diff --git a/shell/install.sh b/shell/install.sh
index f848c17325a..6b04fc1e576 100755
--- a/shell/install.sh
+++ b/shell/install.sh
@@ -186,14 +186,20 @@ usage() {
     echo "using '--fresh' or '--dev'"
 }
 
+# Conditionally connect /dev/tty when
+# the environment variable TTY is set to 1
+TTY=${TTY-0}
 R=
 prompt() {
-  # expects to be called as prompt "Do you want to do this? [Y/n]"
+  # expects to be called as prompt "Do you want to do this? [Y/n] "
   printf "$1"
-  read R </dev/tty
+  if [ "$TTY" = 1 ]; then
+    read R </dev/tty
+  else
+    read R
+  fi
 }
 
-
 RESTORE=
 NOBACKUP=
 FRESH=