Assume yes if we have no TTY

Starve the TTY of input to ensure this works, but provide yes to the
current installer to handle the current broken case.

scripts/install-darwin-multi-user.sh

@@ -43,6 +43,12 @@ readonly EXTRACTED_NIX_PATH="$(dirname "$0")"
 
 readonly ROOT_HOME="/var/root"
 
+if [ -t 0 ]; then
+    readonly IS_HEADLESS='no'
+else
+    readonly IS_HEADLESS='yes'
+fi
+
 contactme() {
     echo "We'd love to help if you need it."
     echo ""
@@ -173,6 +179,11 @@ failure() {
 ui_confirm() {
     _textout "$GREEN$GREEN_UL" "$1"
 
+    if [ "$IS_HEADLESS" = "yes" ]; then
+        echo "No TTY, assuming you would say yes :)"
+        return 0
+    fi
+
     local prompt="[y/n] "
     echo -n "$prompt"
     while read -r y; do

tests/install-darwin.sh

@@ -53,7 +53,8 @@ trap finish EXIT
 
 # First setup Nix
 cleanup
-curl https://nixos.org/nix/install | bash
+curl -o install https://nixos.org/nix/install
+yes | bash ./install
 verify
 
 
@@ -82,7 +83,7 @@ verify
 
     cleanup
 
-    yes | ./install
+    echo -n "" | ./install
     verify
 
     cleanup