使用wget工具抓取网页和图片 成功尝试

使用wget工具抓取网页和图片

发表于1年前(2014-12-17 11:29)   阅读( 2471) | 评论(14) 85人收藏此文章, 我要收藏
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wget  网页抓取  图片抓取

 

目录[-]

  • 奇怪的需求
  • wget概述
  • wget尝试
  • wget正解

奇怪的需求

公司需要将服务器的网页缓存到路由器,用户在访问该网页时就直接取路由器上的缓存即可。虽然我不知道这个需求有什么意义,但还是尽力去实现吧。

wget概述

wget是unix和类unix下的一个网页抓取工具,待我熟悉它后,发现它的功能远不止这些。但是这篇博文只说怎么抓取一个指定URL以及它下面的相关内容(包括html,js,css,图片)并将内容里的绝对路径换成相对路径。网上搜到一堆有关wget的文章,关于它怎么抓取网页和相关的图片资源,反正我是没有找到一篇实用的,都以失败告终。

这是wget -h > ./help_wget.txt 后的文件内容

 

 

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GNU Wget 1.16, a non-interactive network retriever.
 
Usage: wget [OPTION]... [URL]...
 
Mandatory arguments to long options are mandatory for short options too.
 
 
 
Startup:
 
   -V,  --version                   display the version of Wget and exit .
 
   -h,  --help                      print this help.
 
   -b,  --background                go to background after startup.
 
   -e,  --execute=COMMAND           execute a `.wgetrc'-style command .
 
 
 
Logging and input file :
 
   -o,  --output- file =FILE          log messages to FILE.
 
   -a,  --append-output=FILE        append messages to FILE.
 
   -q,  --quiet                     quiet (no output).
 
   - v ,  --verbose                   be verbose (this is the default).
 
   -nv, --no-verbose                turn off verboseness, without being quiet.
 
        --report-speed=TYPE         Output bandwidth as TYPE.  TYPE can be bits.
 
   -i,  --input- file =FILE           download URLs found in local or external FILE.
 
   -F,  --force-html                treat input file as HTML.
 
   -B,  --base=URL                  resolves HTML input- file links (-i -F)
 
                                    relative to URL.
 
        --config=FILE               Specify config file to use.
 
        --no-config                 Do not read any config file .
 
Download:
 
   -t,  --tries=NUMBER              set number of retries to NUMBER (0 unlimits).
 
        --retry-connrefused         retry even if connection is refused.
 
   -O,  --output-document=FILE      write documents to FILE.
 
   - nc , --no-clobber                skip downloads that would download to
 
                                    existing files (overwriting them).
 
   -c,  -- continue                  resume getting a partially-downloaded file .
 
        --start-pos=OFFSET          start downloading from zero-based position OFFSET.
 
        --progress=TYPE             select progress gauge type .
 
        --show-progress             display the progress bar in any verbosity mode.
 
   -N,  --timestamping              don't re-retrieve files unless newer than
 
                                    local .
 
   --no-use-server-timestamps       don 't set the local file' s timestamp by
 
                                    the one on the server.
 
   -S,  --server-response           print server response.
 
        --spider                    don't download anything.
 
   -T,  --timeout=SECONDS           set all timeout values to SECONDS.
 
        --dns-timeout=SECS          set the DNS lookup timeout to SECS.
 
        --connect-timeout=SECS      set the connect timeout to SECS.
 
        -- read -timeout=SECS         set the read timeout to SECS.
 
   -w,  --wait=SECONDS              wait SECONDS between retrievals.
 
        --waitretry=SECONDS         wait 1..SECONDS between retries of a retrieval.
 
        --random-wait               wait from 0.5*WAIT...1.5*WAIT secs between retrievals.
 
        --no-proxy                  explicitly turn off proxy.
 
   -Q,  -- quota =NUMBER              set retrieval quota to NUMBER.
 
        --bind-address=ADDRESS      bind to ADDRESS ( hostname or IP) on local host.
 
        --limit-rate=RATE           limit download rate to RATE.
 
        --no-dns-cache              disable caching DNS lookups.
 
        --restrict- file -names=OS    restrict chars in file names to ones OS allows.
 
        --ignore- case               ignore case when matching files /directories .
 
   -4,  --inet4-only                connect only to IPv4 addresses.
 
   -6,  --inet6-only                connect only to IPv6 addresses.
 
        --prefer-family=FAMILY      connect first to addresses of specified family,
 
                                    one of IPv6, IPv4, or none.
 
        --user=USER                 set both ftp and http user to USER.
 
        --password=PASS             set both ftp and http password to PASS.
 
        --ask-password              prompt for passwords.
 
        --no-iri                    turn off IRI support.
 
        -- local -encoding=ENC        use ENC as the local encoding for IRIs.
 
        --remote-encoding=ENC       use ENC as the default remote encoding.
 
        --unlink                    remove file before clobber.
 
 
 
Directories:
 
   -nd, --no-directories            don't create directories.
 
   -x,  --force-directories         force creation of directories.
 
