CURL 於 CLI 顯示 TCP、SSL 的連線時間

Linux 於 CLI 使用 CURL 想要測試看看網站的詳細連線速度，要怎麼做呢？

註：此篇「httpstat 分析 從 DNS查詢 到 下載完成各個階段的處理時間」也是使用 CURL 類似做法達成的，此篇是更簡化的版本。

CURL 於 CLI 顯示 TCP、SSL 的連線時間

CURL 要顯示詳細連線時間，可以使用下述命令：

• $ curl -o /dev/null -s -w "%{time_connect} + %{time_starttransfer} = %{time_total}\n" https://blog.longwin.com.tw

此篇文章作者將上述做點美化，下述摘錄自此篇：Timing Details With cURL – Joseph Scott

1. vim ~/curl-format.txt

   \n
      time_namelookup:  %{time_namelookup}\n
         time_connect:  %{time_connect} (TCP handshake)\n
      time_appconnect:  %{time_appconnect} (SSL handshake)\n
     time_pretransfer:  %{time_pretransfer}\n
       ¦time_redirect:  %{time_redirect}\n
   time_starttransfer:  %{time_starttransfer}\n
                      ----------\n
           time_total:  %{time_total}\n
   \n

2. $ curl -w "@curl-format.txt" -so /dev/null https://blog.longwin.com.tw
   • -w "@curl-format.txt" tells cURL to use our format file
   • -o /dev/null redirects the output of the request to /dev/null
   • -s tells cURL not to show a progress meter

上述的語法還是比較難記憶，寫成 Bash shell function 比較好用：

1. vim ~/.bashrc

   function curltime {
       # curl -o /dev/null -s -w "%{time_connect} + %{time_starttransfer} = %{time_total}\n" "$1"
       curl -w "@curl-format.txt" -so /dev/null "$1"
   }

2. source ~/.bashrc
3. curltime https://blog.longwin.com.tw

CURL 相關參數

CURL 除了上述的參數外，還有哪些參數可以使用呢？

• man curl # 搜尋 -w, --write-out <format>
• The variables available are:
  • content_type：The Content-Type of the requested document, if there was any.
  • 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.
  • ftp_entry_path：The initial path curl ended up in when logging on to the remote FTP server.
  • http_code：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.
  • local_ip：The IP address of the local end of the most recently done connection - can be either IPv4 or IPv6
  • local_port：The local port number of the most recently done connection
  • num_connects：Number of new connects made in the recent transfer.
  • num_redirects：Number of redirects that were followed in the request.
  • redirect_url：When an HTTP request was made without -L to follow redirects, this variable will show the actual URL a redirect would take you to.
  • remote_ip：The remote IP address of the most recently done connection - can be either IPv4 or IPv6
  • remote_port：The remote port number of the most recently done connection
  • size_download：The total amount of bytes that were downloaded.
  • size_header：The total amount of bytes of the downloaded headers.
  • size_request：The total amount of bytes that were sent in the HTTP request.
  • size_upload：The total amount of bytes that were uploaded.
  • speed_download：The average download speed that curl measured for the complete download. Bytes per second.
  • speed_upload：The average upload speed that curl measured for the complete upload. Bytes per second.
  • ssl_verify_result：The result of the SSL peer certificate verification that was requested. 0 means the verification was successful.
  • time_appconnect：The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed.
  • time_connect：The time, in seconds, it took from the start until the TCP connect to the remote host (or proxy) was completed.
  • time_namelookup：The time, in seconds, it took from the start until the name resolving was completed.
  • time_pretransfer：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：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.
  • time_starttransfer：The time, in seconds, it took from the start until the first byte was just about to be transferred. This includes time_pre‐transfer and also the time the server needed to calculate the result.
  • time_total：The total time, in seconds, that the full operation lasted. The time will be displayed with millisecond resolution.
  • url_effective：The URL that was fetched last. This is most meaningful if you've told curl to follow location: headers.

相關網頁

• How do I measure request and response times at once using cURL?
• Timing HTTP Requests with cURL - overloaded.io
• Find the Time to First Byte Using Curl

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