feat: add require-read-r rule

README.md

@@ -93,6 +93,7 @@ Each rule mirrors a well-known ShellCheck check.
 | [`no-unquoted-expansions`](./docs/rules/no-unquoted-expansions.md)                 | SC2086/46  | Quote expansions subject to word splitting and globbing | ✅      | error       |
 | [`no-useless-cat`](./docs/rules/no-useless-cat.md)                                 | SC2002     | Don't pipe from a single-file `cat`                     |         | error       |
 | [`no-useless-echo`](./docs/rules/no-useless-echo.md)                               | SC2116     | Disallow `$(echo ...)`                                  |         | error       |
+| [`require-read-r`](./docs/rules/require-read-r.md)                                 | SC2162     | Use `read -r` so backslashes aren't mangled             | ✅      | error       |
 
 ## Configuration comments
 

docs/rules/require-read-r.md

@@ -0,0 +1,51 @@
+# require-read-r
+
+Require `read -r` so backslashes are not mangled.
+
+## Background
+
+By default, `read` treats backslashes in its input as escape characters: it removes them and joins lines that end in a backslash. Input such as `C:\temp` or a line ending in `\` is silently changed. The `-r` option makes `read` keep backslashes as they are, which is almost always what you want.
+
+## Rule Details
+
+This rule warns about `read` commands that don't pass the `-r` option. The option can appear alone (`-r`) or combined with other short options (`-rs`), anywhere before `--`.
+
+This rule is autofixable: it inserts `-r` immediately after `read`.
+
+Examples of **incorrect** code for this rule:
+
+```bash
+# eslint shell/require-read-r: "error"
+
+read line
+
+read -p "Name: " name
+
+while read line; do echo "$line"; done < input.txt
+```
+
+Examples of **correct** code for this rule:
+
+```bash
+# eslint shell/require-read-r: "error"
+
+read -r line
+
+read -r -p "Name: " name
+
+read -rs password
+
+while IFS= read -r line; do echo "$line"; done < input.txt
+```
+
+## Options
+
+This rule has no options.
+
+## When Not to Use It
+
+If you intentionally want `read` to interpret backslash escapes, for example to allow line continuations in input, you can disable this rule for those lines.
+
+## Prior Art
+
+- [SC2162](https://www.shellcheck.net/wiki/SC2162)

src/index.spec.ts

@@ -50,6 +50,7 @@ describe("plugin", () => {
 			"no-unquoted-expansions",
 			"no-useless-cat",
 			"no-useless-echo",
+			"require-read-r",
 		]);
 	});
 

src/index.ts

@@ -15,6 +15,7 @@ import noLsIteration from "./rules/no-ls-iteration.js";
 import noUnquotedExpansions from "./rules/no-unquoted-expansions.js";
 import noUselessCat from "./rules/no-useless-cat.js";
 import noUselessEcho from "./rules/no-useless-echo.js";
+import requireReadR from "./rules/require-read-r.js";
 
 //------------------------------------------------------------------------------
 // Plugin
@@ -27,6 +28,7 @@ const rules = {
 	"no-unquoted-expansions": noUnquotedExpansions,
 	"no-useless-cat": noUselessCat,
 	"no-useless-echo": noUselessEcho,
+	"require-read-r": requireReadR,
 };
 
 const plugin = {
@@ -54,6 +56,7 @@ const plugin = {
 				"shell/no-unquoted-expansions": "error",
 				"shell/no-useless-cat": "error",
 				"shell/no-useless-echo": "error",
+				"shell/require-read-r": "error",
 			},
 		},
 	},

