diff --git a/mod.test.ts b/mod.test.ts
index 09f669f..38b219b 100644
--- a/mod.test.ts
+++ b/mod.test.ts
@@ -192,6 +192,12 @@ Deno.test("should throw when exit code is non-zero", async () => {
   );
 });
 
+Deno.test("should error in the shell when the command can't be found", async () => {
+  const output = await $`nonexistentcommanddaxtest`.noThrow().stderr("piped");
+  assertEquals(output.code, 127);
+  assertEquals(output.stderr, "dax: nonexistentcommanddaxtest: command not found\n");
+});
+
 Deno.test("throws when providing an object that doesn't override toString", async () => {
   {
     const obj1 = {};
@@ -263,6 +269,11 @@ Deno.test("CommandBuilder#json()", async () => {
   assertEquals(output, { test: 5 });
 });
 
+Deno.test("CommandBuilder#json('stderr')", async () => {
+  const output = await $`deno eval "console.error(JSON.stringify({ test: 5 }));"`.json("stderr");
+  assertEquals(output, { test: 5 });
+});
+
 Deno.test("stderrJson", async () => {
   const output = await $`deno eval "console.error(JSON.stringify({ test: 5 }));"`.stderr("piped");
   assertEquals(output.stderrJson, { test: 5 });
@@ -490,11 +501,9 @@ Deno.test("should not allow invalid command names", () => {
 
 Deno.test("should unregister commands", async () => {
   const builder = new CommandBuilder().unregisterCommand("export").noThrow();
-  await assertRejects(
-    async () => await builder.command("export somewhere"),
-    Error,
-    "Command not found: export",
-  );
+  const output = await builder.command("export somewhere").stderr("piped");
+  assertEquals(output.code, 127);
+  assertEquals(output.stderr, "dax: export: command not found\n");
 });
 
 Deno.test("sleep command", async () => {
@@ -1124,6 +1133,16 @@ Deno.test("command .lines()", async () => {
   assertEquals(result, ["1", "2"]);
 });
 
+Deno.test("command .lines('stderr')", async () => {
+  const result = await $`deno eval "console.error(1); console.error(2)"`.lines("stderr");
+  assertEquals(result, ["1", "2"]);
+});
+
+Deno.test("command .lines('combined')", async () => {
+  const result = await $`deno eval "console.log(1); console.error(2)"`.lines("combined");
+  assertEquals(result, ["1", "2"]);
+});
+
 Deno.test("piping in command", async () => {
   await withTempDir(async (tempDir) => {
     const result = await $`echo 1 | cat - > output.txt`.cwd(tempDir).text();
@@ -1438,7 +1457,7 @@ Deno.test("shebang support", async (t) => {
             .text();
         },
         Error,
-        "Command not found: deno run",
+        "Exited with code: 127",
       );
     });
 
diff --git a/src/command.ts b/src/command.ts
index e066b5b..de1c9a2 100644
--- a/src/command.ts
+++ b/src/command.ts
@@ -38,6 +38,7 @@ import { symbols } from "./common.ts";
 import { whichCommand } from "./commands/which.ts";
 
 type BufferStdio = "inherit" | "null" | "streamed" | Buffer;
+type StreamKind = "stdout" | "stderr" | "combined";
 
 class Deferred<T> {
   #create: () => T | Promise<T>;
@@ -492,12 +493,13 @@ export class CommandBuilder implements PromiseLike<CommandResult> {
    * await $`echo 1`.quiet("stderr");
    * ```
    */
-  quiet(kind: "stdout" | "stderr" | "both" = "both"): CommandBuilder {
+  quiet(kind: StreamKind | "both" = "combined"): CommandBuilder {
+    kind = kind === "both" ? "combined" : kind;
     return this.#newWithState((state) => {
-      if (kind === "both" || kind === "stdout") {
+      if (kind === "combined" || kind === "stdout") {
         state.stdout.kind = getQuietKind(state.stdout.kind);
       }
-      if (kind === "both" || kind === "stderr") {
+      if (kind === "combined" || kind === "stderr") {
         state.stderr.kind = getQuietKind(state.stderr.kind);
       }
     });
@@ -543,12 +545,14 @@ export class CommandBuilder implements PromiseLike<CommandResult> {
    * const data = (await $`command`.quiet("stdout")).stdoutBytes;
    * ```
    */
-  async bytes(): Promise<Uint8Array> {
-    return (await this.quiet("stdout")).stdoutBytes;
+  async bytes(kind: StreamKind): Promise<Uint8Array> {
+    const command = kind === "combined" ? this.quiet(kind).captureCombined() : this.quiet(kind);
+    return (await command)[`${kind}Bytes`];
   }
 
