linux使用wget

wget is a Linux command-line utility for retrieving files from the web, via HTTP, HTTPS and FTP protocols. When you are using wget to download a file at a particular HTTP url, wget sends an appropriate HTTP request to a destination web server.

To view default HTTP request header being sent by wget, you can use "-d" option.

$ wget -d http://www.google.com/

---request begin---
GET / HTTP/1.0
User-Agent: Wget/1.12 (linux-gnu)
Accept: */*
Host: www.google.com
Connection: Keep-Alive

---request end---

Sometimes you may want to customize the default HTTP request header used by wget. For example, you may want to customize "User-Agent" field as some sites rely on "User-Agent" string to block robots like wget to retrieve their content. You may want to add an additional "Accept-Encoding" field in order to test encoding schemes of your web server. In some other cases, you may need to set "Host" field properly to be able to access a web server running on name-based virtual hosting.

wget allows you to send an HTTP request with custom HTTP headers. To supply custom HTTP headers, use "--header" option. You can use "--header" option as many time as you want in a single run.

$ wget -d --header="User-Agent: Mozilla/5.0 (Windows NT 6.0) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11" --header="Referer: http://xmodulo.com/" --header="Accept-Encoding: compress, gzip" http://www.google.com/

---request begin---
GET / HTTP/1.0
User-Agent: Mozilla/5.0 (Windows NT 6.0) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11
Accept: */*
Host: www.google.com
Connection: Keep-Alive
Referer: http://xmodulo.com/
Accept-Encoding: compress, gzip

---request end---

If you would like to permanently set the default HTTP request header you want to use with wget, you can use ~/.wgetrc configuration file. You can specify as many header fields as you want in ~/.wgetrc.

$ vi ~/.wgetrc

header = User-Agent: Mozilla/5.0 (Windows NT 6.0) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.97 Safari/537.11
header = Referer: http://xmodulo.com/
header = Accept-Encoding: compress, gzip

Once you have configured ~/.wgetrc, you no longer need to use "--header" option with wget.

curl is another command-line tool with similar functionality as wget. The curl utility also allows you to set a custom HTTP header. Refer to this guideline for detail on curl.