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Detailed introduction to the wget command in Linux

黄舟
Release: 2017-06-02 10:16:52
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This article mainly introduces the wget command of Linux in detail and teaches you how to use wget. It has certain reference value. Interested friends can refer to it

Linux wget is a tool for downloading files, which is used on the command line. It is an essential tool for Linux users, especially for network administrators, who often need to download some software or restore backups from remote servers to local servers. If we use virtual host, to handle such a transaction we can only download it from the remote server to our computer disk first, and then use the ftp toolto upload to the server. This is a waste of time and energy, and there's nothing you can do about it. When it comes to Linux VPS, it can be downloaded directly to the server without going through the upload step. The wget tool is small in size but has complete functions. It supports breakpoint download function, supports FTP and HTTP download methods, supports proxy servers and is convenient and simple to set up. Below we explain how to use wget in the form of examples.

1. Use wget to download a single file

The following example downloads a file from the network and saves it in the current directory

wget http://cn.wordpress.org/wordpress-3.1-zh_CN.zip
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In the download process Progress bar will be displayed, including (download completion percentage, downloaded bytes, current download speed, remaining download time).

2. Use wget -O to download and save it with a different file name

wget defaults to the last character that matches "/" for the command. Dynamically linked downloads often have incorrect file names.
Error: The following example will download a file and save it with the name download.php?id=1080

wget http://www.centos.bz/download?id=1
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Even though the downloaded file is in zip format, it is still ordered with download.php?id=1080.
Correct: In order to solve this problem, we can use the parameter -O to specify a file name:

wget -O wordpress.zip http://www.centos.bz/download.php?id=1080
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3. Use wget –limit -rate speed limit download

When you execute wget, it will occupy all possible bandwidth downloads by default. But when you are going to download a large file and you also need to download other files, it is necessary to limit the speed.

wget –limit-rate=300k http://cn.wordpress.org/wordpress-3.1-zh_CN.zip
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4. Use wget -c to resume the download after a breakpoint

Use wget -c to restart the download of the interrupted file:

wget -c http://cn.wordpress.org/wordpress-3.1-zh_CN.zip
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It is very helpful when we download a large file and it is suddenly interrupted due to network and other reasons. We can continue downloading instead of re-downloading a file. You can use the -c parameter when you need to continue an interrupted download.

5. Use wget -b background download

When downloading very large files, we can use the parameter -b to perform background download.

wget -b http://cn.wordpress.org/wordpress-3.1-zh_CN.zip
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Continuing in background, pid 1840.
Output will be written to `wget-log'.

you You can use the following command to check the download progress

tail -f wget-log

6. Disguise proxy name download

Some websites can reject your download request by judging that the proxy name is not a browser. But you can disguise it through the --user-agent parameter.

wget –user-agent=”Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.204 Safari/534.16″ 下载链接
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7. Use wget –spider to test the download link

When you plan to perform scheduled downloads, you should test whether the download link is valid at the scheduled time. We can add the –spider parameter to check.

wget –spider URL
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If the download link is correct,

wget –spider URL 
Spider mode enabled. Check if remote file exists. 
HTTP request sent, awaiting response… 200 OK 
Length: unspecified [text/html] 
Remote file exists and could contain further links, 
but recursion is disabled — not retrieving.
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will be displayed. This ensures that the download can be carried out at the scheduled time, but when you give a wrong link, the following error will be displayed

wget –spider url 
Spider mode enabled. Check if remote file exists. 
HTTP request sent, awaiting response… 404 Not Found 
Remote file does not exist — broken link!!!
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You can use the spider parameter in the following situations:

Check before scheduled download
Check whether the website is available at intervals
Check the dead links of the website page

8. Use wget –tries to increase the number of retries

It may also fail if there is a network problem or downloading a large file. By default, wget retries 20 times to connect and download files. If necessary, you can use --tries to increase the number of retries.

wget –tries=40 URL
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9. Use wget -i to download multiple files

First, save a download link file

cat > file list.txt
url1
url2
url3
url4
Then use this file and parameters -i to download

wget -i filelist.txt
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10. Use wget –mirror mirror website

