unpack

#!/bin/bash
# depends on GNU TAR
# author jjm2473

TAR=tar
gtar --version >/dev/null 2>&1 && TAR=gtar

usage() {
    echo "$0 ABC.ipk"
    echo "    Extract ABC.ipk to ABC"
}

[[ -z "$1" ]] && {
    usage
    exit 0
}

IPK=$1

[[ -f "$1" ]] || {
    echo "$1 does not existed" >&2
    exit 1
}

DIR=${IPK%%.ipk}

[[ -e "$DIR" ]] && {
    echo "target dir $DIR already exists, please delete it" >&2
    exit 1
}

mkdir -p "$DIR"

cat "$IPK" | $TAR -C "$DIR" -xz

[[ -f "$DIR/control.tar.gz" ]] || {
    echo "extract failed, or it's not a IPK file" >&2
    exit 1
}

(
    cd "$DIR"
    [[ -f data.tar.gz ]] && cat data.tar.gz | $TAR -xz
    mkdir CONTROL || exit 1
    cat control.tar.gz | $TAR -C CONTROL -xz
    rm -f data.tar.gz control.tar.gz debian-binary
)

echo "Successfully unpack $IPK to $DIR"