busybox-static

#!/usr/bin/env bash
set -e

rootfsDir="$1"
shift

busybox="$(which busybox 2>/dev/null || true)"
if [ -z "$busybox" ]; then
	echo >&2 'error: busybox: not found'
	echo >&2 '  install it with your distribution "busybox-static" package'
	exit 1
fi
if ! ldd "$busybox" 2>&1 | grep -q 'not a dynamic executable'; then
	echo >&2 "error: '$busybox' appears to be a dynamic executable"
	echo >&2 '  you should install your distribution "busybox-static" package instead'
	exit 1
fi

mkdir -p "$rootfsDir/bin"
rm -f "$rootfsDir/bin/busybox" # just in case
cp "$busybox" "$rootfsDir/bin/busybox"

(
	cd "$rootfsDir"

	IFS=$'\n'
	modules=( $(bin/busybox --list-modules) )
	unset IFS

	for module in "${modules[@]}"; do
		mkdir -p "$(dirname "$module")"
		ln -sf /bin/busybox "$module"
	done
)