eg:http://hgdownload.soe.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeAwgDnaseUniform/
下载该路径下的所有文件
wget http://hgdownload.soe.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeAwgDnaseUniform/
得到一个 index.html 文件
然后
wget -i index.html -F -B http://hgdownload.soe.ucsc.edu/goldenPath/hg19/encodeDCC/wgEncodeAwgDnaseUniform/
-i file
--input-file=file
Read URLs from a local or external file. If - is specified as file, URLs are read from the standard input. (Use ./- to read from a file literally named -.)
从文件 index.html 中导入链接，默认按行读取URL
-F
--force-html
When input is read from a file, force it to be treated as an HTML file. This enables you to retrieve relative links from existing HTML files on your local disk, by adding "" to HTML, or using the --base command-line option.
将文件以HTML格式解析，（其实就是解析<a>?）<a> 代表链接
-B URL
--base=URL
Resolves relative links using URL as the point of reference, when reading links from an HTML file specified via the -i/--input-file option (together with --force-html, or when the input file was fetched remotely from a server describing it as HTML). This is equivalent to the presence of a "BASE" tag in the HTML input file, with URL as the value for the "href" attribute.
因为发现解析出来的链接用的都是相对路径，而为了下载这个文件，必须在相对路径前添加上Base URL，-B就是用来添加Base URL。
来自：http://blog.51cto.com/geekbin/1405252
