Response times with curl

Creating the uptime Script

First, let’s create a file named uptime and add the following content:

#!/usr/bin/env bash

format=$(cat <<EOF
---------------------------------------------
Uptime of $@ is
---------------------------------------------
      time_namelookup:  %{time_namelookup}s
        time_connect:  %{time_connect}s
     time_appconnect:  %{time_appconnect}s
    time_pretransfer:  %{time_pretransfer}s
       time_redirect:  %{time_redirect}s
  time_starttransfer:  %{time_starttransfer}s
---------------------------------------------
          time_total:  %{time_total}s
EOF
)

curl -w "$format" -o /dev/null -s "$@"

This script defines a format variable that contains a template for the output. The curl command is then used to measure the performance of the specified URL and display the results in the defined format.

Running the Script

chmod +x uptime
uptime https://www.google.com

You should see output similar to the following:

---------------------------------------------
Uptime of https://www.google.com is
---------------------------------------------
      time_namelookup:  0.021137s
        time_connect:  0.033610s
     time_appconnect:  0.064180s
    time_pretransfer:  0.064246s
       time_redirect:  0.000000s
  time_starttransfer:  0.134371s
---------------------------------------------
          time_total:  0.136121s

Explanation of Output:

• time_namelookup: The time it took to resolve the DNS name.
• time_connect: The time it took to establish the connection.
• time_appconnect: The time it took to complete the SSL/TLS handshake (if applicable).
• time_pretransfer: The time from the start until just before the file transfer begins.
• time_redirect: The time spent on redirections (if any).
• time_starttransfer: The time from the start until the first byte is received.
• time_total: The total time for the entire request.

Loading Format from a File

Alternatively, you can store the format in a separate file (e.g., format.txt) and use it with curl:

curl -w "@format.txt" -o /dev/null -s https://www.google.com

Source: StackOverflow