can1357/oh-my-pi · error · MkTempError

with --suffix, template {} must end in X

Error message

with --suffix, template {} must end in X

What it means

MkTempError::MustEndInX is raised by the builtin `mktemp` when --suffix is supplied but the template does not end in X (after accounting for the suffix). With --suffix, GNU mktemp requires the X-run to terminate the template portion so it can correctly splice the generated random characters before the suffix. This prevents ambiguous or corrupted filenames.

Source

Thrown at crates/pi-builtins/src/mktemp.rs:57

static OPT_TMPDIR: &str = "tmpdir";
static OPT_P: &str = "p";
static OPT_T: &str = "t";

static ARG_TEMPLATE: &str = "template";

#[cfg(not(windows))]
const TMPDIR_ENV_VAR: &str = "TMPDIR";
#[cfg(windows)]
const TMPDIR_ENV_VAR: &str = "TMP";

const FALLBACK_TMPDIR: &str = "/tmp";

#[derive(Error, Debug)]
enum MkTempError {
	#[error("could not persist file {}", .0.quote())]
	Persist(PathBuf),

	#[error("with --suffix, template {} must end in X", .0.quote())]
	MustEndInX(String),

	#[error("too few X's in template {}", .0.quote())]
	TooFewXs(String),

	#[error("invalid template, {}, contains directory separator", .0.quote())]
	PrefixContainsDirSeparator(String),

	#[error("invalid suffix {}, contains directory separator", .0.quote())]
	SuffixContainsDirSeparator(String),

	#[error("invalid template, {}; with --tmpdir, it may not be absolute", .0.quote())]
	InvalidTemplate(OsString),

	#[error("too many templates")]
	TooManyTemplates,

	#[error("failed to create {} via template {}: No such file or directory", .0, .1.quote())]

View on GitHub (pinned to 9690622007)

Solutions

1. End the template with X's right before the suffix: `mktemp --suffix=.txt XXXXXX`
2. Move trailing non-X characters out of the template into --suffix
3. Drop --suffix and embed the whole pattern manually if a non-X tail is truly needed (then the X-run must still be at the end)
4. Ensure no whitespace or hidden characters trail the X-run in the template

Example fix

// before
mktemp --suffix=.log fooXXXXbar
// after
mktemp --suffix=.log fooXXXX

function checkSuffixTemplate(template: string, hasSuffix: boolean): void {
  if (hasSuffix && !/X[^X]*$/.test(template) === false) {
    // with --suffix the template portion must END in X
  }
  if (hasSuffix && !template.endsWith('X')) {
    throw new RangeError(`with --suffix, template '${template}' must end in X`);
  }
}

const endsInX = (t: string): boolean => t.endsWith('X');

try {
  await Bun.$`mktemp --suffix=${suffix} ${tmpl}`.quiet();
} catch (e) {
  if (String(e).includes('must end in X')) {
    // move trailing non-X chars into the suffix and retry
    await Bun.$`mktemp --suffix=${tail + suffix} ${tmpl.replace(/[^X]+$/, '')}`.quiet();
  } else throw e;
}

When it happens

Trigger: Calling `mktemp --suffix=.txt fooXXXXbar` where the template part doesn't end in X, or `mktemp --suffix=.log templateXXextra`.

Common situations: Moving from plain `mktemp fooXXXXXX` to suffixed form without realizing the X-run must end at the template/suffix boundary; building templates dynamically where the suffix got merged into the template string.

Related errors

• too few X's in template {}
• invalid template, {}; with --tmpdir, it may not be absolute
• unknown file type: {value}
• invalid size: {value}
• 2

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/017b21cc700b5cb5. Report an issue: GitHub.