get the unix timestamps (seconds since start of epoch) for every commit in phylesystem-1 that changes the # of studies

num-studies-in-phylesystem.bash

#!/bin/bash
git rev-list HEAD > commits.txt
prev_ns=0
for sha in $(cat commits.txt)
do
    unix_time=$(git show -s --format=%at "${sha}")
    git checkout $sha || exit
    num_studies=$(find study -name "*.json" | wc -l)
    if test $num_studies -ne $prev_ns
    then
        echo $unix_time $num_studies
    fi
    prev_ns=$num_studies
done