pig的基本操作（对hadoop文件）

pig是什么？

我的理解是： pig就相当于 shell ,  hadoop就相当于linux  (所以我尽可能的会使用pig操作hadoop的文件)

1.进入HADOOP_HOME目录。
2.执行sh bin/hadoop
我们可以看到更多命令的说明信息：
Usage: hadoop [--config confdir] COMMAND
where COMMAND is one of:
  namenode -format     format the DFS filesystem
  secondarynamenode    run the DFS secondary namenode
  namenode             run the DFS namenode
  datanode             run a DFS datanode
  dfsadmin             run a DFS admin client
  fsck                 run a DFS filesystem checking utility
  fs                   run a generic filesystem user client
  balancer             run a cluster balancing utility
  jobtracker           run the MapReduce job Tracker node
  pipes                run a Pipes job
  tasktracker          run a MapReduce task Tracker node
  job                  manipulate MapReduce jobs
  queue                get information regarding JobQueues
  version              print the version
  jar <jar>            run a jar file
  distcp <srcurl> <desturl> copy file or directories recursively
  archive -archiveName NAME <src>* <dest> create a hadoop archive
  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.

常用pig命令

例如： 查看文件大小

grunt> fs -du -h -s 文件名
19.4 G  文件名

grunt> help
Commands:
<pig latin statement>; - See the PigLatin manual for details: http://hadoop.apache.org/pig
File system commands:
    fs <fs arguments> - Equivalent to Hadoop dfs command: http://hadoop.apache.org/common/docs/current/hdfs_shell.html
Diagnostic commands:
    describe <alias>[::<alias] - Show the schema for the alias. Inner aliases can be described as A::B.
    explain [-script <pigscript>] [-out <path>] [-brief] [-dot|-xml] [-param <param_name>=<param_value>]
        [-param_file <file_name>] [<alias>] - Show the execution plan to compute the alias or for entire script.
        -script - Explain the entire script.
        -out - Store the output into directory rather than print to stdout.
        -brief - Don't expand nested plans (presenting a smaller graph for overview).
        -dot - Generate the output in .dot format. Default is text format.
        -xml - Generate the output in .xml format. Default is text format.
        -param <param_name - See parameter substitution for details.
        -param_file <file_name> - See parameter substitution for details.
        alias - Alias to explain.
    dump <alias> - Compute the alias and writes the results to stdout.
Utility Commands:
    exec [-param <param_name>=param_value] [-param_file <file_name>] <script> - 
        Execute the script with access to grunt environment including aliases.
        -param <param_name - See parameter substitution for details.
        -param_file <file_name> - See parameter substitution for details.
        script - Script to be executed.
    run [-param <param_name>=param_value] [-param_file <file_name>] <script> - 
        Execute the script with access to grunt environment. 
        -param <param_name - See parameter substitution for details.
        -param_file <file_name> - See parameter substitution for details.
        script - Script to be executed.
    sh  <shell command> - Invoke a shell command.
    kill <job_id> - Kill the hadoop job specified by the hadoop job id.
    set <key> <value> - Provide execution parameters to Pig. Keys and values are case sensitive.
        The following keys are supported: 
        default_parallel - Script-level reduce parallelism. Basic input size heuristics used by default.
        debug - Set debug on or off. Default is off.
        job.name - Single-quoted name for jobs. Default is PigLatin:<script name>
        job.priority - Priority for jobs. Values: very_low, low, normal, high, very_high. Default is normal
        stream.skippath - String that contains the path. This is used by streaming.
        any hadoop property.
    help - Display this message.
    history [-n] - Display the list statements in cache.
        -n Hide line numbers. 
    quit - Quit the grunt shell.