Just to give another option, you can use systemd to achieve crontab-like functionality and on most systems that would be the more modern way to do it.
/etc/systemd/system/rclone-sync.service:
[Unit]
Description=Sync files between different remotes via rclone
[Service]
Type=simple
ExecStart=/usr/bin/rclone-sync
/etc/systemd/system/rclone-sync.timer:
[Unit]
Description=Perform an rclone sync periodically.
[Timer]
OnBootSec=1h
OnUnitActiveSec=3h
[Install]
WantedBy=timers.target
/usr/bin/rclone-sync:
rclone sync acd: gdrive:
In this simple example you could just replace ExecStart=/usr/bin/rclone-sync with ExecStart=/usr/bin/rclone sync acd: gdrive:
But since the rclone command can get pretty convoluted, or you might want to do some pre- and post-processing, i personally prefer to just call a script.
Enable with
systemctl enable rclone-sync.timer
systemctl start rclone-sync.timer
Monitor via the usual systemd commands, e.g.:
systemctl list-timers
journalctl -u rclone-sync -a
You can configure the timer so that the service will be continuously running but i don’t think that’s the best idea. just set the timer to a couple of minutes, if you really need high frequency updates.