denoland/deno · error

Failed to read from stdin

Error message

Failed to read from stdin

What it means

When linting from stdin, Deno reads all of standard input into a String via read_to_string. Any read failure — most commonly non-UTF-8 bytes in the stream — aborts with this message before linting begins.

Source

Thrown at cli/tools/lint/mod.rs:613

) -> Result<bool, AnyError> {
  let start_dir = &cli_options.start_dir;
  let reporter_lock = Arc::new(Mutex::new(create_reporter(
    workspace_lint_options.reporter_kind,
  )));
  let lint_config = start_dir
    .to_lint_config(FilePatterns::new_with_base(start_dir.dir_path()))?;
  let deno_lint_config =
    resolve_lint_config(compiler_options_resolver, start_dir.dir_url())?;
  let lint_options = LintOptions::resolve(lint_config, &lint_flags)?;
  let configured_rules = lint_rule_provider
    .resolve_lint_rules_err_empty(lint_options.rules, Some(start_dir))?;
  let mut file_path = cli_options.initial_cwd().join(STDIN_FILE_NAME);
  if let Some(ext) = cli_options.ext_flag() {
    file_path.set_extension(ext);
  }
  let mut source_code = String::new();
  if stdin().read_to_string(&mut source_code).is_err() {
    return Err(anyhow!("Failed to read from stdin"));
  }

  let linter = CliLinter::new(CliLinterOptions {
    fix: false,
    configured_rules,
    deno_lint_config,
    maybe_plugin_runner: None,
  });

  let r = linter.lint_file(&file_path, deno_ast::strip_bom(source_code), None);

  let success =
    handle_lint_result(&file_path.to_string_lossy(), r, reporter_lock.clone());
  reporter_lock.lock().close(1);
  Ok(success)
}

fn handle_lint_result(

View on GitHub (pinned to 89f33cbef2)

Solutions

1. Confirm the input is UTF-8 text (file src.ts or iconv probe)
2. Convert before piping: iconv -f UTF-16 -t UTF-8 src.ts | deno lint -
3. Pass file paths to deno lint instead of concatenating many files through stdin
4. Note: BOMs are handled (strip_bom); only encoding/IO breakage triggers this

Example fix

# before (src.ts is UTF-16)
cat src.ts | deno lint -
# after
iconv -f UTF-16 -t UTF-8 src.ts | deno lint -

# bail on non-UTF-8 before invoking deno
if ! iconv -f UTF-8 -t UTF-8 src.ts >/dev/null 2>&1; then
  echo "src.ts is not valid UTF-8" >&2
  exit 2
fi
cat src.ts | deno lint -

When it happens

Trigger: Piping binary or non-UTF-8-encoded content into `deno lint -` (e.g. cat icon.png | deno lint -), a broken/closed pipe mid-read, or a source file in UTF-16/latin-1 encoding.

Common situations: Windows-created files saved as UTF-16; accidentally concatenating a binary file into the lint stream; tooling that closes stdin early.

Related errors

• Lint watch on standard input is not supported.
• ${prefix}Linter plugin name must only contain lowercase lett
• ${prefix}Linter plugin name must start and end with a lowerc
• ${prefix}Linter plugin name must not have consequtive hyphen
• ${prefix}Linter plugin rules must be an object

AI-assisted analysis of denoland/deno@89f33cbef2 (2026-08-16). Data as JSON: /api/errors/5fc9dc75cbeb19f6. Report an issue: GitHub.