refactor

image/substitution.sh

@@ -0,0 +1,32 @@
+#!/bin/sh
+
+current_file=""
+root="/kitchen/overlay"
+
+while IFS= read -r line; do
+    case "$line" in
+        \#\ /*)
+            current_file="${line#\# }"
+            ;;
+        \#\:*)
+            continue
+            ;;
+        *=*)
+            if [ -z "$current_file" ]; then
+                echo "warning: value without file: $line" >&2
+                continue
+            fi
+            key="${line%%=*}"
+            value="${line#*=}"
+            key_esc=$(printf '%s' "$key" | sed 's/[]\/$*.^[]/\\&/g')
+            value_esc=$(printf '%s' "$value" | sed 's/[\/&]/\\&/g')
+            sed -i "s/_${key_esc}_/${value_esc}/g" "$root$current_file"
+            ;;
+        "")
+            continue
+            ;;
+        *)
+            echo "unknown line: $line" >&2
+            ;;
+    esac
+done