zlacker

oh boy... -b takes an option which in your examples is -A and -e, then what follows is interpreted as a URL and you throw away the warnings:

  % curl -vgsSIw'> %{time_total}\n' -b -A "curl/8.2.1" https://t.co/DzIiCFp7Ti 2>&1 | grep '^\(* WARNING: \)\|\(Could not resolve host: \)\|>' 
  * WARNING: failed to open cookie file "-A"
  * Could not resolve host: curl
  curl: (6) Could not resolve host: curl
  * WARNING: failed to open cookie file "-A"
  > HEAD /DzIiCFp7Ti HTTP/2
  > Host: t.co
  > User-Agent: curl/8.1.2
  > Accept: */*
  > 
  > 0.013309
  > 0.112494

>>mzs+(OP)
Alright thanks for explaining that . Here's what I see explicitly setting the cookiejar

    $ time curl -s -b cookies.txt -c cookies.txt -A "Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Firefox/102.0" -e ";auto" -L https://t.co/DzIiCFp7Ti

    [t.co meta refresh page src]

    real     0m4.635s
    user   0m0.004s
    sys     0m0.008s

    $ time curl -b cookies.txt -c cookies.txt -A "wget/1.23" -e ";auto" -L https://t.co/DzIiCFp7Ti                        curl: (7)
    Failed to connect to www.threads.net port 443:  Connection refused
    real     0m4.635s
    user   0m0.011s
    sys     0m0.005s

    $ time curl -b cookies.txt -c cookies.txt -e ";auto" -L https://t.co/DzIiCFp7Ti                                       curl: (7)
    Failed to connect to www.threads.net port 443 Connection refused
    real     0m0.129s
    user   0m0.000s
    sys     0m0.013s

The failed to connects are threads.net likely blocking those user agents but the timing is there which is different than the first UA attempt.