Split array into groups of three instead of groups of two

July 14, 2022

Currently I have this backup script working just fine in Unraid.
I can add as many backup jobs to the array below as I like and the script will loop through these one after the other until all are done.

#!/bin/bash

# backup source to destination
backup_jobs=(
# source                         # destination
"/mnt/user/isos"                 "/mnt/disks/Backup"
"/mnt/user/data"               "/mnt/disks/Backup"
)

# loop through all backup jobs
for i in "${!backup_jobs[@]}"; do

    # get source path and skip to next element
    ! (( i % 2 )) && src_path="${backup_jobs[i]}" && continue

    # get destination path
    dst_path="${backup_jobs[i]}"
    
    #run backup
    rsync -av --delete --log-file=/mnt/disks/Backup/rsync-logs/log.`date '+%Y_%m_%d__%H_%M_%S'`.log --progress --exclude '.Recycle.Bin' "$src_path" "$dst_path"

Now I would like to also have a subfolder for the rsync-logs per backup job.

For that I’d like to add a name to the array for each job – but I cannot figure out how to get the loop to load that 3rd variable per line per loop like the other 2 variables.
🙁

backup_jobs=(
    # source                    # destination         # jobname
    "/mnt/user/isos"            "/mnt/disks/Backup"   "isos"
    "/mnt/user/data"            "/mnt/disks/Backup"   "backup"
    )

Anyone able to help? 🙂

>Solution :

Use i % 3 instead of i % 2. This will be 0 for the source path, 1 for the destination path, and 2 for the job name.

for i in "${!backup_jobs[@]}"; do
    case $(($i % 3)) in
        0) src_path="${backup_jobs[i]}"; continue ;;
        1) dst_path="${backup_jobs[i]}"; continue ;;
        2) job_name="${backup_jobs[i]}" ;;
    esac
    
    #run backup
    rsync -av --delete --log-file=/mnt/disks/Backup/rsync-logs/"$job_name"/log.`date '+%Y_%m_%d__%H_%M_%S'`.log --progress --exclude '.Recycle.Bin' "$src_path" "$dst_path"
done