merge

#!/bin/bash

ask() { local q="$1"; local d=${2:-"n"}
  read -p "$q [$d]: " r; r=${r:-"$d"}
  local i=0; while true; do
    case $r in
      y|Y|yes|Yes|yES|YES )
        return 0
        ;;
      n|N|no|No|nO )
        return 1
        ;;
      * )
        i=$((i+1))
        [ $i -le 3 ] && read -p "Not a valid answer. Try 'y' or 'n': " r || exit 1
        continue
        ;;
    esac
  done
}

usage() {
	[ ! -z "$2" ] && echo "Error: $2."
	echo "Usage: $0 -s <path/to/source> -t <path/to/target> [-i -e <backup-extension>]"
	echo "Options:"
	echo -e "\t-i\tOverwrite files without backup."
	echo -e "\t-e\tBackup extension. Default: \"-dpkg\""
	exit $1
}

sync() {
	# copy directory structure
	for d in `find $SRC -type d`; do
		[ $d == "$SRC" ] && continue
		CDIR=$(echo $d | sed "s|$SRC||")
		[ ! -d "$DST$CDIR" ] && echo "Making $CDIR" && mkdir -p "$DST$CDIR"
	done

	# copy files backing up existing
	for f in `find $SRC -type f`; do
		CFILE=$(echo $f | sed "s|$SRC||")
		$BKP && [ -f "$DST$CFILE" ] && echo "Backing up $CFILE to $(basename $CFILE)$EXT" && cp "$DST$CFILE" "$DST$CFILE$EXT"
		echo "Copying $CFILE"
		cp -f "$f" "$DST$CFILE"
	done
}

# get options
BKP=true # Making backups is default.
EXT="-dpkg"
OPTSTR="hs:t:ie:"
while getopts "$OPTSTR" OPT; do
	case "$OPT" in
		h) usage ;;
    s) SRC=$OPTARG ;;
		t) DST=$OPTARG ;;
		i) BKP=false ;;
		e) EXT=$OPTARG ;;
		"?") usage 2 "Unknown option: -$OPTARG" ;;
		":") usage 3 "No argument value for option: -$OPTARG" ;;
	esac
done

if [ ! -z "$SRC" ] && [ ! -z "$DST" ]; then

	# check ownership
	SRC_OWNER=`ls -lA "$(dirname $SRC)" | grep ' '"$(basename $SRC)"'$' | awk '{print $3}'`
	DST_OWNER=`ls -lA "$(dirname $DST)" | grep ' '"$(basename $DST)"'$' | awk '{print $3}'`
	if [ ! -z "$SRC_OWNER" ] && [ ! -z "$DST_OWNER" ] &&\
		[ "$SRC_OWNER" == "$DST_OWNER" ] && [ "$SRC_OWNER" == "$(whoami)" ] ||\
		[ "$(whoami)" == "root" ]; then
		sync
	else
		echo "You are not the owner of the source and/or destination folders and you are not currently running the script as root."
		echo "If you wish to modify a CHROOT environment, you will probably need to be root."
		ask "Do you wish to continue as $(whoami)?" "n" && sync
	fi

else
	usage 4 "Missing options"
fi