   /**
-   * Sets stdout as quiet, spawns the command, and gets stdout as a string without the last newline.
+   * Sets the provided stream (stdout by default) as quiet, spawns the command, and gets the stream as a string without the last newline.
+   * Can be used to get stdout, stderr, or both.
    *
    * Shorthand for:
    *
@@ -556,18 +560,19 @@ export class CommandBuilder implements PromiseLike<CommandResult> {
    * const data = (await $`command`.quiet("stdout")).stdout.replace(/\r?\n$/, "");
    * ```
    */
-  async text(): Promise<string> {
-    return (await this.quiet("stdout")).stdout.replace(/\r?\n$/, "");
+  async text(kind: StreamKind = "stdout"): Promise<string> {
+    const command = kind === "combined" ? this.quiet(kind).captureCombined() : this.quiet(kind);
+    return (await command)[kind].replace(/\r?\n$/, "");
   }
 
   /** Gets the text as an array of lines. */
-  async lines(): Promise<string[]> {
-    const text = await this.text();
+  async lines(kind: StreamKind = "stdout"): Promise<string[]> {
+    const text = await this.text(kind);
     return text.split(/\r?\n/g);
   }
 
   /**
-   * Sets stdout as quiet, spawns the command, and gets stdout as JSON.
+   * Sets stream (stdout by default) as quiet, spawns the command, and gets stream as JSON.
    *
    * Shorthand for:
    *
@@ -575,8 +580,8 @@ export class CommandBuilder implements PromiseLike<CommandResult> {
    * const data = (await $`command`.quiet("stdout")).stdoutJson;
    * ```
    */
-  async json<TResult = any>(): Promise<TResult> {
-    return (await this.quiet("stdout")).stdoutJson;
+  async json<TResult = any>(kind: Exclude<StreamKind, "combined"> = "stdout"): Promise<TResult> {
+    return (await this.quiet(kind))[`${kind}Json`];
   }
 
   /** @internal */
diff --git a/src/shell.ts b/src/shell.ts
index ffa72fc..ff91a26 100644
--- a/src/shell.ts
+++ b/src/shell.ts
@@ -928,6 +928,10 @@ async function executeUnresolvedCommand(
   context: Context,
 ): Promise<ExecuteResult> {
   const resolvedCommand = await resolveCommand(unresolvedCommand, context);
+  if (resolvedCommand === false) {
+    context.stderr.writeLine(`dax: ${unresolvedCommand.name}: command not found`);
+    return { code: 127 };
+  }
   if (resolvedCommand.kind === "shebang") {
     return executeUnresolvedCommand(resolvedCommand.command, [...resolvedCommand.args, ...commandArgs], context);
   }
@@ -1113,7 +1117,7 @@ function pipeCommandPipeReaderToWriterSync(
   }
 }
 
-type ResolvedCommand = ResolvedPathCommand | ResolvedShebangCommand;
+type ResolvedCommand = ResolvedPathCommand | ResolvedShebangCommand | false;
 
 interface ResolvedPathCommand {
   kind: "path";
@@ -1141,7 +1145,7 @@ async function resolveCommand(unresolvedCommand: UnresolvedCommand, context: Con
     // won't have a script with a shebang in it on Windows
     const result = await getExecutableShebangFromPath(commandPath);
     if (result === false) {
-      throw new Error(`Command not found: ${unresolvedCommand.name}`);
+      return false;
     } else if (result != null) {
       const args = await parseShebangArgs(result, context);
       const name = args.shift()!;
@@ -1165,7 +1169,7 @@ async function resolveCommand(unresolvedCommand: UnresolvedCommand, context: Con
 
   const commandPath = await whichFromContext(unresolvedCommand.name, context);
   if (commandPath == null) {
-    throw new Error(`Command not found: ${unresolvedCommand.name}`);
+    return false;
   }
   return {
     kind: "path",