fix: do not use build-arg at runtime

Author: git-developer

Dockerfile.alpine

@@ -2,5 +2,6 @@ FROM alpine
 RUN  apk update && apk add --no-cache linux-tools-usbip
 RUN  if [ ! -e /usr/share/hwdata/usb.ids ]; then mkdir -p /usr/share/hwdata && ln -s /dev/null /usr/share/hwdata/usb.ids; fi
 ARG  SERVICE
-COPY usbip-common.sh "${SERVICE}/init" /opt/usbip-${SERVICE}/
-CMD  [ "/opt/usbip-${SERVICE}/init" ]
+ENV  USBIP_HOME="/opt/usbip-${SERVICE}"
+COPY usbip-common.sh "${SERVICE}/init" "${USBIP_HOME}/"
+CMD  exec "${USBIP_HOME}/init"

Dockerfile.bullseye

@@ -1,5 +1,6 @@
 FROM debian:bullseye-slim
 RUN  apt-get update && apt-get install -y usbip && apt-get clean
 ARG  SERVICE
-COPY usbip-common.sh "${SERVICE}/init" "/opt/usbip-${SERVICE}/"
-CMD  [ "/opt/usbip-${SERVICE}/init" ]
+ENV  USBIP_HOME="/opt/usbip-${SERVICE}"
+COPY usbip-common.sh "${SERVICE}/init" "${USBIP_HOME}/"
+CMD  exec "${USBIP_HOME}/init"

Dockerfile.buster

@@ -1,8 +1,9 @@
 FROM debian:buster-slim
 RUN  apt-get update && apt-get install -y usbip && apt-get clean
 ARG  SERVICE
-COPY usbip-common.sh "${SERVICE}/init" "/opt/usbip-${SERVICE}/"
+ENV  USBIP_HOME="/opt/usbip-${SERVICE}"
+COPY usbip-common.sh "${SERVICE}/init" "${USBIP_HOME}/"
 # bash is preferred over sh as workaround for
 # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=779416
 # affected package is dash:0.5.10.2-5, fixed in 0.5.11
-CMD  [ "bash", "/opt/usbip-${SERVICE}/init" ]
+CMD  exec bash "${USBIP_HOME}/init"

build

@@ -1,7 +1,8 @@
 #!/bin/sh
 set -eu
+distros="${1:-*}"
 dir="$(dirname "${0}")"
-find "${dir}" -maxdepth 1 -name 'Dockerfile.*' -printf '%f\n' \
+find "${dir}" -maxdepth 1 -name "Dockerfile.${distros}" -printf '%f\n' \
 | while read file; do
   distro="${file##Dockerfile.}"
   find  "${dir}" -maxdepth 1 -type d ! -iname ".*" -printf '%f\n' \