Fix empty and commented lines within script execution

Resolves #1315
Resolves #1316

Signed-off-by: David Pilar <david@czpilar.net>

Author: czpilar

spring-shell-core/src/main/java/org/springframework/shell/core/FileInputProvider.java

@@ -19,6 +19,7 @@
 import java.io.*;
 
 import org.jspecify.annotations.Nullable;
+import org.springframework.util.StringUtils;
 
 /**
  * An {@link InputProvider} that reads input from a file.
@@ -29,6 +30,7 @@
  * @author Eric Bottard
  * @author Piotr Olaszewski
  * @author Mahmoud Ben Hassine
+ * @author David Pilar
  */
 public class FileInputProvider implements InputProvider, AutoCloseable {
 
@@ -59,9 +61,12 @@ public FileInputProvider(File file) throws FileNotFoundException {
 			sb.append(line.replaceFirst(BACKSLASH_AT_EOL_REGEX, "$1 "));
 		}
 		while (continued);
-		if (line == null || isComment(line)) {
+		if (line == null) {
 			return null;
 		}
+		else if (!StringUtils.hasLength(line) || isComment(line)) {
+			return readInput();
+		}
 		else {
 			return sb.toString();
 		}

spring-shell-core/src/test/java/org/springframework/shell/core/FileInputProviderTests.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2026-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.shell.core;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.CleanupMode;
+import org.junit.jupiter.api.io.TempDir;
+
+import java.io.File;
+import java.nio.file.Files;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+/**
+ * @author David Pilar
+ */
+class FileInputProviderTests {
+
+	@TempDir(cleanup = CleanupMode.ALWAYS)
+	private File tempDir;
+
+	@Test
+	void testReadInput() throws Exception {
+		// given
+		File inputFile = new File(tempDir, "input.txt");
+		String inputContent = """
+				echo Hello World
+				// This is a comment
+				echo Line 1\\
+				Line 2
+
+				echo Line 3""";
+		Files.writeString(inputFile.toPath(), inputContent);
+
+		// when & then
+		try (FileInputProvider inputProvider = new FileInputProvider(inputFile)) {
+			assertEquals("echo Hello World", inputProvider.readInput());
+			assertEquals("echo Line 1 Line 2", inputProvider.readInput());
+			assertEquals("echo Line 3", inputProvider.readInput());
+			assertNull(inputProvider.readInput());
+		}
+	}
+
+}

spring-shell-docs/modules/ROOT/pages/commands/builtin/script.adoc

@@ -10,4 +10,4 @@ This command expects a file absolute path as an option, which points to the scri
 $>script --file /absolute/path/to/your/script.txt
 ----
 
-The script file should contain one command per line, and the commands will be executed in the order they appear in the file. Comments can be added to the script file by starting a line with a `#` character.
+The script file should contain one command per line, and the commands will be executed in the order they appear in the file. Comments can be added to the script file by starting a line with `//` characters.