The following example is to download the entire website to the local.

wget –mirror -p –convert-links -P ./LOCAL URL
–miror: Account opening mirror download
-p: Download all files for normal html page display
–convert -links: After downloading, convert to local links
-P ./LOCAL: Save all files and directories to the local specified directory

11. Use wget –reject to filter downloads in the specified format

你想下载一个网站,但你不希望下载图片,你可以使用以下命令。

wget –reject=gif url
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12、使用wget -o把下载信息存入日志文件

你不希望下载信息直接显示在终端而是在一个日志文件,可以使用以下命令:

wget -o download.log URL
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13、使用wget -Q限制总下载文件大小

当你想要下载的文件超过5M而退出下载,你可以使用以下命令:

wget -Q5m -i filelist.txt
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注意:这个参数对单个文件下载不起作用,只能递归下载时才有效。

14、使用wget -r -A下载指定格式文件

可以在以下情况使用该功能

下载一个网站的所有图片
下载一个网站的所有视频
下载一个网站的所有PDF文件

wget -r -A.pdf url
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15、使用wget FTP下载

你可以使用wget来完成ftp链接的下载。
使用wget匿名ftp下载

wget ftp-url
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使用wget用户名和密码认证的ftp下载

wget –ftp-user=USERNAME –ftp-password=PASSWORD url
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wget是在Linux下开发的开放源代码的软件,作者是Hrvoje Niksic,后来被移植到包括Windows在内的各个平台上。它有以下功能和特点:

(1)支持断点下传功能;这一点,也是网络蚂蚁和FlashGet当年最大的卖点,现在,Wget也可以使用此功能,那些网络不是太好的用户可以放心了;
(2)同时支持FTP和HTTP下载方式;尽管现在大部分软件可以使用HTTP方式下载,但是,有些时候,仍然需要使用FTP方式下载软件;
(3)支持代理服务器;对安全强度很高的系统而言,一般不会将自己的系统直接暴露在互联网上,所以,支持代理是下载软件必须有的功能;
(4)设置方便简单;可能,习惯图形界面的用户已经不是太习惯命令行了,但是,命令行在设置上其实有更多的优点,最少,鼠标可以少点很多次,也不要担心是否错点鼠标;
(5)程序小,完全免费;程序小可以考虑不计,因为现在的硬盘实在太大了;完全免费就不得不考虑了,即使网络上有很多所谓的免费软件,但是,这些软件的广告却不是我们喜欢的;

wget虽然功能强大,但是使用起来还是比较简单的,基本的语法是:wget [参数列表] URL。下面就结合具体的例子来说明一下wget的用法。

1、下载整个http或者ftp站点。

wget http://place.your.url/here
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这个命令可以将下载下来。使用-x会强制建立服务器上一模一样的目录,如果使用-nd参数,那么服务器上下载的所有内容都会加到本地当前目录。

wget -r http://place.your.url/here
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这 个命令会按照递归的方法,下载服务器上所有的目录和文件,实质就是下载整个网站。这个命令一定要小心使用,因为在下载的时候,被下载网站指向的所有地址同 样会被下载,因此,如果这个网站引用了其他网站,那么被引用的网站也会被下载下来!基于这个原因,这个参数不常用。可以用-l number参数来指定下载的层次。例如只下载两层,那么使用-l 2。

要是您想制作镜像站点,那么可以使用-m参数,例如:wget -m http://place.your.url/here
这时wget会自动判断合适的参数来制作镜像站点。此时,wget会登录到服务器上,读入robots.txt并按robots.txt的规定来执行。

2、断点续传。
当文件特别大或者网络特别慢的时候,往往一个文件还没有下载完,连接就已经被切断,此时就需要断点续传。wget的断点续传是自动的,只需要使用-c参数,例如:

wget -c http://the.url.of/incomplete/file
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使用断点续传要求服务器支持断点续传。-t参数表示重试次数,例如需要重试100次,那么就写-t 100,如果设成-t 0,那么表示无穷次重试,直到连接成功。-T参数表示超时等待时间,例如-T 120,表示等待120秒连接不上就算超时。

