In addition to Admin/changeme, a generic read-only username/password (e.g. box/box) is also necessary...unless we (@darkenvy?) also get calibre-web front-end to work (#816) !

1. Create the users/passwords in /library/calibre/users.sqlite by running:

systemctl stop calibre-serve
calibre-server --manage-users --userdb /library/calibre/users.sqlite

2. Remember to remove read/write permissions from student accounts like box/box or mx/mx etc, using:

2. Edit an existing user
3. Change read/write permission for [ACTUAL ACCOUNT NAME]

3. Unit file /etc/systemd/system/calibre-serve.service must contain:

ExecStart=/usr/bin/calibre-server --daemonize --log=/var/log/calibre.log --pidfile=/var/run/calibre.pid --port=8080 --enable-auth --userdb=/library/calibre/users.sqlite /library/calibre

4. Should be obvious, but before testing http://box:8080 you need to have run:

systemctl daemon-reload
systemctl start calibre-serve

5. Also remember that most browsers REMEMBER Calibre's username/password. So you need to fully close your browser AND forcefully flush cached password(s) from your browser, if changing to/from teacher credential (typically Admin/changeme) from/to student credential (typically box/box or mx/mx or whatever...)