simplified install

install.sh

@@ -2,36 +2,39 @@
 
 ## CONSTANTS
 
-readonly DESTINATION=/opt
+readonly MIAOU_BASH_DIR=/opt/miaou-bash
 readonly MAIN_TAR_GZ_URL="https://git.artcode.re/miaou/miaou-bash/archive/main.tar.gz"
 
 ## FUNCTIONS
 
 function bootstrap {
-  if [[ ! -d "$DESTINATION/miaou-bash" ]]; then
-    local temp_dir
-    temp_dir=$(mktemp -d)
-    pushd "$temp_dir" >/dev/null || return 2
-    curl -s -O $MAIN_TAR_GZ_URL
-    tar -xzf main.tar.gz --directory "$DESTINATION"
-    echo "directory: miaou-bash successfully deployed to $DESTINATION"
-    popd >/dev/null || return 3
-  fi
+  cd "$(mktemp -d)" || exit 3
+  curl -s -O $MAIN_TAR_GZ_URL
+  tar -xzf main.tar.gz --directory "$MIAOU_BASH_DIR/.."
 
-  local source_bin="$DESTINATION/miaou-bash/bin/miaou-bash"
+  local source_bin="$MIAOU_BASH_DIR/bin/miaou-bash"
   local dest_bin="/usr/bin/miaou-bash"
   if ! cmp -s "$source_bin" "$dest_bin"; then
     cp -f "$source_bin" "$dest_bin"
-    echo "executable: /usr/bin/miaou-bash freshly created"
   fi
+  echo "miaou-bash deployed to: $MIAOU_BASH_DIR"
 
-  export MIAOU_BASH_DIR="$DESTINATION/miaou-bash"
+}
+
+function assert_supported_distro {
+  grep -E '^ID=debian|^ID_LIKE=debian' /etc/os-release ||
+    grep -E '^ID=arch|^ID_LIKE=arch' /etc/os-release
 }
 
 ## MAIN
 
+set -Eeuo pipefail
+
 [[ "$UID" -ne 0 ]] && echo 'root privilege required' && exit 1
-if [[ -v MIAOU_BASH_DIR && -d "$MIAOU_BASH_DIR" ]]; then
+! assert_supported_distro && echo 'unsupported distro: debian-like OR arch-like expected' && exit 2
+
+export MIAOU_BASH_DIR
+if [[ -d "$MIAOU_BASH_DIR" ]]; then
   miaou-bash "$MIAOU_BASH_DIR/lib/self-upgrade.bash"
 else
   bootstrap