Month: January 2019

Introduction

MacOS has a good backup system which allows you to recover any files that have beed deleted or to restore previous versions of the files. I works like you can literally come back into a certain moment back in time.

Now that I have set up Raspberry Pi based home NAS, I found a solution that achieves the same results on linux: incrental backups with rsync.

Instruction: how to automate backups on Linux

Step 1. Set up rsync backup script, with instructions and settings on how to run the backup

sudo mkdir /usr/local/scripts      #to make folder to store scripts
sudo touch /usr/local/scripts/backup.sh # to create the script
sudo chmod +x  /usr/local/scripts/backup.sh  # make it executable
sudo nano /usr/local/scripts/backup.sh  #THEN EDIT THE SCRIPT:

Copy this code into the script:

# This script makes backups from DATADIR to BACKUPDIR and puts in 
# date-named folders corresponding to date of each backup
# SYNTAX:  $ ./backup.sh </DATADIR/ ($1)> </BACKUPDIR/ ($2)>
# Example: $ ./backup.sh /media/data/ /media/backup/

# To be able to use CTRL+C to exit script:
trap "exit" INT 

# Define the directories for backup
DATA=$1
LAST_BACKUP_PATH=$2/$(ls $2 | tail -n 1)
THIS_BACKUP_PATH=$2/backup_in_progress

# Make the backup
rsync -av --link-dest ${LAST_BACKUP_PATH} ${DATA} ${THIS_BACKUP_PATH}

# Move the backup to date-named folder after it's finished
mv $2/backup_in_progress $2$(date +%Y-%m-%d)

Step 2. Set up cron job to run the backup script on a schedule

sudo crontab -e

To backup DATA_DIR to BACKUP_DIR at 3am every night, add this to your cron file:

# BACKUP SCRITPS
# WHEN       SCRIPT DIR                    DATA_DIR     BACKUP_DIR
  0 4 1 * *  /usr/local/scripts/backup.sh  /data/dir/  /backup/dir
  0 3 * * *  /usr/local/scripts/backup.sh  /data2/dir/ /backup2/dir
# - - - - -  CRON SYNTAX explained below:
# | | | | |
# | | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
# | | | ------- Month (1 - 12)
# | | --------- Day of month (1 - 31)
# | ----------- Hour (0 - 23)
# ------------- Minute (0 - 59)

Useful Links

More on cron read here, or crontab calculator here

Bash scripts 101

https://linuxconfig.org/how-to-create-incremental-backups-using-rsync-on-linux

http://www.mikerubel.org/computers/rsync_snapshots/

https://stackoverflow.com/questions/13778889/rsync-difference-between-size-only-and-ignore-times

https://unix.stackexchange.com/questions/102211/rsync-ignore-owner-group-time-and-perms