std/
process.rs

1//! A module for working with processes.
2//!
3//! This module is mostly concerned with spawning and interacting with child
4//! processes, but it also provides [`abort`] and [`exit`] for terminating the
5//! current process.
6//!
7//! # Spawning a process
8//!
9//! The [`Command`] struct is used to configure and spawn processes:
10//!
11//! ```no_run
12//! use std::process::Command;
13//!
14//! let output = Command::new("echo")
15//!     .arg("Hello world")
16//!     .output()
17//!     .expect("Failed to execute command");
18//!
19//! assert_eq!(b"Hello world\n", output.stdout.as_slice());
20//! ```
21//!
22//! Several methods on [`Command`], such as [`spawn`] or [`output`], can be used
23//! to spawn a process. In particular, [`output`] spawns the child process and
24//! waits until the process terminates, while [`spawn`] will return a [`Child`]
25//! that represents the spawned child process.
26//!
27//! # Handling I/O
28//!
29//! The [`stdout`], [`stdin`], and [`stderr`] of a child process can be
30//! configured by passing an [`Stdio`] to the corresponding method on
31//! [`Command`]. Once spawned, they can be accessed from the [`Child`]. For
32//! example, piping output from one command into another command can be done
33//! like so:
34//!
35//! ```no_run
36//! use std::process::{Command, Stdio};
37//!
38//! // stdout must be configured with `Stdio::piped` in order to use
39//! // `echo_child.stdout`
40//! let echo_child = Command::new("echo")
41//!     .arg("Oh no, a tpyo!")
42//!     .stdout(Stdio::piped())
43//!     .spawn()
44//!     .expect("Failed to start echo process");
45//!
46//! // Note that `echo_child` is moved here, but we won't be needing
47//! // `echo_child` anymore
48//! let echo_out = echo_child.stdout.expect("Failed to open echo stdout");
49//!
50//! let mut sed_child = Command::new("sed")
51//!     .arg("s/tpyo/typo/")
52//!     .stdin(Stdio::from(echo_out))
53//!     .stdout(Stdio::piped())
54//!     .spawn()
55//!     .expect("Failed to start sed process");
56//!
57//! let output = sed_child.wait_with_output().expect("Failed to wait on sed");
58//! assert_eq!(b"Oh no, a typo!\n", output.stdout.as_slice());
59//! ```
60//!
61//! Note that [`ChildStderr`] and [`ChildStdout`] implement [`Read`] and
62//! [`ChildStdin`] implements [`Write`]:
63//!
64//! ```no_run
65//! use std::process::{Command, Stdio};
66//! use std::io::Write;
67//!
68//! let mut child = Command::new("/bin/cat")
69//!     .stdin(Stdio::piped())
70//!     .stdout(Stdio::piped())
71//!     .spawn()
72//!     .expect("failed to execute child");
73//!
74//! // If the child process fills its stdout buffer, it may end up
75//! // waiting until the parent reads the stdout, and not be able to
76//! // read stdin in the meantime, causing a deadlock.
77//! // Writing from another thread ensures that stdout is being read
78//! // at the same time, avoiding the problem.
79//! let mut stdin = child.stdin.take().expect("failed to get stdin");
80//! std::thread::spawn(move || {
81//!     stdin.write_all(b"test").expect("failed to write to stdin");
82//! });
83//!
84//! let output = child
85//!     .wait_with_output()
86//!     .expect("failed to wait on child");
87//!
88//! assert_eq!(b"test", output.stdout.as_slice());
89//! ```
90//!
91//! # Windows argument splitting
92//!
93//! On Unix systems arguments are passed to a new process as an array of strings,
94//! but on Windows arguments are passed as a single commandline string and it is
95//! up to the child process to parse it into an array. Therefore the parent and
96//! child processes must agree on how the commandline string is encoded.
97//!
98//! Most programs use the standard C run-time `argv`, which in practice results
99//! in consistent argument handling. However, some programs have their own way of
100//! parsing the commandline string. In these cases using [`arg`] or [`args`] may
101//! result in the child process seeing a different array of arguments than the
102//! parent process intended.
103//!
104//! Two ways of mitigating this are:
105//!
106//! * Validate untrusted input so that only a safe subset is allowed.
107//! * Use [`raw_arg`] to build a custom commandline. This bypasses the escaping
108//!   rules used by [`arg`] so should be used with due caution.
109//!
110//! `cmd.exe` and `.bat` files use non-standard argument parsing and are especially
111//! vulnerable to malicious input as they may be used to run arbitrary shell
112//! commands. Untrusted arguments should be restricted as much as possible.
113//! For examples on handling this see [`raw_arg`].
114//!
115//! ### Batch file special handling
116//!
117//! On Windows, `Command` uses the Windows API function [`CreateProcessW`] to
118//! spawn new processes. An undocumented feature of this function is that
119//! when given a `.bat` file as the application to run, it will automatically
120//! convert that into running `cmd.exe /c` with the batch file as the next argument.
121//!
122//! For historical reasons Rust currently preserves this behavior when using
123//! [`Command::new`], and escapes the arguments according to `cmd.exe` rules.
124//! Due to the complexity of `cmd.exe` argument handling, it might not be
125//! possible to safely escape some special characters, and using them will result
126//! in an error being returned at process spawn. The set of unescapeable
127//! special characters might change between releases.
128//!
129//! Also note that running batch scripts in this way may be removed in the
130//! future and so should not be relied upon.
131//!
132//! [`spawn`]: Command::spawn
133//! [`output`]: Command::output
134//!
135//! [`stdout`]: Command::stdout
136//! [`stdin`]: Command::stdin
137//! [`stderr`]: Command::stderr
138//!
139//! [`Write`]: io::Write
140//! [`Read`]: io::Read
141//!
142//! [`arg`]: Command::arg
143//! [`args`]: Command::args
144//! [`raw_arg`]: crate::os::windows::process::CommandExt::raw_arg
145//!
146//! [`CreateProcessW`]: https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessw
147
148#![stable(feature = "process", since = "1.0.0")]
149#![deny(unsafe_op_in_unsafe_fn)]
150
151#[cfg(all(
152    test,
153    not(any(
154        target_os = "emscripten",
155        target_os = "wasi",
156        target_env = "sgx",
157        target_os = "xous"
158    ))
159))]
160mod tests;
161
162use crate::convert::Infallible;
163use crate::ffi::OsStr;
164use crate::io::prelude::*;
165use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
166use crate::num::NonZero;
167use crate::path::Path;
168use crate::sys::pipe::{AnonPipe, read2};
169use crate::sys::process as imp;
170#[stable(feature = "command_access", since = "1.57.0")]
171pub use crate::sys_common::process::CommandEnvs;
172use crate::sys_common::{AsInner, AsInnerMut, FromInner, IntoInner};
173use crate::{fmt, fs, str};
174
175/// Representation of a running or exited child process.
176///
177/// This structure is used to represent and manage child processes. A child
178/// process is created via the [`Command`] struct, which configures the
179/// spawning process and can itself be constructed using a builder-style
180/// interface.
181///
182/// There is no implementation of [`Drop`] for child processes,
183/// so if you do not ensure the `Child` has exited then it will continue to
184/// run, even after the `Child` handle to the child process has gone out of
185/// scope.
186///
187/// Calling [`wait`] (or other functions that wrap around it) will make
188/// the parent process wait until the child has actually exited before
189/// continuing.
