電腦-使用curl檢測url狀況及時間
為了檢測url回應速度，可以使用curl指令，提供連線時各階段的時間，方便分析。
測試主要使用在Centos、Ubuntu。
主要會用到的參數
-w, --write-out <format> 本次主要以時間和url為主，各項時間說明可參考後續。
-o /dev/null：把回應內容丟棄 。(windows 請使用null)
-s,--silent
-S,--show-error
-L,果服務器報告所請求的頁面已移動到其他位置，則此選項將使curl重做新位置的請求，將有2段時間。
指令
curl -sSo /dev/null -w " Time_namelookup:%{time_namelookup}\n TCP_Connect time:%{time_connect}\n SSL_connect time:%{time_appconnect}\n Redirect time:%{time_redirect}\n Pretransfer:%{time_pretransfer}\n Starttransfer:%{time_starttransfer}\n Time_total:%{time_total}\n speed_download:%{speed_download}\n" https://www.google.com
輸出結果
Time_namelookup:0.004
TCP_Connect time:0.015
SSL_connect time:0.141
Redirect time:0.000
Pretransfer:0.141
Starttransfer:0.183
time_total:0.186
speed_download:63933.000
時間單位皆為秒。
Time_namelookup %{time_namelookup}
DNS 解析域名[www.google.com]的時間
TCP_Connect time：%{time_connect}
client和server端建立TCP 連接的時間
SSL_connect time：%{time_appconnect}
SSL/SSH 等上層協議建立連接的時間，比如 connect/handshake 的時間
Redirect time：%{time_redirect}
所有重定向步驟（包括名稱查找，連接，預傳輸和傳輸）所花費的時間
Pretransfer：%{time_pretransfer}
從請求開始到響應開始傳輸的時
Starttransfer：%{time_starttransfer}
從client發出請求到web的server 響應第一個字節的時間
Time_total：%{time_total}
client發出請求；到web的server發送會所有的相應數據的時間
speed_download：%{speed_download}
下載速度 單位 byte/s
根據以上時間，可以計算出以下時間
1.TCP連接時間(TCP Connection)：%{time_pretransfer}-%{time_namelookup}
2.Server 處理時間(Content Generation、Processing Time)：%{time_starttransfer}-%{time_pretransfer}
3.內容傳輸時間(Content Transfer)：%{time_total}-%{time_starttransfer}
如果指令太長，可以把先將curl輸出內容存成檔案(curl-format.txt)
\n
Time_namelookup: %{time_namelookup}\n
Time_connect: %{time_connect}\n
Time_appconnect: %{time_appconnect}\n
Time_redirect: %{time_redirect}\n
Time_pretransfer: %{time_pretransfer}\n
Time_starttransfer: %{time_starttransfer}\n
Time_total: %{time_total}\n
\n
指令
curl -w @./curl-format.txt -sSo /dev/null https://www.google.com.tw
輸出結果
Time_namelookup: 0.004
Time_connect: 0.013
Time_appconnect: 0.127
Time_redirect: 0.000
Time_pretransfer: 0.127
Time_starttransfer: 0.179
----------
Time_total: 0.182
curl 各項時間參數
time_appconnect
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_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 including 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
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.
time_total
The total time, in seconds, that the full operation lasted.
url_effective
The URL that was fetched last. This is most meaningful if you've told curl to follow location: headers.
參考資料：
curl.1 the man page
使用 curl 命令分析请求的耗时情况
CURL 於 CLI 顯示 TCP、SSL 的連線時間
Performance Testing with cURL, Part 1: Basics
Curl 查看網頁載入前的各項時間 (windows)
