Latency percentile

ttfb.sh

#!/bin/bash

# ntimes: https://github.com/yuya-takeyama/ntimes - or `repeat` if using zsh
# percentile: https://github.com/yuya-takeyama/percentile

# usage: ttfb URL [TIMES] | percentile

TIMES=${2:-100}

(ntimes $TIMES -- \
curl $1 \
  -H 'pragma: no-cache' \
  -H 'cache-control: no-cache' \
  -H 'accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9' \
  -H 'accept-language: en-US,en;q=0.9,pt-BR;q=0.8,pt;q=0.7' \
  --compressed -s -o /dev/null -w "%{time_starttransfer}\n" | sed "s/\,/\./") | percentile
  
# Results:
# ❯ ./ttfb.sh https://site.gympass.com 1000
# 50%:	0.120782
# 66%:	0.123328
# 75%:	0.124996
# 80%:	0.125849
# 90%:	0.129709
# 95%:	0.134144
# 98%:	0.141621
# 99%:	0.154519
# 100%:	0.632481