190///
191/// # Warning
192///
193/// On some systems, calling [`wait`] or similar is necessary for the OS to
194/// release resources. A process that terminated but has not been waited on is
195/// still around as a "zombie". Leaving too many zombies around may exhaust
196/// global resources (for example process IDs).
197///
198/// The standard library does *not* automatically wait on child processes (not
199/// even if the `Child` is dropped), it is up to the application developer to do
200/// so. As a consequence, dropping `Child` handles without waiting on them first
201/// is not recommended in long-running applications.
202///
203/// # Examples
204///
205/// ```should_panic
206/// use std::process::Command;
207///
208/// let mut child = Command::new("/bin/cat")
209///     .arg("file.txt")
210///     .spawn()
211///     .expect("failed to execute child");
212///
213/// let ecode = child.wait().expect("failed to wait on child");
214///
215/// assert!(ecode.success());
216/// ```
217///
218/// [`wait`]: Child::wait
219#[stable(feature = "process", since = "1.0.0")]
220pub struct Child {
221    pub(crate) handle: imp::Process,
222
223    /// The handle for writing to the child's standard input (stdin), if it
224    /// has been captured. You might find it helpful to do
225    ///
226    /// ```ignore (incomplete)
227    /// let stdin = child.stdin.take().expect("handle present");
228    /// ```
229    ///
230    /// to avoid partially moving the `child` and thus blocking yourself from calling
231    /// functions on `child` while using `stdin`.
232    #[stable(feature = "process", since = "1.0.0")]
233    pub stdin: Option<ChildStdin>,
234
235    /// The handle for reading from the child's standard output (stdout), if it
236    /// has been captured. You might find it helpful to do
237    ///
238    /// ```ignore (incomplete)
239    /// let stdout = child.stdout.take().expect("handle present");
240    /// ```
241    ///
242    /// to avoid partially moving the `child` and thus blocking yourself from calling
243    /// functions on `child` while using `stdout`.
244    #[stable(feature = "process", since = "1.0.0")]
245    pub stdout: Option<ChildStdout>,
246
247    /// The handle for reading from the child's standard error (stderr), if it
248    /// has been captured. You might find it helpful to do
249    ///
250    /// ```ignore (incomplete)
251    /// let stderr = child.stderr.take().expect("handle present");
252    /// ```
253    ///
254    /// to avoid partially moving the `child` and thus blocking yourself from calling
255    /// functions on `child` while using `stderr`.
256    #[stable(feature = "process", since = "1.0.0")]
257    pub stderr: Option<ChildStderr>,
258}
259
260/// Allows extension traits within `std`.
261#[unstable(feature = "sealed", issue = "none")]
262impl crate::sealed::Sealed for Child {}
263
264impl AsInner<imp::Process> for Child {
265    #[inline]
266    fn as_inner(&self) -> &imp::Process {
267        &self.handle
268    }
269}
270
271impl FromInner<(imp::Process, imp::StdioPipes)> for Child {
272    fn from_inner((handle, io): (imp::Process, imp::StdioPipes)) -> Child {
273        Child {
274            handle,
275            stdin: io.stdin.map(ChildStdin::from_inner),
276            stdout: io.stdout.map(ChildStdout::from_inner),
277            stderr: io.stderr.map(ChildStderr::from_inner),
278        }
279    }
280}
281
282impl IntoInner<imp::Process> for Child {
283    fn into_inner(self) -> imp::Process {
284        self.handle
285    }
286}
287
288#[stable(feature = "std_debug", since = "1.16.0")]
289impl fmt::Debug for Child {
290    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
291        f.debug_struct("Child")
292            .field("stdin", &self.stdin)
293            .field("stdout", &self.stdout)
294            .field("stderr", &self.stderr)
295            .finish_non_exhaustive()
296    }
297}
298
299/// A handle to a child process's standard input (stdin).
300///
301/// This struct is used in the [`stdin`] field on [`Child`].
302///
303/// When an instance of `ChildStdin` is [dropped], the `ChildStdin`'s underlying
304/// file handle will be closed. If the child process was blocked on input prior
305/// to being dropped, it will become unblocked after dropping.
306///
307/// [`stdin`]: Child::stdin
308/// [dropped]: Drop
309#[stable(feature = "process", since = "1.0.0")]
310pub struct ChildStdin {
311    inner: AnonPipe,
312}
313
314// In addition to the `impl`s here, `ChildStdin` also has `impl`s for
315// `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
316// `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
317// `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
318// `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
319
320#[stable(feature = "process", since = "1.0.0")]
321impl Write for ChildStdin {
322    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
323        (&*self).write(buf)
324    }
325
326    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
327        (&*self).write_vectored(bufs)
328    }
329
330    fn is_write_vectored(&self) -> bool {
331        io::Write::is_write_vectored(&&*self)
332    }
333
334    #[inline]
335    fn flush(&mut self) -> io::Result<()> {
336        (&*self).flush()
337    }
338}
339
340#[stable(feature = "write_mt", since = "1.48.0")]
341impl Write for &ChildStdin {
342    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
343        self.inner.write(buf)
344    }
345
346    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
347        self.inner.write_vectored(bufs)
348    }
349
350    fn is_write_vectored(&self) -> bool {
351        self.inner.is_write_vectored()
352    }
353
354    #[inline]
355    fn flush(&mut self) -> io::Result<()> {
356        Ok(())
357    }
358}
359
360impl AsInner<AnonPipe> for ChildStdin {
361    #[inline]
362    fn as_inner(&self) -> &AnonPipe {
363        &self.inner
364    }
365}
366
367impl IntoInner<AnonPipe> for ChildStdin {
368    fn into_inner(self) -> AnonPipe {
369        self.inner
370    }
371}
372
373impl FromInner<AnonPipe> for ChildStdin {
374    fn from_inner(pipe: AnonPipe) -> ChildStdin {
375        ChildStdin { inner: pipe }
376    }
377}
378
379#[stable(feature = "std_debug", since = "1.16.0")]
380impl fmt::Debug for ChildStdin {
381    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
382        f.debug_struct("ChildStdin").finish_non_exhaustive()
383    }
384}
385
386/// A handle to a child process's standard output (stdout).
387///
388/// This struct is used in the [`stdout`] field on [`Child`].
389///
390/// When an instance of `ChildStdout` is [dropped], the `ChildStdout`'s
391/// underlying file handle will be closed.
392///
393/// [`stdout`]: Child::stdout
394/// [dropped]: Drop
395#[stable(feature = "process", since = "1.0.0")]
396pub struct ChildStdout {
397    inner: AnonPipe,
398}
399
400// In addition to the `impl`s here, `ChildStdout` also has `impl`s for
401// `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
402// `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
403// `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
404// `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
405
406#[stable(feature = "process", since = "1.0.0")]
407impl Read for ChildStdout {
408    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
409        self.inner.read(buf)
410    }
411
412    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
413        self.inner.read_buf(buf)
414    }
415
416    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
417        self.inner.read_vectored(bufs)
418    }
419
420    #[inline]
421    fn is_read_vectored(&self) -> bool {
422        self.inner.is_read_vectored()
423    }
424
425    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
426        self.inner.read_to_end(buf)
427    }
428}
429
430impl AsInner<AnonPipe> for ChildStdout {
431    #[inline]
432    fn as_inner(&self) -> &AnonPipe {
433        &self.inner
434    }
435}
436
437impl IntoInner<AnonPipe> for ChildStdout {
438    fn into_inner(self) -> AnonPipe {
439        self.inner
440    }
441}
442
443impl FromInner<AnonPipe> for ChildStdout {
444    fn from_inner(pipe: AnonPipe) -> ChildStdout {
445        ChildStdout { inner: pipe }
446    }
447}
448
449#[stable(feature = "std_debug", since = "1.16.0")]
450impl fmt::Debug for ChildStdout {
451    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
452        f.debug_struct("ChildStdout").finish_non_exhaustive()
453    }
454}
455
456/// A handle to a child process's stderr.
