Wednesday, 19 April 2017

How to show response time with cURL

cURL with Timers - Response Time

cURL supports formatted output for the details of the request ( see the cURL manpage for details, under “-w, –write-out ” ). For our purposes we’ll focus just on the timing details that are provided.

Step One
create a new file, curl-format.txt, and paste in:
time_namelookup:  %{time_namelookup}\n
       time_connect:  %{time_connect}\n
    time_appconnect:  %{time_appconnect}\n
   time_pretransfer:  %{time_pretransfer}\n
      time_redirect:  %{time_redirect}\n
 time_starttransfer:  %{time_starttransfer}\n
         time_total:  %{time_total}\n

Step Two
Make the request

curl -w "@curl-format.txt" -o /dev/null -s

What this does:
-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 is the URL we are requesting

And here is what you get back:
 time_namelookup:  0.001
        time_connect:  0.037
   time_appconnect:  0.000
    time_pretransfer:  0.037
         time_redirect:  0.000
  time_starttransfer:  0.092
              time_total:  0.164

Timing details include DNS lookup, TCP connect, pre-transfer negotiations, redirects (in this case there were none), and of course the total time.

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