   -nH, --no-host-directories       don't create host directories.
 
        --protocol-directories      use protocol name in directories.
 
   -P,  --directory-prefix=PREFIX   save files to PREFIX/...
 
        -- cut - dirs =NUMBER           ignore NUMBER remote directory components.
 
 
 
HTTP options:
 
        --http-user=USER            set http user to USER.
 
        --http-password=PASS        set http password to PASS.
 
        --no-cache                  disallow server-cached data.
 
        --default-page=NAME         Change the default page name (normally
 
                                    this is `index.html'.).
 
   -E,  --adjust-extension          save HTML /CSS documents with proper extensions.
 
        --ignore-length             ignore `Content-Length' header field.
 
        --header=STRING             insert STRING among the headers.
 
        --max-redirect              maximum redirections allowed per page.
 
        --proxy-user=USER           set USER as proxy username.
 
        --proxy-password=PASS       set PASS as proxy password.
 
        --referer=URL               include `Referer: URL' header in HTTP request.
 
        --save-headers              save the HTTP headers to file .
 
   -U,  --user-agent=AGENT          identify as AGENT instead of Wget /VERSION .
 
        --no-http-keep-alive        disable HTTP keep-alive (persistent connections).
 
        --no-cookies                don't use cookies.
 
        --load-cookies=FILE         load cookies from FILE before session.
 
        --save-cookies=FILE         save cookies to FILE after session.
 
        --keep-session-cookies      load and save session (non-permanent) cookies.
 
        --post-data=STRING          use the POST method; send STRING as the data.
 
        --post- file =FILE            use the POST method; send contents of FILE.
 
        --method=HTTPMethod         use method "HTTPMethod" in the request.
 
        --body-data=STRING          Send STRING as data. --method MUST be set .
 
        --body- file =FILE            Send contents of FILE. --method MUST be set .
 
        --content-disposition       honor the Content-Disposition header when
 
                                    choosing local file names (EXPERIMENTAL).
 
        --content-on-error          output the received content on server errors.
 
        --auth-no-challenge         send Basic HTTP authentication information
 
                                    without first waiting for the server's
 
                                    challenge.
 
 
 
HTTPS (SSL /TLS ) options:
 
        --secure-protocol=PR        choose secure protocol, one of auto, SSLv2,
 
                                    SSLv3, TLSv1 and PFS.
 
        --https-only                only follow secure HTTPS links
 
        --no-check-certificate      don 't validate the server' s certificate.
 
        --certificate=FILE          client certificate file .
 
        --certificate- type =TYPE     client certificate type , PEM or DER.
 
        --private-key=FILE          private key file .
 
        --private-key- type =TYPE     private key type , PEM or DER.
 
        --ca-certificate=FILE       file with the bundle of CA's.
 
        --ca-directory=DIR          directory where hash list of CA's is stored.
 
        --random- file =FILE          file with random data for seeding the SSL PRNG.
 
        --egd- file =FILE             file naming the EGD socket with random data.
 
 
 
FTP options:
 
        -- ftp -user=USER             set ftp user to USER.
 
        -- ftp -password=PASS         set ftp password to PASS.
 
        --no-remove-listing         don 't remove `.listing' files.
 
        --no-glob                   turn off FTP file name globbing.
 
        --no-passive- ftp            disable the "passive" transfer mode.
 
        --preserve-permissions      preserve remote file permissions.
 
        --retr-symlinks             when recursing, get linked-to files (not dir ).
 
 
 
WARC options:
 
        --warc- file =FILENAME        save request /response data to a .warc.gz file .
 
        --warc-header=STRING        insert STRING into the warcinfo record.
 
        --warc-max-size=NUMBER      set maximum size of WARC files to NUMBER.
 
        --warc-cdx                  write CDX index files.
 
        --warc-dedup=FILENAME       do not store records listed in this CDX file .
 
        --no-warc-compression       do not compress WARC files with GZIP.
 
        --no-warc-digests           do not calculate SHA1 digests.
 
        --no-warc-keep-log          do not store the log file in a WARC record.
 
        --warc-tempdir=DIRECTORY    location for temporary files created by the
 
                                    WARC writer.
 
 
 
Recursive download:
 
   -r,  --recursive                 specify recursive download.
 
   -l,  --level=NUMBER              maximum recursion depth (inf or 0 for infinite).
 
        --delete-after              delete files locally after downloading them.
 
   -k,  --convert-links             make links in downloaded HTML or CSS point to
 
                                    local files.
 
        --backups=N                 before writing file X, rotate up to N backup files.
 
   -K,  --backup-converted          before converting file X, back up as X.orig.
 
   -m,  --mirror                    shortcut for -N -r -l inf --no-remove-listing.
 
   -p,  --page-requisites           get all images, etc. needed to display HTML page.
 
        --strict-comments           turn on strict (SGML) handling of HTML comments.
 
 
 
Recursive accept /reject :
 
   -A,  --accept=LIST               comma-separated list of accepted extensions.
 
   -R,  --reject=LIST               comma-separated list of rejected extensions.
 