457///
458/// This struct is used in the [`stderr`] field on [`Child`].
459///
460/// When an instance of `ChildStderr` is [dropped], the `ChildStderr`'s
461/// underlying file handle will be closed.
462///
463/// [`stderr`]: Child::stderr
464/// [dropped]: Drop
465#[stable(feature = "process", since = "1.0.0")]
466pub struct ChildStderr {
467    inner: AnonPipe,
468}
469
470// In addition to the `impl`s here, `ChildStderr` also has `impl`s for
471// `AsFd`/`From<OwnedFd>`/`Into<OwnedFd>` and
472// `AsRawFd`/`IntoRawFd`/`FromRawFd`, on Unix and WASI, and
473// `AsHandle`/`From<OwnedHandle>`/`Into<OwnedHandle>` and
474// `AsRawHandle`/`IntoRawHandle`/`FromRawHandle` on Windows.
475
476#[stable(feature = "process", since = "1.0.0")]
477impl Read for ChildStderr {
478    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
479        self.inner.read(buf)
480    }
481
482    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
483        self.inner.read_buf(buf)
484    }
485
486    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
487        self.inner.read_vectored(bufs)
488    }
489
490    #[inline]
491    fn is_read_vectored(&self) -> bool {
492        self.inner.is_read_vectored()
493    }
494
495    fn read_to_end(&mut self, buf: &mut Vec<u8>) -> io::Result<usize> {
496        self.inner.read_to_end(buf)
497    }
498}
499
500impl AsInner<AnonPipe> for ChildStderr {
501    #[inline]
502    fn as_inner(&self) -> &AnonPipe {
503        &self.inner
504    }
505}
506
507impl IntoInner<AnonPipe> for ChildStderr {
508    fn into_inner(self) -> AnonPipe {
509        self.inner
510    }
511}
512
513impl FromInner<AnonPipe> for ChildStderr {
514    fn from_inner(pipe: AnonPipe) -> ChildStderr {
515        ChildStderr { inner: pipe }
516    }
517}
518
519#[stable(feature = "std_debug", since = "1.16.0")]
520impl fmt::Debug for ChildStderr {
521    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
522        f.debug_struct("ChildStderr").finish_non_exhaustive()
523    }
524}
525
526/// A process builder, providing fine-grained control
527/// over how a new process should be spawned.
528///
529/// A default configuration can be
530/// generated using `Command::new(program)`, where `program` gives a path to the
531/// program to be executed. Additional builder methods allow the configuration
532/// to be changed (for example, by adding arguments) prior to spawning:
533///
534/// ```
535/// use std::process::Command;
536///
537/// let output = if cfg!(target_os = "windows") {
538///     Command::new("cmd")
539///         .args(["/C", "echo hello"])
540///         .output()
541///         .expect("failed to execute process")
542/// } else {
543///     Command::new("sh")
544///         .arg("-c")
545///         .arg("echo hello")
546///         .output()
547///         .expect("failed to execute process")
548/// };
549///
550/// let hello = output.stdout;
551/// ```
552///
553/// `Command` can be reused to spawn multiple processes. The builder methods
554/// change the command without needing to immediately spawn the process.
555///
556/// ```no_run
557/// use std::process::Command;
558///
559/// let mut echo_hello = Command::new("sh");
560/// echo_hello.arg("-c").arg("echo hello");
561/// let hello_1 = echo_hello.output().expect("failed to execute process");
562/// let hello_2 = echo_hello.output().expect("failed to execute process");
563/// ```
564///
565/// Similarly, you can call builder methods after spawning a process and then
566/// spawn a new process with the modified settings.
567///
568/// ```no_run
569/// use std::process::Command;
570///
571/// let mut list_dir = Command::new("ls");
572///
573/// // Execute `ls` in the current directory of the program.
574/// list_dir.status().expect("process failed to execute");
575///
576/// println!();
577///
578/// // Change `ls` to execute in the root directory.
579/// list_dir.current_dir("/");
580///
581/// // And then execute `ls` again but in the root directory.
582/// list_dir.status().expect("process failed to execute");
583/// ```
584#[stable(feature = "process", since = "1.0.0")]
585#[cfg_attr(not(test), rustc_diagnostic_item = "Command")]
586pub struct Command {
587    inner: imp::Command,
588}
589
590/// Allows extension traits within `std`.
591#[unstable(feature = "sealed", issue = "none")]
592impl crate::sealed::Sealed for Command {}
593
594impl Command {
595    /// Constructs a new `Command` for launching the program at
596    /// path `program`, with the following default configuration:
597    ///
598    /// * No arguments to the program
599    /// * Inherit the current process's environment
600    /// * Inherit the current process's working directory
601    /// * Inherit stdin/stdout/stderr for [`spawn`] or [`status`], but create pipes for [`output`]
602    ///
603    /// [`spawn`]: Self::spawn
604    /// [`status`]: Self::status
605    /// [`output`]: Self::output
606    ///
607    /// Builder methods are provided to change these defaults and
608    /// otherwise configure the process.
609    ///
610    /// If `program` is not an absolute path, the `PATH` will be searched in
611    /// an OS-defined way.
612    ///
613    /// The search path to be used may be controlled by setting the
614    /// `PATH` environment variable on the Command,
615    /// but this has some implementation limitations on Windows
616    /// (see issue #37519).
617    ///
618    /// # Platform-specific behavior
619    ///
620    /// Note on Windows: For executable files with the .exe extension,
621    /// it can be omitted when specifying the program for this Command.
622    /// However, if the file has a different extension,
623    /// a filename including the extension needs to be provided,
624    /// otherwise the file won't be found.
625    ///
626    /// # Examples
627    ///
628    /// ```no_run
629    /// use std::process::Command;
630    ///
631    /// Command::new("sh")
632    ///     .spawn()
633    ///     .expect("sh command failed to start");
634    /// ```
635    ///
636    /// # Caveats
637    ///
638    /// [`Command::new`] is only intended to accept the path of the program. If you pass a program
639    /// path along with arguments like `Command::new("ls -l").spawn()`, it will try to search for
640    /// `ls -l` literally. The arguments need to be passed separately, such as via [`arg`] or
641    /// [`args`].
642    ///
643    /// ```no_run
644    /// use std::process::Command;
645    ///
646    /// Command::new("ls")
647    ///     .arg("-l") // arg passed separately
648    ///     .spawn()
649    ///     .expect("ls command failed to start");
650    /// ```
651    ///
652    /// [`arg`]: Self::arg
653    /// [`args`]: Self::args
654    #[stable(feature = "process", since = "1.0.0")]
655    pub fn new<S: AsRef<OsStr>>(program: S) -> Command {
656        Command { inner: imp::Command::new(program.as_ref()) }
657    }
658
659    /// Adds an argument to pass to the program.
660    ///
661    /// Only one argument can be passed per use. So instead of:
662    ///
663    /// ```no_run
664    /// # std::process::Command::new("sh")
665    /// .arg("-C /path/to/repo")
666    /// # ;
667    /// ```
668    ///
669    /// usage would be:
670    ///
671    /// ```no_run
672    /// # std::process::Command::new("sh")
673    /// .arg("-C")
674    /// .arg("/path/to/repo")
675    /// # ;
676    /// ```
677    ///
678    /// To pass multiple arguments see [`args`].