3、批量下载。

如果有多个文件需要下载,那么可以生成一个文件,把每个文件的URL写一行,例如生成文件download.txt,然后用命令:wget -i download.txt
这样就会把download.txt里面列出的每个URL都下载下来。(如果列的是文件就下载文件,如果列的是网站,那么下载首页)

4、选择性的下载。

可以指定让wget只下载一类文件,或者不下载什么文件。例如:

wget -m –reject=gif http://target.web.site/subdirectory
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但是忽略gif文件。–accept=LIST 可以接受的文件类型,–reject=LIST拒绝接受的文件类型。

5、密码和认证。

wget只能处理利用用户名/密码方式限制访问的网站,可以利用两个参数:
–http-user=USER设置HTTP用户
–http-passwd=PASS设置HTTP密码
对于需要证书做认证的网站,就只能利用其他下载工具了,例如curl。

6、利用代理服务器进行下载。

如果用户的网络需要经过代理服务器,那么可以让wget通过代理服务器进行文件的下载。此时需要在当前用户的目录下创建一个.wgetrc文件。文件中可以设置代理服务器:

http-proxy = 111.111.111.111:8080 
ftp-proxy = 111.111.111.111:8080
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分别表示http的代理服务器和ftp的代理服务器。如果代理服务器需要密码则使用:
–proxy-user=USER设置代理用户
–proxy-passwd=PASS设置代理密码
这两个参数。
使用参数–proxy=on/off 使用或者关闭代理。
wget还有很多有用的功能,需要用户去挖掘。

附录:

命令格式:
wget [参数列表] [目标软件、网页的网址]

-V,–version 显示软件版本号然后退出;
-h,–help显示软件帮助信息;
-e,–execute=COMMAND 执行一个 “.wgetrc”命令

-o,–output-file=FILE 将软件输出信息保存到文件;
-a,–append-output=FILE将软件输出信息追加到文件;
-d,–debug显示输出信息;
-q,–quiet 不显示输出信息;
-i,–input-file=FILE 从文件中取得URL;

-t,–tries=NUMBER 是否下载次数(0表示无穷次)
-O –output-document=FILE下载文件保存为别的文件名
-nc, –no-clobber 不要覆盖已经存在的文件
-N,–timestamping只下载比本地新的文件
-T,–timeout=SECONDS 设置超时时间
-Y,–proxy=on/off 关闭代理

-nd,–no-directories 不建立目录
-x,–force-directories 强制建立目录

–http-user=USER设置HTTP用户
–http-passwd=PASS设置HTTP密码
–proxy-user=USER设置代理用户
–proxy-passwd=PASS设置代理密码

-r,–recursive 下载整个网站、目录(小心使用)
-l,–level=NUMBER 下载层次

-A,–accept=LIST 可以接受的文件类型
-R,–reject=LIST拒绝接受的文件类型
-D,–domains=LIST可以接受的域名
–exclude-domains=LIST拒绝的域名
-L,–relative 下载关联链接
–follow-ftp 只下载FTP链接
-H,–span-hosts 可以下载外面的主机
-I,–include-directories=LIST允许的目录
-X,–exclude-directories=LIST 拒绝的目录

中文文档名在平常的情况下会被编码, 但是在 –cut-dirs 时又是正常的,

wget -r -np -nH –cut-dirs=3 ftp://host/test/
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测试.txt

wget -r -np -nH -nd ftp://host/test/ 
%B4%FA%B8%D5.txt 
wget “ftp://host/test/*” 
%B4%FA%B8%D5.txt
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由 於不知名的原因,可能是为了避开特殊档名, wget 会自动将抓取档名的部分用 encode_string 处理过, 所以该 patch 就把被 encode_string 处理成 “%3A” 这种东西, 用 decode_string 还原成 “:”,并套用在目录与档案名称的部分,decode_string 是 wget 内建的函式。

wget -t0 -c -nH -x -np -b -m -P /home/sunny/NOD32view/ http://downloads1.kaspersky-labs.com/bases/ -o wget.log
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