disable any mastodon users not active for the past 7890000 seconds (91.3 days)

disable_inactive_mastodon_users.sh

#!/bin/bash

DB_HOST=1.2.3.4
DB_PORT=5432
DB_NAME=mastodon_production
DB_USER=mastodon

PGPASSWORD=yourpassword psql -h ${DB_HOST} -p ${DB_PORT} -d ${DB_NAME} -U ${DB_USER} -w -1 -t -A -F" " -c "SELECT accounts.username, TRUNC(EXTRACT(EPOCH FROM (NOW() - current_sign_in_at))) AS diff FROM users JOIN accounts ON users.account_id = accounts.id WHERE (approved = TRUE AND disabled = FALSE)" | while read -r user time;
do
    if [[ -v user && time -ge 7890000 ]]; then
            RAILS_ENV='production' /home/mastodon/live/bin/tootctl accounts modify $user --disable
            echo "$user SUSPENDED for exceeding 7 890 000 seconds"
    else
            echo "$user is OK!"
    fi
done

I don't think you have to bother with the time comparison in the shell script, let the DB do the heavy lifting:

SELECT accounts.username FROM users JOIN accounts ON users.account_id = accounts.id WHERE (approved = TRUE AND disabled = FALSE AND current_sign_in_at < NOW() - INTERVAL '90 days');

@SISheogorath good idea, almost certainly scales a lot better. In our case the size of the instance is minimal though.