Nsryjdtyk

I want your suggestions about this script. I use it to backup configuration of softwares installed on my home media server.

What improvements would you do?

thanks you for any inputs.

#!/bin/bash



# ==================================================================================

# Description:  BackUp script following a Hanoi scheme using rsync.

# Author:       Hugo Lapointe Di Giacomo

# ==================================================================================



set -o errexit

set -o nounset

#set -o xtrace



# ----------------------------------------------------------------------------------

# Options

# ----------------------------------------------------------------------------------

setsMax=16 # ................................ Maximum number of sets bakcup.

cmdPrefix="" # .............................. "echo" if dry-run enable, "" otherwise.

srcDir="/appdata" # ......................... Source directory to backup.

dstDir="/mnt/backup/snapshots" # ............ Destination directory to backup in.

logDir="/mnt/backup/logs" # ................. Logs directory.





# ----------------------------------------------------------------------------------

# Constants

# ----------------------------------------------------------------------------------

SEC_PER_DAY=86400; # ........................ Number of seconds per day.

LATEST_SNAP="$dstDir/latest"; # ............. The "latest" snap.

LATEST_LOG="$logDir/latest"; # .............. The "latest" log.

DATE_FORMAT="%Y-%m-%d"; # ................... The format of a date.

HOUR_FORMAT="%H:%M"; # ...................... The format of a hour.





# ----------------------------------------------------------------------------------

# Show usage of this script.

# ----------------------------------------------------------------------------------

function showUsage() {

    echo "Usage: $0 [OPTIONS]..."

    echo ""

    echo "Options available:"

    echo " -h, --help   Show usage of the script."

    echo " -m, --max    Maximum sets of backup."

    echo " -s, --src    Source directory to backup."

    echo " -d. --dst    Destination directory to backup in."

    echo " -l, --log    Log directory."

    echo " -r, --dry    Enable dry-run."

}





# ----------------------------------------------------------------------------------

# Parse arguments.

# ----------------------------------------------------------------------------------

function parseArgs() {

    while [ $# -gt 0 ]; do

        case $1 in

            -h|--help)

                showUsage $@

                exit 0

            ;;



            -m|--max)

                setsMax=${2:-$setsMax}

                shift 2

            ;;



            -s|--src)

                if [ -d "$2" ]; then

                    srcDir="$2"

                fi

                shift 2

            ;;



            -d|--dst)

                if [ -d "$2" ]; then

                    dstDir="$2"

                fi

                shift 2

            ;;



            -l|--log)

                if [ -d "$2" ]; then

                    logDir="$2"

                fi

                shift 2

            ;;



            -r|--dry)

                cmdPrefix="echo"

                shift 1

            ;;



            *)

                echo "Unknown option or value: $1"

                showUsage $@

                exit 1

            ;;

        esac

    done

}





# ----------------------------------------------------------------------------------

# Create a backup with rsync.

# ----------------------------------------------------------------------------------

function createBackUp() {   

    snapDir="$dstDir/$1" # ................. Name of the snap dir.

    logFile="$logDir/$1.log" # ............. Name of the log file.



    RSYNC_CMD="rsync " # ................... Rsync Command.

    RSYNC_CMD+="--archive " # .............. Enable recursion and preserve infos.

    RSYNC_CMD+="--verbose " # .............. Increase amount of infos printed.

    RSYNC_CMD+="--human-readable " # ....... Output number in readable format.

    RSYNC_CMD+="--progress " # ............. Show progress during transfer.

    RSYNC_CMD+="--delete " # ............... Delete files from receiving side.

    RSYNC_CMD+="--link-dest=$LATEST_SNAP " # "latest" symbolic link to hardlink.

    RSYNC_CMD+="$srcDir " # ................ Source directory to backup.

    RSYNC_CMD+="$snapDir " # ............... Destination directory to backup in.



    # Create backup and save the output in a log file.

    $cmdPrefix $RSYNC_CMD 2>&1 | tee "$logFile"

}



# ----------------------------------------------------------------------------------

# Update the latest links.

# ----------------------------------------------------------------------------------

function updateLatestLinks() {

    $cmdPrefix rm -f "$LATEST_SNAP"

    $cmdPrefix ln -s "$snapDir" "$LATEST_SNAP"



    $cmdPrefix rm -f "$LATEST_LOG"

    $cmdPrefix ln -s "$logFile" "$LATEST_LOG"

}



# ----------------------------------------------------------------------------------

# Calculate the previous move in the cycle.

# https://en.wikipedia.org/wiki/Backup_rotation_scheme

# ----------------------------------------------------------------------------------

function calculateDaysFromBackupOfSameSet() {

    local todayInSec=$(date +%s)

    local todayInDay=$(($todayInSec / $SEC_PER_DAY))



    local daysToBackup=$((2 ** ($setsMax - 1))) 



    local daysElapsed=0

    local i=1



    while [ $i -lt $(($daysToBackup / 2)) ]; do

        local rotation=$(($todayInDay & $i))



        if [ $rotation -eq 0 ]; then

            daysElapsed=$(($i * 2))

            break

        fi



        daysElapsed=$(($daysToBackup / 2))

        i=$((2 * $i))

    done



    echo $daysElapsed

}





# ----------------------------------------------------------------------------------

# Main function.

# ----------------------------------------------------------------------------------

function main() {

    parseArgs $@



    local todayDatetime=$(date +$DATE_FORMAT.$HOUR_FORMAT)



    if createBackUp $todayDatetime; then

        updateLatestLinks



        local daysElapsed=$(calculateDaysFromBackupOfSameSet)

        local expiredDay=$(date -d "$daysElapsed days ago" +$DATE_FORMAT)

        $cmdPrefix rm -frv "$dstDir/$expiredDay."*

    fi

}



main $@