679    ///
680    /// [`args`]: Command::args
681    ///
682    /// Note that the argument is not passed through a shell, but given
683    /// literally to the program. This means that shell syntax like quotes,
684    /// escaped characters, word splitting, glob patterns, variable substitution,
685    /// etc. have no effect.
686    ///
687    /// <div class="warning">
688    ///
689    /// On Windows, use caution with untrusted inputs. Most applications use the
690    /// standard convention for decoding arguments passed to them. These are safe to
691    /// use with `arg`. However, some applications such as `cmd.exe` and `.bat` files
692    /// use a non-standard way of decoding arguments. They are therefore vulnerable
693    /// to malicious input.
694    ///
695    /// In the case of `cmd.exe` this is especially important because a malicious
696    /// argument can potentially run arbitrary shell commands.
697    ///
698    /// See [Windows argument splitting][windows-args] for more details
699    /// or [`raw_arg`] for manually implementing non-standard argument encoding.
700    ///
701    /// [`raw_arg`]: crate::os::windows::process::CommandExt::raw_arg
702    /// [windows-args]: crate::process#windows-argument-splitting
703    ///
704    /// </div>
705    ///
706    /// # Examples
707    ///
708    /// ```no_run
709    /// use std::process::Command;
710    ///
711    /// Command::new("ls")
712    ///     .arg("-l")
713    ///     .arg("-a")
714    ///     .spawn()
715    ///     .expect("ls command failed to start");
716    /// ```
717    #[stable(feature = "process", since = "1.0.0")]
718    pub fn arg<S: AsRef<OsStr>>(&mut self, arg: S) -> &mut Command {
719        self.inner.arg(arg.as_ref());
720        self
721    }
722
723    /// Adds multiple arguments to pass to the program.
724    ///
725    /// To pass a single argument see [`arg`].
726    ///
727    /// [`arg`]: Command::arg
728    ///
729    /// Note that the arguments are not passed through a shell, but given
730    /// literally to the program. This means that shell syntax like quotes,
731    /// escaped characters, word splitting, glob patterns, variable substitution, etc.
732    /// have no effect.
733    ///
734    /// <div class="warning">
735    ///
736    /// On Windows, use caution with untrusted inputs. Most applications use the
737    /// standard convention for decoding arguments passed to them. These are safe to
738    /// use with `arg`. However, some applications such as `cmd.exe` and `.bat` files
739    /// use a non-standard way of decoding arguments. They are therefore vulnerable
740    /// to malicious input.
741    ///
742    /// In the case of `cmd.exe` this is especially important because a malicious
743    /// argument can potentially run arbitrary shell commands.
744    ///
745    /// See [Windows argument splitting][windows-args] for more details
746    /// or [`raw_arg`] for manually implementing non-standard argument encoding.
747    ///
748    /// [`raw_arg`]: crate::os::windows::process::CommandExt::raw_arg
749    /// [windows-args]: crate::process#windows-argument-splitting
750    ///
751    /// </div>
752    ///
753    /// # Examples
754    ///
755    /// ```no_run
756    /// use std::process::Command;
757    ///
758    /// Command::new("ls")
759    ///     .args(["-l", "-a"])
760    ///     .spawn()
761    ///     .expect("ls command failed to start");
762    /// ```
763    #[stable(feature = "process", since = "1.0.0")]
764    pub fn args<I, S>(&mut self, args: I) -> &mut Command
765    where
766        I: IntoIterator<Item = S>,
767        S: AsRef<OsStr>,
768    {
769        for arg in args {
770            self.arg(arg.as_ref());
771        }
772        self
773    }
774
775    /// Inserts or updates an explicit environment variable mapping.
776    ///
777    /// This method allows you to add an environment variable mapping to the spawned process or
778    /// overwrite a previously set value. You can use [`Command::envs`] to set multiple environment
779    /// variables simultaneously.
780    ///
781    /// Child processes will inherit environment variables from their parent process by default.
782    /// Environment variables explicitly set using [`Command::env`] take precedence over inherited
783    /// variables. You can disable environment variable inheritance entirely using
784    /// [`Command::env_clear`] or for a single key using [`Command::env_remove`].
785    ///
786    /// Note that environment variable names are case-insensitive (but
787    /// case-preserving) on Windows and case-sensitive on all other platforms.
788    ///
789    /// # Examples
790    ///
791    /// ```no_run
792    /// use std::process::Command;
793    ///
794    /// Command::new("ls")
795    ///     .env("PATH", "/bin")
796    ///     .spawn()
797    ///     .expect("ls command failed to start");
798    /// ```
799    #[stable(feature = "process", since = "1.0.0")]
800    pub fn env<K, V>(&mut self, key: K, val: V) -> &mut Command
801    where
802        K: AsRef<OsStr>,
803        V: AsRef<OsStr>,
804    {
805        self.inner.env_mut().set(key.as_ref(), val.as_ref());
806        self
807    }
808
809    /// Inserts or updates multiple explicit environment variable mappings.
810    ///
811    /// This method allows you to add multiple environment variable mappings to the spawned process
812    /// or overwrite previously set values. You can use [`Command::env`] to set a single environment
813    /// variable.
814    ///
815    /// Child processes will inherit environment variables from their parent process by default.
816    /// Environment variables explicitly set using [`Command::envs`] take precedence over inherited
817    /// variables. You can disable environment variable inheritance entirely using
818    /// [`Command::env_clear`] or for a single key using [`Command::env_remove`].
819    ///
820    /// Note that environment variable names are case-insensitive (but case-preserving) on Windows
821    /// and case-sensitive on all other platforms.
822    ///
823    /// # Examples
824    ///
825    /// ```no_run
826    /// use std::process::{Command, Stdio};
827    /// use std::env;
828    /// use std::collections::HashMap;
829    ///
830    /// let filtered_env : HashMap<String, String> =
831    ///     env::vars().filter(|&(ref k, _)|
832    ///         k == "TERM" || k == "TZ" || k == "LANG" || k == "PATH"
833    ///     ).collect();
834    ///
835    /// Command::new("printenv")
836    ///     .stdin(Stdio::null())
837    ///     .stdout(Stdio::inherit())
838    ///     .env_clear()
839    ///     .envs(&filtered_env)
840    ///     .spawn()
841    ///     .expect("printenv failed to start");
842    /// ```
843    #[stable(feature = "command_envs", since = "1.19.0")]
844    pub fn envs<I, K, V>(&mut self, vars: I) -> &mut Command
845    where
846        I: IntoIterator<Item = (K, V)>,
847        K: AsRef<OsStr>,
848        V: AsRef<OsStr>,
849    {
850        for (ref key, ref val) in vars {
851            self.inner.env_mut().set(key.as_ref(), val.as_ref());
852        }
853        self
854    }
855
856    /// Removes an explicitly set environment variable and prevents inheriting it from a parent
857    /// process.
858    ///
859    /// This method will remove the explicit value of an environment variable set via
860    /// [`Command::env`] or [`Command::envs`]. In addition, it will prevent the spawned child
861    /// process from inheriting that environment variable from its parent process.
862    ///
863    /// After calling [`Command::env_remove`], the value associated with its key from
864    /// [`Command::get_envs`] will be [`None`].
865    ///
866    /// To clear all explicitly set environment variables and disable all environment variable
867    /// inheritance, you can use [`Command::env_clear`].
