http://zhangrenfang8738.blog.163.com/blog/static/95401881201142711450245/
监控站点首页下载时间：
curl -o /dev/null -s -w ‘%{time_total}’ http://www.miotour.com
curl -o /dev/null -s -w ‘%{http_code}’ http://www.miotour.com
curl -o /dev/null -s -w %{http_code}:%{time_connect}:%{time_starttransfer}:%{time_total} http://www.miotour.com
结果：2.547
-s 静默输出；没有-s的话就是下面的情况，这是在脚本等情况下不需要的信息。
监控首页各项时间指标：
curl -o /dev/null -s -w ‘%{time_connect}:%{time_starttransfer}:%{time_total}’ http://www.miotour.com
结果： 0.244: 1.044: 2.672
时间指标解释 ：
time_connect 建立到服务器的 TCP 连接所用的时间
time_starttransfer 在发出请求之后，Web 服务器返回数据的第一个字节所用的时间
time_total 完成请求所用的时间
在 发出请求之后，Web 服务器处理请求并开始发回数据所用的时间是
（time_starttransfer）1.044 - （time_connect）0.244 = 0.8 秒
客户机从服务器下载数据所用的时间是
（time_total）2.672 - （time_starttransfer）1.044 = 1.682 秒
使用 cURL 获取站点的各类响应时间 – dns解析时间,响应时间,传输时间等：
Example
1
curl -o /dev/null -s -w %{http_code}:%{http_connect}:%{content_type}:%{time_namelookup}:%{time_redirect}:%{time_pretransfer}:%{time_connect}:%{time_starttransfer}:%{time_total}:%{speed_download} digdeeply.org
这是一个本人博客站点执行 curl 命令的情况。输出通常是 HTML 代码，通过 -o 参数发送到 /dev/null。-s 参数去掉所有状态信息。-w 参数让 curl 输出的计时器的状态信息。
一次http请求中的各个时间段-dns解析,等待服务器响应,获取内容等
一次http请求中的各个时间段-dns解析,等待服务器响应,获取内容等
下边对-w参数做个详细的解释，由我(DigDeeply)翻译。有不对的地方请大家指出。(英文原文：http://curl.haxx.se/docs/manpage.html)
以下是可用的变量名：
-w, --write-out
以下变量会按CURL认为合适的格式输出，输出变量需要按照%{variable_name}的格式，如果需要输出%，double一下即可，即%%，同时，n是换行，r是回车，t是TAB。
url_effective The URL that was fetched last. This is most meaningful if you've told curl to follow location: headers.
filename_effective The ultimate filename that curl writes out to. This is only meaningful if curl is told to write to a file with the --remote-name or --output option. It's most useful in combination with the --remote-header-name option. (Added in 7.25.1)
http_code http状态码，如200成功,301转向,404未找到,500服务器错误等。(The numerical response code that was found in the last retrieved HTTP(S) or FTP(s) transfer. In 7.18.2 the alias response_code was added to show the same info.)
http_connect The numerical code that was found in the last response (from a proxy) to a curl CONNECT request. (Added in 7.12.4)
time_total 总时间，按秒计。精确到小数点后三位。 （The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.）
time_namelookup DNS解析时间,从请求开始到DNS解析完毕所用时间。(The time, in seconds, it took from the start until the name resolving was completed.)
time_connect 连接时间,从开始到建立TCP连接完成所用时间,包括前边DNS解析时间，如果需要单纯的得到连接时间，用这个time_connect时间减去前边time_namelookup时间。以下同理，不再赘述。(The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.)
time_appconnect 连接建立完成时间，如SSL/SSH等建立连接或者完成三次握手时间。(The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed. (Added in 7.19.0))
time_pretransfer 从开始到准备传输的时间。(The time, in seconds, it took from the start until the file transfer was just about to begin. This includes all pre-transfer commands and negotiations that are specific to the particular protocol(s) involved.)
time_redirect 重定向时间，包括到最后一次传输前的几次重定向的DNS解析，连接，预传输，传输时间。(The time, in seconds, it took for all redirection steps include name lookup, connect, pretransfer and transfer before the final transaction was started. time_redirect shows the complete execution time for multiple redirections. (Added in 7.12.3))
time_starttransfer 开始传输时间。在发出请求之后，Web 服务器返回数据的第一个字节所用的时间(The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pretransfer and also the time the server needed to calculate the result.)
size_download 下载大小。(The total amount of bytes that were downloaded.)
size_upload 上传大小。(The total amount of bytes that were uploaded.)
size_header 下载的header的大小(The total amount of bytes of the downloaded headers.)
size_request 请求的大小。(The total amount of bytes that were sent in the HTTP request.)
speed_download 下载速度，单位-字节每秒。(The average download speed that curl measured for the complete download. Bytes per second.)
speed_upload 上传速度,单位-字节每秒。(The average upload speed that curl measured for the complete upload. Bytes per second.)
content_type 就是content-Type，不用多说了，这是一个访问我博客首页返回的结果示例(text/html; charset=UTF-8)；(The Content-Type of the requested document, if there was any.)
num_connects Number of new connects made in the recent transfer. (Added in 7.12.3)
num_redirects Number of redirects that were followed in the request. (Added in 7.12.3)
redirect_url When a HTTP request was made without -L to follow redirects, this variable will show the actual URL a redirect would take you to. (Added in 7.18.2)
ftp_entry_path The initial path libcurl ended up in when logging on to the remote FTP server. (Added in 7.15.4)
ssl_verify_result ssl认证结果，返回0表示认证成功。( The result of the SSL peer certificate verification that was requested. 0 means the verification was successful. (Added in 7.19.0))
若多次使用-w参数，按最后一个的格式输出。If this option is used several times, the last one will be used.
转载请注明：来自：DigDeeply’s Blog–使用 cURL 获取站点的各类响应时间 – dns解析时间,响应时间,传输时间