diff --git a/server-install.sh b/server-install.sh
index edd33c6..4b4d728 100755
--- a/server-install.sh
+++ b/server-install.sh
@@ -50,11 +50,11 @@ fi
 TTY=
 if (: </dev/tty) 2>/dev/null; then TTY=/dev/tty; fi
 
-# ask VAR "question" default: the answer from the terminal, else the
-# environment's LPRA_<VAR>, else the default.
+# ask VAR "question" default [KEY]: the answer from the terminal, else the
+# environment's LPRA_<KEY> (KEY is VAR if not given), else the default.
 ask() {
-  var=$1 q=$2 def=$3
-  eval "env=\${LPRA_$var:-}"
+  var=$1 q=$2 def=$3 key=${4:-$1}
+  eval "env=\${LPRA_$key:-}"
   [ -n "$env" ] && def=$env
   ans=
   if [ -n "$TTY" ]; then
@@ -64,11 +64,11 @@ ask() {
   [ -n "$ans" ] || ans=$def
   eval "$var=\$ans"
 }
-# confirm VAR "question" y|n: true for a yes.
+# confirm KEY "question" y|n: true for a yes (LPRA_<KEY> without a terminal).
+# The answer stays apart from the script's own variables of that name.
 confirm() {
-  ask "$1" "$2 (y/n)" "$3"
-  eval "v=\$$1"
-  case "$v" in [yYдД]*) return 0 ;; *) return 1 ;; esac
+  ask _yn "$2 (y/n)" "$3" "$1"
+  case "$_yn" in [yYдД]*) return 0 ;; *) return 1 ;; esac
 }
 
 # ---------- download ----------