868    ///
869    /// # Examples
870    ///
871    /// Prevent any inherited `GIT_DIR` variable from changing the target of the `git` command,
872    /// while allowing all other variables, like `GIT_AUTHOR_NAME`.
873    ///
874    /// ```no_run
875    /// use std::process::Command;
876    ///
877    /// Command::new("git")
878    ///     .arg("commit")
879    ///     .env_remove("GIT_DIR")
880    ///     .spawn()?;
881    /// # std::io::Result::Ok(())
882    /// ```
883    #[stable(feature = "process", since = "1.0.0")]
884    pub fn env_remove<K: AsRef<OsStr>>(&mut self, key: K) -> &mut Command {
885        self.inner.env_mut().remove(key.as_ref());
886        self
887    }
888
889    /// Clears all explicitly set environment variables and prevents inheriting any parent process
890    /// environment variables.
891    ///
892    /// This method will remove all explicitly added environment variables set via [`Command::env`]
893    /// or [`Command::envs`]. In addition, it will prevent the spawned child process from inheriting
894    /// any environment variable from its parent process.
895    ///
896    /// After calling [`Command::env_clear`], the iterator from [`Command::get_envs`] will be
897    /// empty.
898    ///
899    /// You can use [`Command::env_remove`] to clear a single mapping.
900    ///
901    /// # Examples
902    ///
903    /// The behavior of `sort` is affected by `LANG` and `LC_*` environment variables.
904    /// Clearing the environment makes `sort`'s behavior independent of the parent processes' language.
905    ///
906    /// ```no_run
907    /// use std::process::Command;
908    ///
909    /// Command::new("sort")
910    ///     .arg("file.txt")
911    ///     .env_clear()
912    ///     .spawn()?;
913    /// # std::io::Result::Ok(())
914    /// ```
915    #[stable(feature = "process", since = "1.0.0")]
916    pub fn env_clear(&mut self) -> &mut Command {
917        self.inner.env_mut().clear();
918        self
919    }
920
921    /// Sets the working directory for the child process.
922    ///
923    /// # Platform-specific behavior
924    ///
925    /// If the program path is relative (e.g., `"./script.sh"`), it's ambiguous
926    /// whether it should be interpreted relative to the parent's working
927    /// directory or relative to `current_dir`. The behavior in this case is
928    /// platform specific and unstable, and it's recommended to use
929    /// [`canonicalize`] to get an absolute program path instead.
930    ///
931    /// # Examples
932    ///
933    /// ```no_run
934    /// use std::process::Command;
935    ///
936    /// Command::new("ls")
937    ///     .current_dir("/bin")
938    ///     .spawn()
939    ///     .expect("ls command failed to start");
940    /// ```
941    ///
942    /// [`canonicalize`]: crate::fs::canonicalize
943    #[stable(feature = "process", since = "1.0.0")]
944    pub fn current_dir<P: AsRef<Path>>(&mut self, dir: P) -> &mut Command {
945        self.inner.cwd(dir.as_ref().as_ref());
946        self
947    }
948
949    /// Configuration for the child process's standard input (stdin) handle.
950    ///
951    /// Defaults to [`inherit`] when used with [`spawn`] or [`status`], and
952    /// defaults to [`piped`] when used with [`output`].
953    ///
954    /// [`inherit`]: Stdio::inherit
955    /// [`piped`]: Stdio::piped
956    /// [`spawn`]: Self::spawn
957    /// [`status`]: Self::status
958    /// [`output`]: Self::output
959    ///
960    /// # Examples
961    ///
962    /// ```no_run
963    /// use std::process::{Command, Stdio};
964    ///
965    /// Command::new("ls")
966    ///     .stdin(Stdio::null())
967    ///     .spawn()
968    ///     .expect("ls command failed to start");
969    /// ```
970    #[stable(feature = "process", since = "1.0.0")]
971    pub fn stdin<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
972        self.inner.stdin(cfg.into().0);
973        self
974    }
975
976    /// Configuration for the child process's standard output (stdout) handle.
977    ///
978    /// Defaults to [`inherit`] when used with [`spawn`] or [`status`], and
979    /// defaults to [`piped`] when used with [`output`].
980    ///
981    /// [`inherit`]: Stdio::inherit
982    /// [`piped`]: Stdio::piped
983    /// [`spawn`]: Self::spawn
984    /// [`status`]: Self::status
985    /// [`output`]: Self::output
986    ///
987    /// # Examples
988    ///
989    /// ```no_run
990    /// use std::process::{Command, Stdio};
991    ///
992    /// Command::new("ls")
993    ///     .stdout(Stdio::null())
994    ///     .spawn()
995    ///     .expect("ls command failed to start");
996    /// ```
997    #[stable(feature = "process", since = "1.0.0")]
998    pub fn stdout<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
999        self.inner.stdout(cfg.into().0);
1000        self
1001    }
1002
1003    /// Configuration for the child process's standard error (stderr) handle.
1004    ///
1005    /// Defaults to [`inherit`] when used with [`spawn`] or [`status`], and
1006    /// defaults to [`piped`] when used with [`output`].
1007    ///
1008    /// [`inherit`]: Stdio::inherit
1009    /// [`piped`]: Stdio::piped
1010    /// [`spawn`]: Self::spawn
1011    /// [`status`]: Self::status
1012    /// [`output`]: Self::output
1013    ///
1014    /// # Examples
1015    ///
1016    /// ```no_run
1017    /// use std::process::{Command, Stdio};
1018    ///
1019    /// Command::new("ls")
1020    ///     .stderr(Stdio::null())
1021    ///     .spawn()
1022    ///     .expect("ls command failed to start");
1023    /// ```
1024    #[stable(feature = "process", since = "1.0.0")]
1025    pub fn stderr<T: Into<Stdio>>(&mut self, cfg: T) -> &mut Command {
1026        self.inner.stderr(cfg.into().0);
1027        self
1028    }
1029
1030    /// Executes the command as a child process, returning a handle to it.
1031    ///
1032    /// By default, stdin, stdout and stderr are inherited from the parent.
1033    ///
1034    /// # Examples
1035    ///
1036    /// ```no_run
1037    /// use std::process::Command;
1038    ///
1039    /// Command::new("ls")
1040    ///     .spawn()
1041    ///     .expect("ls command failed to start");
1042    /// ```
1043    #[stable(feature = "process", since = "1.0.0")]
1044    pub fn spawn(&mut self) -> io::Result<Child> {
1045        self.inner.spawn(imp::Stdio::Inherit, true).map(Child::from_inner)
1046    }
1047
1048    /// Executes the command as a child process, waiting for it to finish and
1049    /// collecting all of its output.
1050    ///
1051    /// By default, stdout and stderr are captured (and used to provide the
1052    /// resulting output). Stdin is not inherited from the parent and any
1053    /// attempt by the child process to read from the stdin stream will result
1054    /// in the stream immediately closing.
1055    ///
1056    /// # Examples
1057    ///
1058    /// ```should_panic
1059    /// use std::process::Command;
1060    /// use std::io::{self, Write};
1061    /// let output = Command::new("/bin/cat")
1062    ///     .arg("file.txt")
1063    ///     .output()?;
1064    ///
1065    /// println!("status: {}", output.status);
1066    /// io::stdout().write_all(&output.stdout)?;
1067    /// io::stderr().write_all(&output.stderr)?;
1068    ///
1069    /// assert!(output.status.success());
1070    /// # io::Result::Ok(())
1071    /// ```
1072    #[stable(feature = "process", since = "1.0.0")]
1073    pub fn output(&mut self) -> io::Result<Output> {
1074        let (status, stdout, stderr) = self.inner.output()?;
1075        Ok(Output { status: ExitStatus(status), stdout, stderr })
1076    }
1077
1078    /// Executes a command as a child process, waiting for it to finish and
1079    /// collecting its status.