src/rules/require-read-r.spec.ts

@@ -0,0 +1,72 @@
+/**
+ * @fileoverview Tests for the require-read-r rule.
+ * @author Claude Opus 5.5
+ */
+
+//------------------------------------------------------------------------------
+// Imports
+//------------------------------------------------------------------------------
+
+import { RuleTester } from "eslint";
+import { ShellLanguage } from "../languages/shell-language.js";
+import rule from "./require-read-r.js";
+
+//------------------------------------------------------------------------------
+// Tests
+//------------------------------------------------------------------------------
+
+const ruleTester = new RuleTester({
+	plugins: {
+		shell: {
+			meta: { namespace: "shell" },
+			languages: { bash: new ShellLanguage() },
+		},
+		// eslint-disable-next-line @typescript-eslint/no-explicit-any -- plugin shape is validated by ESLint at runtime.
+	} as any,
+	language: "shell/bash",
+});
+
+ruleTester.run("require-read-r", rule as never, {
+	valid: [
+		"read -r line",
+		"read -rs password",
+		"read -r -a parts",
+		'while read -r line; do echo "$line"; done < file',
+		// Not the read builtin
+		"gread line",
+	],
+	invalid: [
+		{
+			code: "read line",
+			output: "read -r line",
+			errors: [
+				{
+					messageId: "missingR",
+					line: 1,
+					column: 1,
+					endColumn: 5,
+				},
+			],
+		},
+		{
+			code: "read -s password",
+			output: "read -r -s password",
+			errors: [{ messageId: "missingR" }],
+		},
+		{
+			code: "read -d -r value",
+			output: "read -r -d -r value",
+			errors: [{ messageId: "missingR" }],
+		},
+		{
+			code: "read -dr value",
+			output: "read -r -dr value",
+			errors: [{ messageId: "missingR" }],
+		},
+		{
+			code: 'while read line; do echo "$line"; done < file',
+			output: 'while read -r line; do echo "$line"; done < file',
+			errors: [{ messageId: "missingR" }],
+		},
+	],
+});

src/rules/require-read-r.ts

@@ -0,0 +1,115 @@
+/**
+ * @fileoverview Rule to require the `-r` flag when using `read`.
+ * Mirrors ShellCheck SC2162.
+ * @author Claude Opus 5.5
+ */
+
+//------------------------------------------------------------------------------
+// Imports
+//------------------------------------------------------------------------------
+
+import { getCommandName, getStaticText } from "./utils.js";
+import type { ShellRuleDefinition } from "../types.js";
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+const optionsWithArguments = new Set(["a", "d", "i", "n", "N", "p", "t", "u"]);
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+const rule: ShellRuleDefinition<{ MessageIds: "missingR" }> = {
+	meta: {
+		type: "problem",
+		languages: ["shell/bash", "shell/posix", "shell/mksh"],
+		docs: {
+			description: "Require `read -r` so backslashes are not mangled",
+			recommended: true,
+			dialects: ["Bash", "POSIX sh", "mksh"],
+			url: "https://github.com/eslint/shell/blob/main/docs/rules/require-read-r.md",
+		},
+		fixable: "code",
+		schema: [],
+		messages: {
+			missingR:
+				"read without -r will mangle backslashes. (ShellCheck SC2162)",
+		},
+	},
+
+	create(context) {
+		return {
+			Command(node) {
+				if (getCommandName(node) !== "read" || !node.name) {
+					return;
+				}
+
+				let hasRawOption = false;
+
+				for (let index = 0; index < node.arguments.length; index++) {
+					const argument = node.arguments[index];
+					if (!argument) {
+						continue;
+					}
+
+					const text = getStaticText(argument);
+					if (text === "--") {
+						break;
+					}
+
+					if (
+						text === null ||
+						!text.startsWith("-") ||
+						text === "-"
+					) {
+						continue;
+					}
+
+					for (
+						let optionIndex = 1;
+						optionIndex < text.length;
+						optionIndex++
+					) {
+						const option = text[optionIndex];
+						if (!option) {
+							break;
+						}
+
+						if (option === "r") {
+							hasRawOption = true;
+							break;
+						}
+
+						if (optionsWithArguments.has(option)) {
+							if (optionIndex === text.length - 1) {
+								index++;
+							}
+
+							break;
+						}
+					}
+
+					if (hasRawOption) {
+						break;
+					}
+				}
+
+				if (hasRawOption) {
+					return;
+				}
+
+				const name = node.name;
+
+				context.report({
+					node: name,
+					messageId: "missingR",
+					fix: fixer => fixer.insertTextAfter(name, " -r"),
+				});
+			},
+		};
+	},
+};
+
+export default rule;

tests/autofix.test.ts

@@ -54,4 +54,12 @@ describe("autofix", () => {
 
 		expect(result.output).toBe('cp "$src" "$dest"\n');
 	});
+
+	it("should add -r to read", () => {
+		const result = fix('read line\necho "$line"\n', {
+			"shell/require-read-r": "error",
+		});
+
+		expect(result.output).toBe('read -r line\necho "$line"\n');
+	});
 });