Curl-ttfb/README.md

Introduction

Measures time-to-first-byte for single or multiple URLs. Can calculate min, max & median TTFB values and log all response headers.

Usage: ttfb [options] url [url...]
  -d debug
  -l <log file> (infers -d)
  -n number of times to test

Uses the calculation %{time_starttransfer¹} - %{time_appconnect²} which doesn't include any connection overhead, to better approximate devtool’s TTFB figure.

¹ 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.

² time_appconnect

The time, in seconds, it took from the start until the SSL/SSH/etc connect/handshake to the remote host was completed.

Genesis

Based on a gist https://gist.github.com/sandeepraju/1f5fbdbdd89551ba7925abe2645f92b5 by https://github.com/sandeepraju

Modified by jay@gooby.org, @jaygooby

Usage

Usage: ttfb [options] url [url...]
  -d debug
  -l <log file> (infers -d)
  -n number of times to test

Examples:

$ ttfb example.com
DNS lookup: 0.523402 TLS handshake: 0.000000 TTFB including connection: 692724 TTFB: .692724 Total time: 0.693508

$ ttfb -n 5 example.com
min .203970 max .181486 median .190033

$ ttfb -n 5 bbc.co.uk news.bbc.co.uk
bbc.co.uk       min .032791 max .039401 median .029214
news.bbc.co.uk  min .032927 max .032237 median .037458

$ ttfb bbc.co.uk news.bbc.co.uk
bbc.co.uk        DNS lookup: 0.005291 TLS handshake: 0.089403 TTFB including connection: 0.119651 TTFB: .030248 Total time: 0.506010
news.bbc.co.uk   DNS lookup: 0.004266 TLS handshake: 0.077179 TTFB including connection: 0.110649 TTFB: .033470 Total time: 0.598472

Implicitly follows redirects using curl's -L

Log all response headers (default log file is curl.log) by calling with -d

Override the default log file by specifying -l /some/file

Get min, max and median values by specifying the number of times to call the URL (-n2 etc)

If you specify more than one url and have specified -d or -l the log file will be prefixed with the URL being requested.

$ ttfb -d bbc.co.uk news.bbc.co.uk
bbc.co.uk        DNS lookup: 0.005309 TLS handshake: 0.074216 TTFB including connection: 0.106453 TTFB: .032237 Total time: 0.462894
news.bbc.co.uk   DNS lookup: 0.005355 TLS handshake: 5.358041 TTFB including connection: 5.397377 TTFB: .039336 Total time: 6.013918

$ ls
bbc_co_uk-curl.log      news_bbc_co_uk-curl.log

See https://blog.cloudflare.com/a-question-of-timing/ and https://curl.haxx.se/docs/manpage.html for an explanation of how the curl variables relate to the various stages of the transfer.

To get a better approximation of devtool's TTFB, we consider the time without the connection overhead: %{time_starttransfer} - %{time_appconnect}

Uses a dirty eval to do the ttfb arithmetic. Depends on bc and column commands.

TODO

• Sort output by fasted TTFB when multiple URLs are supplied

• Colour code the TTFB: figure in the standard response, according to the speed of the response.