1080    ///
1081    /// By default, stdin, stdout and stderr are inherited from the parent.
1082    ///
1083    /// # Examples
1084    ///
1085    /// ```should_panic
1086    /// use std::process::Command;
1087    ///
1088    /// let status = Command::new("/bin/cat")
1089    ///     .arg("file.txt")
1090    ///     .status()
1091    ///     .expect("failed to execute process");
1092    ///
1093    /// println!("process finished with: {status}");
1094    ///
1095    /// assert!(status.success());
1096    /// ```
1097    #[stable(feature = "process", since = "1.0.0")]
1098    pub fn status(&mut self) -> io::Result<ExitStatus> {
1099        self.inner
1100            .spawn(imp::Stdio::Inherit, true)
1101            .map(Child::from_inner)
1102            .and_then(|mut p| p.wait())
1103    }
1104
1105    /// Returns the path to the program that was given to [`Command::new`].
1106    ///
1107    /// # Examples
1108    ///
1109    /// ```
1110    /// use std::process::Command;
1111    ///
1112    /// let cmd = Command::new("echo");
1113    /// assert_eq!(cmd.get_program(), "echo");
1114    /// ```
1115    #[must_use]
1116    #[stable(feature = "command_access", since = "1.57.0")]
1117    pub fn get_program(&self) -> &OsStr {
1118        self.inner.get_program()
1119    }
1120
1121    /// Returns an iterator of the arguments that will be passed to the program.
1122    ///
1123    /// This does not include the path to the program as the first argument;
1124    /// it only includes the arguments specified with [`Command::arg`] and
1125    /// [`Command::args`].
1126    ///
1127    /// # Examples
1128    ///
1129    /// ```
1130    /// use std::ffi::OsStr;
1131    /// use std::process::Command;
1132    ///
1133    /// let mut cmd = Command::new("echo");
1134    /// cmd.arg("first").arg("second");
1135    /// let args: Vec<&OsStr> = cmd.get_args().collect();
1136    /// assert_eq!(args, &["first", "second"]);
1137    /// ```
1138    #[stable(feature = "command_access", since = "1.57.0")]
1139    pub fn get_args(&self) -> CommandArgs<'_> {
1140        CommandArgs { inner: self.inner.get_args() }
1141    }
1142
1143    /// Returns an iterator of the environment variables explicitly set for the child process.
1144    ///
1145    /// Environment variables explicitly set using [`Command::env`], [`Command::envs`], and
1146    /// [`Command::env_remove`] can be retrieved with this method.
1147    ///
1148    /// Note that this output does not include environment variables inherited from the parent
1149    /// process.
1150    ///
1151    /// Each element is a tuple key/value pair `(&OsStr, Option<&OsStr>)`. A [`None`] value
1152    /// indicates its key was explicitly removed via [`Command::env_remove`]. The associated key for
1153    /// the [`None`] value will no longer inherit from its parent process.
1154    ///
1155    /// An empty iterator can indicate that no explicit mappings were added or that
1156    /// [`Command::env_clear`] was called. After calling [`Command::env_clear`], the child process
1157    /// will not inherit any environment variables from its parent process.
1158    ///
1159    /// # Examples
1160    ///
1161    /// ```
1162    /// use std::ffi::OsStr;
1163    /// use std::process::Command;
1164    ///
1165    /// let mut cmd = Command::new("ls");
1166    /// cmd.env("TERM", "dumb").env_remove("TZ");
1167    /// let envs: Vec<(&OsStr, Option<&OsStr>)> = cmd.get_envs().collect();
1168    /// assert_eq!(envs, &[
1169    ///     (OsStr::new("TERM"), Some(OsStr::new("dumb"))),
1170    ///     (OsStr::new("TZ"), None)
1171    /// ]);
1172    /// ```
1173    #[stable(feature = "command_access", since = "1.57.0")]
1174    pub fn get_envs(&self) -> CommandEnvs<'_> {
1175        self.inner.get_envs()
1176    }
1177
1178    /// Returns the working directory for the child process.
1179    ///
1180    /// This returns [`None`] if the working directory will not be changed.
1181    ///
1182    /// # Examples
1183    ///
1184    /// ```
1185    /// use std::path::Path;
1186    /// use std::process::Command;
1187    ///
1188    /// let mut cmd = Command::new("ls");
1189    /// assert_eq!(cmd.get_current_dir(), None);
1190    /// cmd.current_dir("/bin");
1191    /// assert_eq!(cmd.get_current_dir(), Some(Path::new("/bin")));
1192    /// ```
1193    #[must_use]
1194    #[stable(feature = "command_access", since = "1.57.0")]
1195    pub fn get_current_dir(&self) -> Option<&Path> {
1196        self.inner.get_current_dir()
1197    }
1198}
1199
1200#[stable(feature = "rust1", since = "1.0.0")]
1201impl fmt::Debug for Command {
1202    /// Format the program and arguments of a Command for display. Any
1203    /// non-utf8 data is lossily converted using the utf8 replacement
1204    /// character.
1205    ///
1206    /// The default format approximates a shell invocation of the program along with its
1207    /// arguments. It does not include most of the other command properties. The output is not guaranteed to work
1208    /// (e.g. due to lack of shell-escaping or differences in path resolution).
1209    /// On some platforms you can use [the alternate syntax] to show more fields.
1210    ///
1211    /// Note that the debug implementation is platform-specific.
1212    ///
1213    /// [the alternate syntax]: fmt#sign0
1214    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1215        self.inner.fmt(f)
1216    }
1217}
1218
1219impl AsInner<imp::Command> for Command {
1220    #[inline]
1221    fn as_inner(&self) -> &imp::Command {
1222        &self.inner
1223    }
1224}
1225
1226impl AsInnerMut<imp::Command> for Command {
1227    #[inline]
1228    fn as_inner_mut(&mut self) -> &mut imp::Command {
1229        &mut self.inner
1230    }
1231}
1232
1233/// An iterator over the command arguments.
1234///
1235/// This struct is created by [`Command::get_args`]. See its documentation for
1236/// more.
1237#[must_use = "iterators are lazy and do nothing unless consumed"]
1238#[stable(feature = "command_access", since = "1.57.0")]
1239#[derive(Debug)]
1240pub struct CommandArgs<'a> {
1241    inner: imp::CommandArgs<'a>,
1242}
1243
1244#[stable(feature = "command_access", since = "1.57.0")]
1245impl<'a> Iterator for CommandArgs<'a> {
1246    type Item = &'a OsStr;
1247    fn next(&mut self) -> Option<&'a OsStr> {
1248        self.inner.next()
1249    }
1250    fn size_hint(&self) -> (usize, Option<usize>) {
1251        self.inner.size_hint()
1252    }
1253}
1254
1255#[stable(feature = "command_access", since = "1.57.0")]
1256impl<'a> ExactSizeIterator for CommandArgs<'a> {
1257    fn len(&self) -> usize {
1258        self.inner.len()
1259    }
1260    fn is_empty(&self) -> bool {
1261        self.inner.is_empty()
1262    }
1263}
1264
1265/// The output of a finished process.
1266///
1267/// This is returned in a Result by either the [`output`] method of a
1268/// [`Command`], or the [`wait_with_output`] method of a [`Child`]
1269/// process.
