Bash script to snapshot nuchain db use hardlink & 7z

nuchain-snapshot.sh

#!/usr/bin/env bash

SRCDIR=$1
DSTDIR=$2

show_usage(){
        echo "Usage: nuchain-snapshot [SRCDIR] [DSTDIR]"
        echo "Example: nuchain-snapshot /data/nuchain nuchain-snapshot"
}

do_snapshot(){
        echo "Starting snapshot..."
        rsync -avr --link-dest=$SRCDIR --exclude=keystore --exclude=network $SRCDIR/ $DSTDIR
        7z a -t7z -m0=lzma -mx=9 -mfb=64 -md=32m -ms=on $DSTDIR-$(date +"%Y-%m-%d").7z $DSTDIR
        echo "Done."
}

if [ -z "$SRCDIR" ] || [ -z "$DSTDIR" ]; then
        show_usage
        exit 0
fi

echo SRCDIR=$SRCDIR
echo DSTDIR=$DSTDIR
echo ""

[ ! -d "$SRCDIR" ] && echo "[ERROR] Directory SRCDIR=$SRCDIR not exists" && exit 1
[ -d "$DSTDIR" ] && echo "[ERROR] Directory DSTDIR=$DSTDIR already exists" && exit 2

if [ "$3" == "--yes" ]; then
        echo "Skip confirmation"
        do_snapshot
else
        echo "Will execute this:"
        echo  '>'  rsync -avr --link-dest=$SRCDIR --exclude=keystore --exclude=network $SRCDIR/ $DSTDIR
        echo  '>'  7z a -t7z -m0=lzma -mx=9 -mfb=64 -md=32m -ms=on $DSTDIR-$(date +"%Y-%m-%d").7z $DSTDIR
        read -p "Are you sure? [y/n] " yn

        if [[ "$yn" =~ "y" ]]; then
                do_snapshot
        fi
fi