Nutch 1.3 学习笔记2

1. Nutch 1.3 运行命令的一些介绍

   要看Nutch的命令说明，可执行如下命令bin/nutch
  

  Usage: nutch [-core] COMMAND
     where COMMAND is one of:
     crawl             one-step crawler for intranets
     readdb            read / dump crawl db
     convdb            convert crawl db from pre-0.9 format
     mergedb           merge crawldb-s, with optional filtering
     readlinkdb        read / dump link db
     inject            inject new urls into the database
     generate          generate new segments to fetch from crawl db
     freegen           generate new segments to fetch from text files
     fetch             fetch a segment's pages
     parse             parse a segment's pages
     readseg           read / dump segment data
     mergesegs         merge several segments, with optional filtering and slicing
     updatedb          update crawl db from segments after fetching
     invertlinks       create a linkdb from parsed segments
     mergelinkdb       merge linkdb-s, with optional filtering
     solrindex         run the solr indexer on parsed segments and linkdb
     solrdedup         remove duplicates from solr
     solrclean         remove HTTP 301 and 404 documents from solr
     plugin            load a plugin and run one of its classes main()
    or
     CLASSNAME         run the class named CLASSNAME
 Most commands print help when invoked w/o parameters.


 Expert: -core option is for developers only. It avoids building the job jar,
         instead it simply includes classes compiled with ant compile-core.
         NOTE: this works only for jobs executed in 'local' mode

2. 单个命令的说明

2.1 bin/nutch crawl

Usage: Crawl <urlDir> -solr <solrURL> [-dir d] [-threads n] [-depth i] [-topN N]
这是用于对urls进行一键式抓取的命令

2.2 bin/nutch readdb 

Usage: CrawlDbReader <crawldb> (-stats | -dump <out_dir> | -topN <nnnn> <out_dir> [<min>] | -url <url>)
这是用于对crawldb数据库进行读取的命令，主要是用于dump相应的url文件

2.3 bin/nutch convdb 

这个命令主要用于把nutch 0.9的crawldb数据转换成1.3的格式

2.4 bin/nutch mergedb

Usage: CrawlDbMerger <output_crawldb> <crawldb1> [<crawldb2> <crawldb3> ...] [-normalize] [-filter]
这个命令主要用于合并多个crawldb数据库

2.5 bin/nutch readlinkdb

Usage: LinkDbReader <linkdb> {-dump <out_dir> | -url <url>)
主要用于读取invertlinks产生的链接数据

2.6 bin/nutch inject

Usage: Injector <crawldb> <url_dir>
主要用于把url_dir中的url注入到crawldb数据库中去

2.7 bin/nutch generate

Usage: Generator <crawldb> <segments_dir> [-force] [-topN N] [-numFetchers numFetchers] [-adddays numDays] [-noFilter] [-noNorm][-maxNumSegments num]
用于产生准备抓取的url列表

2.8 bin/nutch freegen

Usage: FreeGenerator <inputDir> <segmentsDir> [-filter] [-normalize]
从文本文件中提取urls来产生新的抓取segment

2.9 bin/nutch fetch

Usage: Fetcher <segment> [-threads n] [-noParsing]
主要用来对generate产生的urls进行抓取，这里用到了Hadoop架构，使用了一个FetcherOutputFormat来对其结果进行多目录输出

2.10 bin/nutch parse

Usage: ParseSegment segment
主要是对抓取的内容进行分析

2.11 bin/nutch readseg

Usage: SegmentReader (-dump ... | -list ... | -get ...) [general options]
这个命令主要是输出segment的内容

2.12 bin/nutch invertlinks

Usage: LinkDb <linkdb> (-dir <segmentsDir> | <seg1> <seg2> ...) [-force] [-noNormalize] [-noFilter]
这个命令主要是得到抓取内容的外链接数据

2.13 bin/nutch solrindex

Usage: SolrIndexer <solr url> <crawldb> <linkdb> (<segment> ... | -dir <segments>)
对抓以的内容进行索引建立，前提是要有solr环境。

2.14 bin/nutch plugin

Usage: PluginRepository pluginId className [arg1 arg2 ...]
这个命令主要对插件进行测试，运行其main方法