Check if there are any BackupPC host backups that haven't been copied with rsync.

check_backuppc_pc_dirs.sh

#!/bin/bash

PC_DIR="/var/lib/backuppc/pc"
REMOTE_SERVER=$1
SSH_PORT=$2

# SSH to a remote server to run the specified command
remote () {
        ssh -p $SSH_PORT root@$REMOTE_SERVER "$@"
}

# Return true if the specified remote directory exists
check_exists () {
        if remote test -d "$1"
        then
                return 0
        else
                return 1
        fi
}

# Loop through all the BackupPC hosts
for DIR in `ls $PC_DIR/`
        do
        # Loop through each full and incremental backup directory for a host
        for HOST_DIR in `ls -vd $PC_DIR/$DIR/[0-9]*/`
                do
                # Do a sync if a directory exists locally but not on the remote server
                if ! check_exists "$HOST_DIR"
                then
                        echo $HOST_DIR
                fi
        done
done

Old code I used for a while to test rsyncs before I was using @alexclifford/backuppc-sync.