks]]]
| path | Start checking from this path. |
| -move | Move corrupted files to /lost+found |
| -delete | Delete corrupted files. |
| -openforwrite | Print out files opened for write. |
| -files | Print out files being checked. |
| -blocks | Print out block report. |
| -locations | Print out locations for every block. |
| -racks | Print out network topology for data-node locations. |
fetchdt：
从namenode上获取标示字符串，更多信息参考fetchdt
用法：hadoop fetchdt [GENERIC_OPTIONS] [--webservice <namenode_http_addr>] <path>
| fileName | File name to store the token into. |
| --webservice https_address | use http protocol instead of RPC |
jar：
运行一个jar文件，用户可以在此jar中实现具体的Map Reduce 业务
用法：hadoop jar <jar> [mainClass] args...
streaming job也可以通过此方式执行，详情可以参考流应用例子，同时wordcount例子也是这样的方式，也可以参考
job：
此命令可以跟Map Reduce的job交互
用法：
hadoop job [GENERIC_OPTIONS] [-submit <job-file>] | [-status <job-id>] | [-counter <job-id> <group-name> <counter-name>] | [-kill <job-id>] | [-events <job-id> <from-event-#> <#-of-events>] | [-history [all] <jobOutputDir>] | [-list [all]] | [-kill-task <task-id>] | [-fail-task <task-id>] | [-set-priority <job-id> <priority>]
| -submit job-file | Submits the job. |
| -status job-id | Prints the map and reduce completion percentage and all job counters. |
| -counter job-id group-namecounter-name | Prints the counter value. |
| -kill job-id | Kills the job. |
| -events job-id from-event-##-of-events | Prints the events' details received by jobtracker for the given range. |
| -history [all]jobOutputDir | Prints job details, failed and killed tip details. More details about the job such as successful tasks and task attempts made for each task can be viewed by specifying the [all] option. |
| -list [all] | Displays jobs which are yet to complete. -list all displays all jobs. |
| -kill-task task-id | Kills the task. Killed tasks are NOT counted against failed attempts. |
| -fail-task task-id | Fails the task. Failed tasks are counted against failed attempts. |
| -set-priority job-id priority | Changes the priority of the job. Allowed priority values are VERY_HIGH, HIGH, NORMAL, LOW, VERY_LOW |
pipes:
运行pipes任务用法如下：
hadoop pipes [-conf <path>] [-jobconf <key=value>, <key=value>, ...] [-input <path>] [-output <path>] [-jar <jar file>] [-inputformat <class>] [-map <class>] [-partitioner <class>] [-reduce <class>] [-writer <class>] [-program <executable>] [-reduces <num>]
| -conf path | Configuration for job |
| -jobconf key=value, key=value, ... | Add/override configuration for job |
| -input path | Input directory |
| -output path | Output directory |
| -jar jar file | Jar filename |
| -inputformat class | InputFormat class |
| -map class | Java Map class |
| -partitioner class | Java Partitioner |
| -reduce class | Java Reduce class |
| -writer class | Java RecordWriter |
| -program executable | Executable URI |
| -reduces num | Number of reduces |
queue:
此命令可以跟hadoop job的队列交互
用法：
hadoop queue [-list] | [-info <job-queue-name> [-showJobs]] | [-showacls]
| -list | Gets list of Job Queues configured in the system. Along with scheduling information associated with the job queues. |
| -info job-queue-name [-showJobs] | Displays the job queue information and associated scheduling information of particular job queue. If -showJobs options is present a list of jobs submitted to the particular job queue is displayed. |
| -showacls | Displays the queue name and associated queue operations allowed for the current user. The list consists of only those queues to which the user has access. |
version：
输出hadoop的版本信息，使用方式如下：
hadoop version
CLASSNAME：
hadoop脚本可以执行任意类，用法如下：
hadoop CLASSNAME运行classname的那个类
classpath：
输出依赖lib，用法如下：
hadoop classpath
管理员命令
hadoop集群管理员可以基于管理员命令很好的管理集群
balancer：
运行一个集群均衡工具管理员可以执行 Ctrl-C去停止这个操作，用法如下：
hadoop balancer [-threshold <threshold>]
| Description | |
| -threshold threshold | Percentage of disk capacity. This overwrites the default threshold. |
daemonlog：
为每个守护进程设置或查看日志级别，用法如下：
hadoop daemonlog -getlevel <host:port> <name> Usage: hadoop daemonlog -setlevel <host:port> <name> <level>
| -getlevel host:port name | Prints the log level of the daemon running at host:port. This command internally connects to http://host:port/logLevel?log=name |
| -setlevel host:port name level | Sets the log level of the daemon running at host:port. This command internally connects to http://host:port/logLevel?log=name |
datanode：
启动一个datanode，用法如下：
hadoop datanode [-rollback]
| -rollback | Rollsback the datanode to the previous version. This should be used after stopping the datanode and distributing the old hadoop version. |
dfsadmin ：
启动一个hdfs 管理客户端，用法如下：