        --accept-regex=REGEX        regex matching accepted URLs.
 
        --reject-regex=REGEX        regex matching rejected URLs.
 
        --regex- type =TYPE           regex type (posix).
 
   -D,  --domains=LIST              comma-separated list of accepted domains.
 
        --exclude-domains=LIST      comma-separated list of rejected domains.
 
        --follow- ftp                follow FTP links from HTML documents.
 
        --follow-tags=LIST          comma-separated list of followed HTML tags.
 
        --ignore-tags=LIST          comma-separated list of ignored HTML tags.
 
   -H,  --span-hosts                go to foreign hosts when recursive.
 
   -L,  --relative                  follow relative links only.
 
   -I,  --include-directories=LIST  list of allowed directories.
 
        --trust-server-names  use the name specified by the redirection
 
                                    url last component.
 
   -X,  --exclude-directories=LIST  list of excluded directories.
 
   -np, --no-parent   don't ascend to the parent directory.
 
 
Mail bug reports and suggestions to .

 

wget尝试

根据wget的帮助文档,我尝试了下面这条命令

 

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wget -r -np -pk -nH -P . /download http: //www .baidu.com

 

 

解释一下这些参数

 

-r  递归下载所有内容

-np 只下载给定URL下的内容,不下载它的上级内容

-p 下载有关页面需要用到的所有资源,包括图片和css样式

-k 将绝对路径转换为相对路径(这个很重要,为了在用户打开网页的时候,加载的相关资源都在本地寻找)

-nH 禁止wget以接收的URL为名称创建文件夹(如果没有这个,这条命令会将下载的内容存在./download/www.baidu.com/下)

-P 下载到哪个路径,这里是当前文件夹下的download文件夹下,没有的话,wget会帮你自动创建

这些选项都符合目前的这个需求,单结果很意外,并不是我们想象的那么简单,wget并没有给我们想要的东西

你如果执行了这条命令,会发现在当前的download文件夹中只是下载了一个index.html和一个robots.txt,而index.html文件所需要的图片也并没有被下载

标签中的路径也没有被替换成相对路径,可能只是去掉了"http:"这个字符串而已。

至于为什么会这样,请继续往下看。

 

wget正解

因为上面的命令行不通,所以,脑洞全开。来吧,让我们写一个shell脚本,名称为wget_cc内容如下

 

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#!/bin/sh
 
URL= "$2"
PATH= "$1"
 
echo "download url: $URL"
echo "download dir: $PATH"
 
/usr/bin/wget -e robots=off -w 1 -xq -np -nH -pk -m  -t 1 -P "$PATH" "$URL"
 
echo "success to download"

 

 

需要注意的是,我的wget是在/usr/bin目录下(这里必须写全路径),你可以使用which wget这个命令确定你的wget路径所在,然后替换到脚本中就行了。

 

这里多加了几个参数,解释一下:

-e 用法是‘-e command’

    用来执行额外的.wgetrc命令。就像vim的配置存在.vimrc文件中一样,wget也用.wgetrc文件来存放它的配置。也就是说在wget执行之前,会先执行.wgetrc文件中的配置命令。一个典型的.wgetrc文件可以参考:

    http://www.gnu.org/software/wget/manual/html_node/Sample-Wgetrc.html 

    http://www.gnu.org/software/wget/manual/html_node/Wgetrc-Commands.html

    用户可以在不改写.wgetrc文件的情况下,用-e选项指定额外的配置命令。如果想要制定多个配置命令,-e command1 -e command2 ... -e commandN即可。这些制定的配置命令,会在.wgetrc中所有命令之后执行,因此会覆盖.wgetrc中相同的配置项。

    这里robots=off是因为wget默认会根据网站的robots.txt进行操作,如果robots.txt里是User-agent: * Disallow: /的话,wget是做不了镜像或者下载目录的。

    这就是前面为什么下载不了图片和其他资源的原因所在了,因为你要爬的HOST禁止蜘蛛去爬它,而wget使用 -e robots=off 这个选项可以通过这个命令绕过这个限制。

-x 创建镜像网站对应的目录结构

-q 静默下载,即不显示下载信息,你如果想知道wget当前在下载什么资源的话,可以去掉这个选项

-m 它会打开镜像相关的选项,比如无限深度的子目录递归下载。

-t times 某个资源下载失败后的重试下载次数

-w seconds 资源请求下载之间的等待时间(减轻服务器的压力)

剩下有不懂的你就去挖文档吧。

 

写好后保存退出,执行:

 

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chmod 744 wget_cc

 

 

OK,这样脚本就能直接执行,而不用在每条命令前带 /bin/sh 让sh去解释它了。

 

下面就让脚本执行起来吧!

 

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. /wget_cc . /download http: //www .baidu.com

 

 

下载完成后的目录结构

 

使用wget工具抓取网页和图片 成功尝试_第1张图片

 

OK,然后再查看标签中的src属性,

src="img/bd_logo1.png"

果然换成了相对路径啊,大功告成,觉得对您有帮助的请点个赞吧!

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