Make backups and clean up old ones using the grandfather-father-son principle

backup.sh

#!/bin/bash
# Make backups and clean up old ones using the grandfather-father-son principle
#
# Keeps one backup per four weeks ( roughly one per month ) for a year
#                  per week for four weeks
#                  per day for one week
#
# DRYRUN="yes" BACKUP_CONTEXT="/home/user" backup.sh BACKUP_SRC BACKUP_DEST
#
# DRYRUN: when set nothing is actually done, useful for testing
# BACKUP_CONTEXT: when set passes the variable to tar -C <>
#
# Required:
# BACKUP_SRC: path to back up, absolute, or relative to the current dir or $BACKUP_CONTEXT
# BACKUP_DEST: rclone specifier of where to put the backup: <remote>:<bucket>/<path>

set -o pipefail

BACKUP_NAME=${BACKUP_NAME:-"backup"}

backup_src="$1"
backup_dest="$2"

backup_ident=$(date +"%Y_%m_%d_%V_%u")

current_week=$(date +"%V")
current_year=$(date +"%Y")
current_quarter=$(date +"%q")

tmpdir=${TMPDIR:-"/tmp"}

do_backup() {
    echo "making backup: ${BACKUP_NAME}_${backup_ident}"
    if [ -z "$DRYRUN" ]; then
        if [ -z "$BACKUP_CONTEXT" ]; then
            tar -czf "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" -C "$BACKUP_CONTEXT" "$backup_src"
        else
            tar -czf "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" "$backup_src"
        fi
        rclone copy "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" "$backup_dest"
        rm "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz"
    fi
}

list_backups() {
    rclone lsf "${backup_dest}"
}

get_components() {
    __SRC="$1"
    __SRC="${__SRC##${BACKUP_NAME}_}"
    __SRC="${__SRC%%.tar.gz}"

    while IFS='_' read -ra COMP; do
         WEEK="${COMP[3]}"
         DAY_OF_WEEK="${COMP[4]}"
         YEAR="${COMP[0]}"
    done <<< "${__SRC}"
}

quarter() {
    if [[ "$1" < "14" ]]; then
        echo 1
    elif (( $1 < 27 )); then
        echo 2
    elif (( $1 < 40 )); then
        echo 3
    else
        echo 4
    fi
}

delete_backup() {
    echo "$1"
    if [ -z "$DRYRUN" ]; then
        rclone deletefile "${backup_dest}/$1"
    fi
}

# Weeks to keep
# 04 08 12 16 20 24 28 32 36 40 44 48 52
#
# 01  02  03 |04  05  06  07 |08  09  10  11 |12  13
# 14  15 |16  17  18  19 |20  21  22  23 |24  25  26
# 27 |28  29  30  31 |32  33  34  35 |36  37  38  39
# |40 41  42  43 |44  45  46  47 |48  49  50  51 |52
#
weeks="04 08 12 16 20 24 28 32 36 40 44 48 52"

clean_backups() {
    backups="$(list_backups)"

    for backup in $backups; do
        get_components "$backup"


        if [[ "$YEAR" == "$current_year" ]]; then
            if [[ "$WEEK" == "$current_week" ]]; then continue; fi

            if [[ $DAY_OF_WEEK != 1 ]]; then
                delete_backup "$backup"
                continue
            fi

            if [[ $WEEK < $((current_week - 4)) ]]; then
                if [[ "$weeks" != *"$WEEK"* ]]; then
                    delete_backup "$backup"
                fi

                if [[ "$(quarter $WEEK)" < "$((current_quarter - 2))" ]]; then
                    if [[ "04 16 28 40" != *"$WEEK"* ]]; then
                        delete_backup "$backup"
                    fi
                fi
            fi
        elif [[ "$YEAR" == "$((current_year - 1))" ]]; then
            if [[ $DAY_OF_WEEK != 1 ]]; then
                delete_backup "$backup"
                continue
            fi

            if [[ "$(quarter $WEEK)" > "$((current_quarter - 1))" ]]; then
                if [[ "04 16 28 40" != *"$WEEK"* ]]; then
                    delete_backup "$backup"
                fi
            else
                delete_backup "$backup"
            fi
        else
do_backup() {
    echo "making backup: ${BACKUP_NAME}_${backup_ident}"
    if [ -z "$DRYRUN" ]; then
        if [ -z "$BACKUP_CONTEXT" ]; then
            tar -czvf "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" -C "$BACKUP_CONTEXT" "$backup_src"
        else
            tar -czvf "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" "$backup_src"
        fi
        rclone copy "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz" "$backup_dest"
        rm "${tmpdir}/${BACKUP_NAME}_${backup_ident}.tar.gz"
    fi
}

            delete_backup "$backup"
        fi
    done
}

do_backup
clean_backups