Add yornp (y-or-n-p)

I'm not sure if this flow is really what I want to happen .. is it too easy?

1 files changed, 17 insertions, 0 deletions

@@ -103,6 +103,13 @@ main() {
         # to use the default configuration.
         log error "Can't find configuration \`$CONFIG'."
         exit 2
+    else
+        print >&2 "I'm not sure this is a \`vienna' site directory."
+        if yornp "Initialize? (y/N)"; then
+            initialize
+        else
+            yornp "Continue building? (y/N)" || exit 2
+        fi
     fi
     # Further argument processing --- pre-build
     preprocess "$@" || shift
@@ -298,6 +305,16 @@ print() {
     printf '%s\n' "$*"
 }
 
+yornp() { # yornp PROMPT
+    printf >&2 '%s \n' "$@"
+    read -r yn
+    case "$yn" in
+        [Nn]*) return 1 ;;
+        [Yy]*) return 0 ;;
+        *) return 2 ;;
+    esac
+}
+
 ### File processing
 
 ## Building block functions