Fix stdin piping to nested bash -c commands

src/Bash.ts

@@ -199,6 +199,11 @@ export interface ExecOptions {
    * Default: false
    */
   rawScript?: boolean;
+  /**
+   * Standard input to pass to the script.
+   * This will be available to commands via stdin (e.g., for `bash -c 'cat'`).
+   */
+  stdin?: string;
 }
 
 export class Bash {
@@ -504,6 +509,8 @@ export class Bash {
       options: { ...this.state.options },
       // Share hashTable reference - it should persist across exec calls
       hashTable: this.state.hashTable,
+      // Pass stdin through to commands (for bash -c with piped input)
+      groupStdin: options?.stdin,
     };
 
     // Normalize indented multi-line scripts (unless rawScript is true)

src/commands/bash/bash.test.ts

@@ -200,4 +200,42 @@ cat /tmp/test.txt`,
       expect(result.exitCode).toBe(0);
     });
   });
+
+  describe("stdin piping to nested bash -c", () => {
+    it("should handle stdin when piping to bash -c with command substitution", async () => {
+      const env = new Bash();
+      // This is the key test case: piping stdin to a nested bash -c command
+      // The stdin should be available to commands inside the bash -c script
+      const result = await env.exec(
+        'echo "hello world" | bash -c \'DATA=$(cat); echo "$DATA"\'',
+      );
+      expect(result.stdout).toBe("hello world\n");
+      expect(result.exitCode).toBe(0);
+    });
+
+    it("should handle stdin with multiple commands in bash -c", async () => {
+      const env = new Bash();
+      const result = await env.exec(
+        'echo "test data" | bash -c \'read LINE; echo "Got: $LINE"\'',
+      );
+      expect(result.stdout).toBe("Got: test data\n");
+      expect(result.exitCode).toBe(0);
+    });
+
+    it("should handle stdin piping to sh -c", async () => {
+      const env = new Bash();
+      const result = await env.exec("echo \"from stdin\" | sh -c 'cat'");
+      expect(result.stdout).toBe("from stdin\n");
+      expect(result.exitCode).toBe(0);
+    });
+
+    it("should handle complex piping with bash -c", async () => {
+      const env = new Bash();
+      const result = await env.exec(
+        "echo -e \"line1\\nline2\\nline3\" | bash -c 'grep line2'",
+      );
+      expect(result.stdout).toBe("line2\n");
+      expect(result.exitCode).toBe(0);
+    });
+  });
 });

src/commands/bash/bash.ts

@@ -151,9 +151,11 @@ async function executeScript(
   // Execute the script as-is, preserving newlines for proper parsing
   // The parser needs to see the original structure to correctly handle
   // multi-line constructs like (( ... )) vs ( ( ... ) )
+  // Pass stdin through to the nested script
   const result = await ctx.exec(scriptToRun, {
     env: positionalEnv,
     cwd: ctx.cwd,
+    stdin: ctx.stdin,
   });
   return result;
 }

src/types.ts

@@ -33,6 +33,11 @@ export interface CommandExecOptions {
    * Always pass `ctx.cwd` from the calling command's context.
    */
   cwd: string;
+  /**
+   * Standard input to pass to the subcommand.
+   * Optional - if not provided, stdin will be empty.
+   */
+  stdin?: string;
 }
 
 /**