Struct ExitCode

pub struct ExitCode(/* private fields */);

This type represents the status code the current process can return to its parent under normal termination.

ExitCode is intended to be consumed only by the standard library (via Termination::report()). For forwards compatibility with potentially unusual targets, this type currently does not provide Eq, Hash, or access to the raw value. This type does provide PartialEq for comparison, but note that there may potentially be multiple failure codes, some of which will not compare equal to ExitCode::FAILURE. The standard library provides the canonical SUCCESS and FAILURE exit codes as well as From<u8> for ExitCode for constructing other arbitrary exit codes.

Portability

Numeric values used in this type don’t have portable meanings, and different platforms may mask different amounts of them.

For the platform’s canonical successful and unsuccessful codes, see the SUCCESS and FAILURE associated items.

Differences from ExitStatus

ExitCode is intended for terminating the currently running process, via the Termination trait, in contrast to ExitStatus, which represents the termination of a child process. These APIs are separate due to platform compatibility differences and their expected usage; it is not generally possible to exactly reproduce an ExitStatus from a child for the current process after the fact.

Examples

ExitCode can be returned from the main function of a crate, as it implements Termination:

use std::process::ExitCode;

fn main() -> ExitCode {
    if !check_foo() {
        return ExitCode::from(42);
    }

    ExitCode::SUCCESS
}

Implementations

impl ExitCode

pub const SUCCESS: ExitCode

The canonical ExitCode for successful termination on this platform.

Note that a ()-returning main implicitly results in a successful termination, so there’s no need to return this from main unless you’re also returning other possible codes.

pub const FAILURE: ExitCode

The canonical ExitCode for unsuccessful termination on this platform.

If you’re only returning this and SUCCESS from main, consider instead returning Err(_) and Ok(()) respectively, which will return the same codes (but will also eprintln! the error).

pub fn exit_process(self) -> !

🔬This is a nightly-only experimental API. (exitcode_exit_method #97100)

Exit the current process with the given ExitCode.

Note that this has the same caveats as process::exit(), namely that this function terminates the process immediately, so no destructors on the current stack or any other thread’s stack will be run. Also see those docs for some important notes on interop with C code. If a clean shutdown is needed, it is recommended to simply return this ExitCode from the main function, as demonstrated in the type documentation.

Differences from process::exit()

process::exit() accepts any i32 value as the exit code for the process; however, there are platforms that only use a subset of that value (see process::exit platform-specific behavior). ExitCode exists because of this; only ExitCodes that are supported by a majority of our platforms can be created, so those problems don’t exist (as much) with this method.

Examples

#![feature(exitcode_exit_method)]
// there's no way to gracefully recover from an UhOhError, so we just
// print a message and exit
fn handle_unrecoverable_error(err: UhOhError) -> ! {
    eprintln!("UH OH! {err}");
    let code = match err {
        UhOhError::GenericProblem => ExitCode::FAILURE,
        UhOhError::Specific => ExitCode::from(3),
        UhOhError::WithCode { exit_code, .. } => exit_code,
    };
    code.exit_process()
}

Trait Implementations

impl Clone for ExitCode

fn clone(&self) -> ExitCode

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ExitCode

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ExitCode

The default value is ExitCode::SUCCESS

fn default() -> Self

Returns the “default value” for a type.

impl ExitCodeExt for ExitCode

Available on Windows only.

fn from_raw(raw: u32) -> Self

🔬This is a nightly-only experimental API. (windows_process_exit_code_from #111688)

Creates a new ExitCode from the raw underlying u32 return value of a process.

impl From<u8> for ExitCode

fn from(code: u8) -> Self

Constructs an ExitCode from an arbitrary u8 value.

impl PartialEq for ExitCode

fn eq(&self, other: &ExitCode) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Termination for ExitCode

fn report(self) -> ExitCode

Is called to get the representation of the value as status code. This status code is returned to the operating system.

impl Copy for ExitCode

impl StructuralPartialEq for ExitCode