mirror of
https://github.com/jaygooby/ttfb.sh
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100 lines
3.6 KiB
Markdown
100 lines
3.6 KiB
Markdown
# Introduction
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Measures [time-to-first-byte](https://en.wikipedia.org/wiki/Time_to_first_byte) for single or multiple URLs. Can calculate min, max & median TTFB values and log all response headers.
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```
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Usage: ttfb [options] url [url...]
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-d debug
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-l <log file> (infers -d)
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-n number of times to test
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```
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Uses the calculation `%{time_starttransfer¹} - %{time_appconnect²}` which doesn't include any connection overhead, to better approximate devtool’s TTFB figure.
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¹ [`time_starttransfer`](https://github.com/curl/curl/blob/e431daf013ea04cb1a988a2009d820224ef5fb79/docs/cmdline-opts/write-out.d#L141-L144)
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> 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.</blockquote>
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² [`time_appconnect`](https://github.com/curl/curl/blob/e431daf013ea04cb1a988a2009d820224ef5fb79/docs/cmdline-opts/write-out.d#L118-L120)
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>The time, in seconds, it took from the start until the SSL/SSH/etc
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connect/handshake to the remote host was completed.
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# Genesis
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Based on a gist https://gist.github.com/sandeepraju/1f5fbdbdd89551ba7925abe2645f92b5
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by https://github.com/sandeepraju
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Modified by jay@gooby.org, [@jaygooby](https://twitter.com/jaygooby)
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# Usage
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```
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Usage: ttfb [options] url [url...]
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-d debug
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-l <log file> (infers -d)
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-n number of times to test
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```
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Examples:
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```
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$ ttfb example.com
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DNS lookup: 0.523402 TLS handshake: 0.000000 TTFB including connection: 0.692724 TTFB: .692724 Total time: 0.693508
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```
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```
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$ ttfb -n 5 example.com
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min .203970 max .181486 median .190033
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```
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```
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$ ttfb -n 5 bbc.co.uk news.bbc.co.uk
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bbc.co.uk min .032791 max .039401 median .029214
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news.bbc.co.uk min .032927 max .032237 median .037458
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```
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```
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$ ttfb bbc.co.uk news.bbc.co.uk
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bbc.co.uk DNS lookup: 0.005291 TLS handshake: 0.089403 TTFB including connection: 0.119651 TTFB: .030248 Total time: 0.506010
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news.bbc.co.uk DNS lookup: 0.004266 TLS handshake: 0.077179 TTFB including connection: 0.110649 TTFB: .033470 Total time: 0.598472
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```
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Implicitly follows redirects using curl's `-L`
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Log all response headers (default log file is `curl.log`) by calling with `-d`
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Override the default log file by specifying `-l /some/file`
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Get min, max and median values by specifying the number of times to call
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the URL (`-n2` etc)
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If you specify more than one url and have specified `-d` or `-l` the log file
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will be prefixed with the URL being requested.
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```
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$ ttfb -d bbc.co.uk news.bbc.co.uk
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bbc.co.uk DNS lookup: 0.005309 TLS handshake: 0.074216 TTFB including connection: 0.106453 TTFB: .032237 Total time: 0.462894
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news.bbc.co.uk DNS lookup: 0.005355 TLS handshake: 5.358041 TTFB including connection: 5.397377 TTFB: .039336 Total time: 6.013918
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$ ls
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bbc_co_uk-curl.log news_bbc_co_uk-curl.log
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```
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See https://blog.cloudflare.com/a-question-of-timing/
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and https://curl.haxx.se/docs/manpage.html for an explanation
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of how the curl variables relate to the various stages of
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the transfer.
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To get a better approximation of devtool's TTFB, we consider
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the time without the connection overhead:
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`%{time_starttransfer} - %{time_appconnect}`
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Uses a dirty `eval` to do the ttfb arithmetic. Depends
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on `bc` and `column` commands.
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# TODO
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* [ ] Sort output by fastest TTFB when multiple URLs are supplied
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* [ ] Colour code the `TTFB:` figure in the standard response, according to the speed of the response.
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