Inform the user that the environment variable UE_ROOT is not set. (#104)

Author: carryaimp

build.sh

@@ -4,4 +4,10 @@
 # MIT License.
 
 set -e
+
+# Inform the user that the environment variable UE_ROOT is not set.
+if [ -z "$UE_ROOT" ]; then
+    echo "Warning: The UE_ROOT environment variable is not set." >&2
+fi
+
 make -f build_linux.mk $1

setup_linux_dev_tools.sh

@@ -5,6 +5,11 @@
 
 set -e
 
+# Inform the user that the environment variable UE_ROOT is not set.
+if [ -z "$UE_ROOT" ]; then
+    echo "Warning: The UE_ROOT environment variable is not set." >&2
+fi
+
 sudo apt-get update
 
 # Install lsb_release to check Ubuntu version