1270///
1271/// [`output`]: Command::output
1272/// [`wait_with_output`]: Child::wait_with_output
1273#[derive(PartialEq, Eq, Clone)]
1274#[stable(feature = "process", since = "1.0.0")]
1275pub struct Output {
1276    /// The status (exit code) of the process.
1277    #[stable(feature = "process", since = "1.0.0")]
1278    pub status: ExitStatus,
1279    /// The data that the process wrote to stdout.
1280    #[stable(feature = "process", since = "1.0.0")]
1281    pub stdout: Vec<u8>,
1282    /// The data that the process wrote to stderr.
1283    #[stable(feature = "process", since = "1.0.0")]
1284    pub stderr: Vec<u8>,
1285}
1286
1287// If either stderr or stdout are valid utf8 strings it prints the valid
1288// strings, otherwise it prints the byte sequence instead
1289#[stable(feature = "process_output_debug", since = "1.7.0")]
1290impl fmt::Debug for Output {
1291    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
1292        let stdout_utf8 = str::from_utf8(&self.stdout);
1293        let stdout_debug: &dyn fmt::Debug = match stdout_utf8 {
1294            Ok(ref s) => s,
1295            Err(_) => &self.stdout,
1296        };
1297
1298        let stderr_utf8 = str::from_utf8(&self.stderr);
1299        let stderr_debug: &dyn fmt::Debug = match stderr_utf8 {
1300            Ok(ref s) => s,
1301            Err(_) => &self.stderr,
1302        };
1303
1304        fmt.debug_struct("Output")
1305            .field("status", &self.status)
1306            .field("stdout", stdout_debug)
1307            .field("stderr", stderr_debug)
1308            .finish()
1309    }
1310}
1311
1312/// Describes what to do with a standard I/O stream for a child process when
1313/// passed to the [`stdin`], [`stdout`], and [`stderr`] methods of [`Command`].
1314///
1315/// [`stdin`]: Command::stdin
1316/// [`stdout`]: Command::stdout
1317/// [`stderr`]: Command::stderr
1318#[stable(feature = "process", since = "1.0.0")]
1319pub struct Stdio(imp::Stdio);
1320
1321impl Stdio {
1322    /// A new pipe should be arranged to connect the parent and child processes.
1323    ///
1324    /// # Examples
1325    ///
1326    /// With stdout:
1327    ///
1328    /// ```no_run
1329    /// use std::process::{Command, Stdio};
1330    ///
1331    /// let output = Command::new("echo")
1332    ///     .arg("Hello, world!")
1333    ///     .stdout(Stdio::piped())
1334    ///     .output()
1335    ///     .expect("Failed to execute command");
1336    ///
1337    /// assert_eq!(String::from_utf8_lossy(&output.stdout), "Hello, world!\n");
1338    /// // Nothing echoed to console
1339    /// ```
1340    ///
1341    /// With stdin:
1342    ///
1343    /// ```no_run
1344    /// use std::io::Write;
1345    /// use std::process::{Command, Stdio};
1346    ///
1347    /// let mut child = Command::new("rev")
1348    ///     .stdin(Stdio::piped())
1349    ///     .stdout(Stdio::piped())
1350    ///     .spawn()
1351    ///     .expect("Failed to spawn child process");
1352    ///
1353    /// let mut stdin = child.stdin.take().expect("Failed to open stdin");
1354    /// std::thread::spawn(move || {
1355    ///     stdin.write_all("Hello, world!".as_bytes()).expect("Failed to write to stdin");
1356    /// });
1357    ///
1358    /// let output = child.wait_with_output().expect("Failed to read stdout");
1359    /// assert_eq!(String::from_utf8_lossy(&output.stdout), "!dlrow ,olleH");
1360    /// ```
1361    ///
1362    /// Writing more than a pipe buffer's worth of input to stdin without also reading
1363    /// stdout and stderr at the same time may cause a deadlock.
1364    /// This is an issue when running any program that doesn't guarantee that it reads
1365    /// its entire stdin before writing more than a pipe buffer's worth of output.
1366    /// The size of a pipe buffer varies on different targets.
1367    ///
1368    #[must_use]
1369    #[stable(feature = "process", since = "1.0.0")]
1370    pub fn piped() -> Stdio {
1371        Stdio(imp::Stdio::MakePipe)
1372    }
1373
1374    /// The child inherits from the corresponding parent descriptor.
1375    ///
1376    /// # Examples
1377    ///
1378    /// With stdout:
1379    ///
1380    /// ```no_run
1381    /// use std::process::{Command, Stdio};
1382    ///
1383    /// let output = Command::new("echo")
1384    ///     .arg("Hello, world!")
1385    ///     .stdout(Stdio::inherit())
1386    ///     .output()
1387    ///     .expect("Failed to execute command");
1388    ///
1389    /// assert_eq!(String::from_utf8_lossy(&output.stdout), "");
1390    /// // "Hello, world!" echoed to console
1391    /// ```
1392    ///
1393    /// With stdin:
1394    ///
1395    /// ```no_run
1396    /// use std::process::{Command, Stdio};
1397    /// use std::io::{self, Write};
1398    ///
1399    /// let output = Command::new("rev")
1400    ///     .stdin(Stdio::inherit())
1401    ///     .stdout(Stdio::piped())
1402    ///     .output()?;
1403    ///
1404    /// print!("You piped in the reverse of: ");
1405    /// io::stdout().write_all(&output.stdout)?;
1406    /// # io::Result::Ok(())
1407    /// ```
1408    #[must_use]
1409    #[stable(feature = "process", since = "1.0.0")]
1410    pub fn inherit() -> Stdio {
1411        Stdio(imp::Stdio::Inherit)
1412    }
1413
1414    /// This stream will be ignored. This is the equivalent of attaching the
1415    /// stream to `/dev/null`.
1416    ///
1417    /// # Examples
1418    ///
1419    /// With stdout:
1420    ///
1421    /// ```no_run
1422    /// use std::process::{Command, Stdio};
1423    ///
1424    /// let output = Command::new("echo")
1425    ///     .arg("Hello, world!")
1426    ///     .stdout(Stdio::null())
1427    ///     .output()
1428    ///     .expect("Failed to execute command");
1429    ///
1430    /// assert_eq!(String::from_utf8_lossy(&output.stdout), "");
1431    /// // Nothing echoed to console
1432    /// ```
1433    ///
1434    /// With stdin:
1435    ///
1436    /// ```no_run
1437    /// use std::process::{Command, Stdio};
1438    ///
1439    /// let output = Command::new("rev")
1440    ///     .stdin(Stdio::null())
1441    ///     .stdout(Stdio::piped())
1442    ///     .output()
1443    ///     .expect("Failed to execute command");
1444    ///
1445    /// assert_eq!(String::from_utf8_lossy(&output.stdout), "");
1446    /// // Ignores any piped-in input
1447    /// ```
1448    #[must_use]
1449    #[stable(feature = "process", since = "1.0.0")]
1450    pub fn null() -> Stdio {
1451        Stdio(imp::Stdio::Null)
1452    }
1453
1454    /// Returns `true` if this requires [`Command`] to create a new pipe.
