follower_posts.sh

#!/bin/bash

while getopts u: flag
do
    case "${flag}" in
        u) user=${OPTARG};;
        *) echo "Bailing out."; exit 1
    esac
done

if [ -z "$user" ]; then
    echo "The -u (user) flag is required, formatted as username@domain.tld"; exit 1
fi

domain=$(echo $user | cut -d '@' -f 2)
user_id=$(curl --max-time 10 --connect-timeout 5 -s "https://${domain}/api/v2/search?q=${user}" | jq -r '.accounts[0].id')

if [ $? -ne 0 ] || [ -z "$user_id" ] || [ "$user_id" == "null" ]; then
    echo "User ID not found for $user."; exit 1
fi

followings=""
api_endpoint="https://$domain/api/v1/accounts/$user_id/following?limit=80"
tmp_headers="headers-$(date +%s).txt"
while [ ! -z "$api_endpoint" ]; do
    response=$(curl --max-time 10 --connect-timeout 5 -s -D "$tmp_headers" "$api_endpoint")
    followings_iter=$(echo "$response" | jq -r '.[] | .acct') # this iteration
    followings=$(echo -e "${followings}\n${followings_iter}") # append to total
    next_link=$(grep -oP '(?<=<).*(?=>; rel="next")' "${tmp_headers}")
    if [ ! -z "$next_link" ]; then
        api_endpoint="$next_link" # move on to the next page
    else
        api_endpoint="" # no next link, we're done
        rm headers-*.txt
    fi
done

if [ "$followings" != "" ]; then
    follow_count=$(echo "$followings" | grep -c -v '^$')
    echo "$user is following ${follow_count} accounts."
fi

echo "Now querying instances for last post dates, please wait."
output=""
failed_accounts=""
failed_count=0
current_time=$(date -u +%s)
for acct in $followings
do
    full_acct="$acct" # might be needed to allow override, dunno
    if [[ $full_acct != *"@"* ]]; then # local name is missing @instance
        acct_instance=$domain
        full_acct="${acct}@${domain}"
    else
        acct_instance=$(echo $acct | cut -d '@' -f 2)
    fi
    remote_user_id=$(curl --max-time 10 --connect-timeout 5 -s "https://$acct_instance/api/v2/search?q=$full_acct" | jq -r '.accounts[0].id' 2>/dev/null)
    if [ $? -ne 0 ] || [ -z "$remote_user_id" ] || [ "$remote_user_id" == "null" ]; then
        failed_accounts+="${full_acct}\n"
        ((failed_count++)); continue
    fi
    last_post=$(curl --max-time 10 --connect-timeout 5 -s "https://$acct_instance/api/v1/accounts/$remote_user_id/statuses" | jq -r '.[0].created_at' 2>/dev/null)
    if [ $? -ne 0 ] || [ -z "$last_post" ] || [ "$last_post" == "null" ]; then
        failed_accounts+="$full_acct\n"
        ((failed_count++)); continue
    fi
    last_post_epoch="$(date -u -d "$last_post" +%s)"
    last_post_diff=$((current_time - last_post_epoch))
    days_since=$((last_post_diff / 86400))
    output+="$last_post $full_acct (${days_since}d ago)\n"
done
echo "************************************************************"
echo "*          last post for accounts (oldest first)           *"
echo "************************************************************"
echo -e "$output" | sort
echo -e "\n************************************************************"
echo -e "\n${failed_count} accounts failed.\n"
echo "Possible reasons: the account is private, the instance"
echo "does not support the required Mastodon API endpoints,"
echo "the account has no posts or connection timed out."
for i in $failed_accounts; do echo -e "\n${i}"; done
echo -e "************************************************************"

TODO: Just realized this doesn't work as expected since the mastodon API is paged when fetching all followers.
fixed!