hadoop dfsadmin [GENERIC_OPTIONS] [-report] [-safemode enter | leave | get | wait] [-refreshNodes] [-finalizeUpgrade] [-upgradeProgress status | details | force] [-metasave filename] [-setQuota <quota> <dirname>...<dirname>] [-clrQuota <dirname>...<dirname>] [-restoreFailedStorage true|false|check] [-help [cmd]]
| -report | Reports basic filesystem information and statistics. |
| -safemode enter / leave / get / wait | Safe mode maintenance command. Safe mode is a Namenode state in which it 1. does not accept changes to the name space (read-only) 2. does not replicate or delete blocks. Safe mode is entered automatically at Namenode startup, and leaves safe mode automatically when the configured minimum percentage of blocks satisfies the minimum replication condition. Safe mode can also be entered manually, but then it can only be turned off manually as well. |
| -refreshNodes | Re-read the hosts and exclude files to update the set of Datanodes that are allowed to connect to the Namenode and those that should be decommissioned or recommissioned. |
| -finalizeUpgrade | Finalize upgrade of HDFS. Datanodes delete their previous version working directories, followed by Namenode doing the same. This completes the upgrade process. |
| -upgradeProgress status / details / force | Request current distributed upgrade status, a detailed status or force the upgrade to proceed. |
| -metasave filename | Save Namenode's primary data structures to filename in the directory specified by hadoop.log.dir property. filename is overwritten if it exists. filename will contain one line for each of the following 1. Datanodes heart beating with Namenode 2. Blocks waiting to be replicated 3. Blocks currrently being replicated 4. Blocks waiting to be deleted |
| -setQuota quotadirname...dirname | Set the quota quota for each directory dirname. The directory quota is a long integer that puts a hard limit on the number of names in the directory tree. Best effort for the directory, with faults reported if 1. N is not a positive integer, or 2. user is not an administrator, or 3. the directory does not exist or is a file, or 4. the directory would immediately exceed the new quota. |
| -clrQuotadirname...dirname | Clear the quota for each directory dirname. Best effort for the directory. with fault reported if 1. the directory does not exist or is a file, or 2. user is not an administrator. It does not fault if the directory has no quota. |
| -restoreFailedStorage true / false / check | This option will turn on/off automatic attempt to restore failed storage replicas. If a failed storage becomes available again the system will attempt to restore edits and/or fsimage during checkpoint. 'check' option will return current setting. |
| -help [cmd] | Displays help for the given command or all commands if none is specified. |
mradmin：
运行一个mr管理客户端，用法如下：
hadoop mradmin [ GENERIC_OPTIONS ] [-refreshQueueAcls]
| -refreshQueueAcls | Refresh the queue acls used by hadoop, to check access during submissions and administration of the job by the user. The properties present in mapred-queue-acls.xml is reloaded by the queue manager. |
jobtracker：
运行一个MapReduce job tracker用法如下：
hadoop jobtracker [-dumpConfiguration]
| -dumpConfiguration | Dumps the configuration used by the JobTracker alongwith queue configuration in JSON format into Standard output used by the jobtracker and exits. |
namenode：
运行以namenode用法如下：
hadoop namenode [-format] | [-upgrade] | [-rollback] | [-finalize] | [-importCheckpoint]
| -format | Formats the namenode. It starts the namenode, formats it and then shut it down. |
| -upgrade | Namenode should be started with upgrade option after the distribution of new hadoop version. |
| -rollback | Rollsback the namenode to the previous version. This should be used after stopping the cluster and distributing the old hadoop version. |
| -finalize | Finalize will remove the previous state of the files system. Recent upgrade will become permanent. Rollback option will not be available anymore. After finalization it shuts the namenode down. |
| -importCheckpoint | Loads image from a checkpoint directory and save it into the current one. Checkpoint dir is read from property fs.checkpoint.dir |
secondarynamenode：
运行一个hdfs的secondary namenode用法如下：
hadoop secondarynamenode [-checkpoint [force]] | [-geteditsize]
| -checkpoint [-force] | Checkpoints the Secondary namenode if EditLog size >= fs.checkpoint.size. If -force is used, checkpoint irrespective of EditLog size. |
| -geteditsize | Prints the EditLog size. |
tasktracker：
运行一个mr的tasktracker节点，用法如下：
hadoop tasktracker