Minecraft Saves Backup Manager (can be used for other stuff as well)

mcbackup.sh

#!/bin/bash
set -e

help_text='
McBackup creates and manages backups of your Minecraft game saves.

Game saves are expected to be stored in ~/.minecraft/saves.
Backups are stored in ~/.minecraft/backups by default.
To change this edit the $mcdir and $backupdir variables.

McBackup will manage multiple copies of varying age of each game save.
Old backups will be discarded incrementally.

Usage:
/path/to/mcbackup.sh [OPTIONS] [SAVES]

OPTIONS See below
SAVES   Can be a list of names of game saves to be backed up.
        May be omitted if the -a option is used (see below).
        The name of the directory inside $mcdir/saves/ is relevant.
        Note that this may not be identical to the name displayed in-game.
        Saves that do not have a corresponding directory inside the
        $backupdir/ will be skipped unless the -f switch is specified.
        

Options:
    -a  Backup all saves that are inside $mcdir/saves/.
        If used with -d, process all backups inside $backupdir/
        (regardless of whether they exist inside $mcdir/saves/)
    
    -d  Discard only. Do not create new backups but check existing ones for
        obsolete versions
        
    -f  Force backup creation. If a save does not have a corresponding
        directory inside $backupdir/ that directory will be created.
        
    -h  Show this help text and exit.
    
    -n  No discarding. Only create backups, do not check if any are outdated.

Created by Gandalfx
https://gandalfx.github.com
'


################
### settings ###
################
mcdir="$HOME/.minecraft"
backupdir="$HOME/.minecraft/backups"


#################
### functions ###
#################

# creates a new backup if possible and necessary
# param 1 is save's (base)name
function update_backup {
    
    local save="$(basename "$1")"
    if [[ ! -d "$mcdir/saves/$save" ]] ; then
        echo "skipping '$save'..."
        return
    fi
    
    echo -en "checking $bold$blue$save$end: "
    
    if [[ ! -d "$backupdir/$save" ]] ; then
        if $flag_force ; then
            echo -e "${green}creating backup at '$backupdir/$save'..."
            mkdir -p "$backupdir/$save"
        else
            echo -e "$red'$backupdir/$save' doesn't exist!$end skipping..."
            return
        fi
    fi
    
    if [ ! -e "$backupdir/$save/latest" ] ||
        [[ $(diff -rq "$mcdir/saves/$save" "$backupdir/$save/latest") != "" ]]
    then
        echo -e "${red}backup outdated!$end"
        local today=$(date +%F)
        echo "syncing files..."
        rsync -a --delete "$mcdir/saves/$save/" "$backupdir/$save/$today"
        ln -snf "$backupdir/$save/$today" "$backupdir/$save/latest"
        
        $flag_no_discard || discard_old_backups "$backupdir/$save"
        
    else
        echo -e "${green}up to date$end"
    fi
}


# manages old saves
# param 1 is path containing saves
function discard_old_backups {
    pushd . > /dev/null
    cd "$1"
    
    local saves=(*-*-*)         # format is yyyy-mm-dd
    unset saves[${#saves[@]}-1] # always keep youngest save
    unset days week month year  # steps
    
    for save in "${saves[@]}" ; do
        # echo "found save $save"
        
        if [[ $save < $(date +%F -d "1 year ago") ]] ; then
            # $save is older then a year
            # -> keep youngest
            if [[ $year ]] ; then
                rm -r $year
                echo "removed old save '$PWD/$year'"
            fi
            local year=$save
        
        elif [[ $save < $(date +%F -d "1 month ago") ]] ; then
            # $save is older then a month but younger then a year
            # -> keep oldest
            if [[ $month ]] ; then
                rm -r $save
                echo "removed old save '$PWD/$save'"
            else
                local month=$save
            fi
        
        elif [[ $save < $(date +%F -d "1 week ago") ]] ; then
            # $save is older then a week but younger then a month
            # -> keep oldest
            if [[ $week ]] ; then
                rm -r $save
                echo "removed old save '$PWD/$save'"
            else
                local week=$save
            fi
        
        elif [[ $save < $(date +%F -d "2 days ago") ]] ; then
            # $save is older then 2 days but younger then a week
            # -> keep oldest
            if [[ $days ]] ; then
                rm -r $save
                echo "removed old save '$PWD/$save'"
            else
                local days=$save
            fi
        fi
    done
    
    popd > /dev/null
}


###########
### run ###
###########

# use colors only for terminal output
if [[ -t 1 ]] ; then
    red="\e[91m"
    blue="\e[34m"
    green="\e[32m"
    bold="\e[1m"
    end="\e[0m"
fi

# parse flags
flag_all=false
flag_force=false
flag_no_discard=false
flag_discard_only=false
while getopts "afndh" opt ; do
    case "$opt" in
        a) flag_all=true;;
        f) flag_force=true;;
        n) flag_no_discard=true;;
        d) flag_discard_only=true;;
        h) printf "$help_text"; exit;;
        *) exit 1;;
    esac
done
# remove flags from parameter list
shift $(($OPTIND - 1))


if $flag_discard_only ; then
    $flag_all && saves=( "$backupdir/"* ) || saves=( $@ )
    [[ $saves ]] || echo "no saves specified!"
    
    for save in "${saves[@]}" ; do
        save="$(basename "$save")"
        if [[ -d "$backupdir/$save" ]] ; then
            discard_old_backups "$backupdir/$save"
        else
            echo "'$save' has no backups."
        fi
    done
    
else
    $flag_all && saves=( "$mcdir/saves/"* ) || saves=( $@ )
    [[ $saves ]] || echo "no saves specified!"
    
    for save in "${saves[@]}" ; do
        update_backup "$save"
    done
fi


### an old friend
# for age in saves_2*; do for sav in $age/* ; do mkdir -pv "backups/$(basename "$sav")" && cp -ru "$sav" "backups/$(basename "$sav")/${age#saves_}"; done; done