1455    ///
1456    /// # Example
1457    ///
1458    /// ```
1459    /// #![feature(stdio_makes_pipe)]
1460    /// use std::process::Stdio;
1461    ///
1462    /// let io = Stdio::piped();
1463    /// assert_eq!(io.makes_pipe(), true);
1464    /// ```
1465    #[unstable(feature = "stdio_makes_pipe", issue = "98288")]
1466    pub fn makes_pipe(&self) -> bool {
1467        matches!(self.0, imp::Stdio::MakePipe)
1468    }
1469}
1470
1471impl FromInner<imp::Stdio> for Stdio {
1472    fn from_inner(inner: imp::Stdio) -> Stdio {
1473        Stdio(inner)
1474    }
1475}
1476
1477#[stable(feature = "std_debug", since = "1.16.0")]
1478impl fmt::Debug for Stdio {
1479    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1480        f.debug_struct("Stdio").finish_non_exhaustive()
1481    }
1482}
1483
1484#[stable(feature = "stdio_from", since = "1.20.0")]
1485impl From<ChildStdin> for Stdio {
1486    /// Converts a [`ChildStdin`] into a [`Stdio`].
1487    ///
1488    /// # Examples
1489    ///
1490    /// `ChildStdin` will be converted to `Stdio` using `Stdio::from` under the hood.
1491    ///
1492    /// ```rust,no_run
1493    /// use std::process::{Command, Stdio};
1494    ///
1495    /// let reverse = Command::new("rev")
1496    ///     .stdin(Stdio::piped())
1497    ///     .spawn()
1498    ///     .expect("failed reverse command");
1499    ///
1500    /// let _echo = Command::new("echo")
1501    ///     .arg("Hello, world!")
1502    ///     .stdout(reverse.stdin.unwrap()) // Converted into a Stdio here
1503    ///     .output()
1504    ///     .expect("failed echo command");
1505    ///
1506    /// // "!dlrow ,olleH" echoed to console
1507    /// ```
1508    fn from(child: ChildStdin) -> Stdio {
1509        Stdio::from_inner(child.into_inner().into())
1510    }
1511}
1512
1513#[stable(feature = "stdio_from", since = "1.20.0")]
1514impl From<ChildStdout> for Stdio {
1515    /// Converts a [`ChildStdout`] into a [`Stdio`].
1516    ///
1517    /// # Examples
1518    ///
1519    /// `ChildStdout` will be converted to `Stdio` using `Stdio::from` under the hood.
1520    ///
1521    /// ```rust,no_run
1522    /// use std::process::{Command, Stdio};
1523    ///
1524    /// let hello = Command::new("echo")
1525    ///     .arg("Hello, world!")
1526    ///     .stdout(Stdio::piped())
1527    ///     .spawn()
1528    ///     .expect("failed echo command");
1529    ///
1530    /// let reverse = Command::new("rev")
1531    ///     .stdin(hello.stdout.unwrap())  // Converted into a Stdio here
1532    ///     .output()
1533    ///     .expect("failed reverse command");
1534    ///
1535    /// assert_eq!(reverse.stdout, b"!dlrow ,olleH\n");
1536    /// ```
1537    fn from(child: ChildStdout) -> Stdio {
1538        Stdio::from_inner(child.into_inner().into())
1539    }
1540}
1541
1542#[stable(feature = "stdio_from", since = "1.20.0")]
1543impl From<ChildStderr> for Stdio {
1544    /// Converts a [`ChildStderr`] into a [`Stdio`].
1545    ///
1546    /// # Examples
1547    ///
1548    /// ```rust,no_run
1549    /// use std::process::{Command, Stdio};
1550    ///
1551    /// let reverse = Command::new("rev")
1552    ///     .arg("non_existing_file.txt")
1553    ///     .stderr(Stdio::piped())
1554    ///     .spawn()
1555    ///     .expect("failed reverse command");
1556    ///
1557    /// let cat = Command::new("cat")
1558    ///     .arg("-")
1559    ///     .stdin(reverse.stderr.unwrap()) // Converted into a Stdio here
1560    ///     .output()
1561    ///     .expect("failed echo command");
1562    ///
1563    /// assert_eq!(
1564    ///     String::from_utf8_lossy(&cat.stdout),
1565    ///     "rev: cannot open non_existing_file.txt: No such file or directory\n"
1566    /// );
1567    /// ```
1568    fn from(child: ChildStderr) -> Stdio {
1569        Stdio::from_inner(child.into_inner().into())
1570    }
1571}
1572
1573#[stable(feature = "stdio_from", since = "1.20.0")]
1574impl From<fs::File> for Stdio {
1575    /// Converts a [`File`](fs::File) into a [`Stdio`].
1576    ///
1577    /// # Examples
1578    ///
1579    /// `File` will be converted to `Stdio` using `Stdio::from` under the hood.
1580    ///
1581    /// ```rust,no_run
1582    /// use std::fs::File;
1583    /// use std::process::Command;
1584    ///
1585    /// // With the `foo.txt` file containing "Hello, world!"
1586    /// let file = File::open("foo.txt")?;
1587    ///
1588    /// let reverse = Command::new("rev")
1589    ///     .stdin(file)  // Implicit File conversion into a Stdio
1590    ///     .output()?;
1591    ///
1592    /// assert_eq!(reverse.stdout, b"!dlrow ,olleH");
1593    /// # std::io::Result::Ok(())
1594    /// ```
1595    fn from(file: fs::File) -> Stdio {
1596        Stdio::from_inner(file.into_inner().into())
1597    }
1598}
1599
1600#[stable(feature = "stdio_from_stdio", since = "1.74.0")]
1601impl From<io::Stdout> for Stdio {
1602    /// Redirect command stdout/stderr to our stdout
1603    ///
1604    /// # Examples
1605    ///
1606    /// ```rust
1607    /// #![feature(exit_status_error)]
1608    /// use std::io;
1609    /// use std::process::Command;
1610    ///
1611    /// # fn test() -> Result<(), Box<dyn std::error::Error>> {
1612    /// let output = Command::new("whoami")
1613    // "whoami" is a command which exists on both Unix and Windows,
1614    // and which succeeds, producing some stdout output but no stderr.
1615    ///     .stdout(io::stdout())
1616    ///     .output()?;
1617    /// output.status.exit_ok()?;
1618    /// assert!(output.stdout.is_empty());
1619    /// # Ok(())
1620    /// # }
1621    /// #
1622    /// # if cfg!(unix) {
1623    /// #     test().unwrap();
1624    /// # }
1625    /// ```
1626    fn from(inherit: io::Stdout) -> Stdio {
1627        Stdio::from_inner(inherit.into())
1628    }
1629}
1630
1631#[stable(feature = "stdio_from_stdio", since = "1.74.0")]
1632impl From<io::Stderr> for Stdio {
1633    /// Redirect command stdout/stderr to our stderr
1634    ///
1635    /// # Examples
1636    ///
1637    /// ```rust
1638    /// #![feature(exit_status_error)]
1639    /// use std::io;
1640    /// use std::process::Command;
1641    ///
1642    /// # fn test() -> Result<(), Box<dyn std::error::Error>> {
1643    /// let output = Command::new("whoami")
1644    ///     .stdout(io::stderr())
1645    ///     .output()?;
1646    /// output.status.exit_ok()?;
1647    /// assert!(output.stdout.is_empty());
1648    /// # Ok(())
1649    /// # }
1650    /// #
1651    /// # if cfg!(unix) {
1652    /// #     test().unwrap();
1653    /// # }
1654    /// ```
1655    fn from(inherit: io::Stderr) -> Stdio {
1656        Stdio::from_inner(inherit.into())
1657    }
1658}
1659
1660/// Describes the result of a process after it has terminated.
1661///
1662/// This `struct` is used to represent the exit status or other termination of a child process.
1663/// Child processes are created via the [`Command`] struct and their exit
1664/// status is exposed through the [`status`] method, or the [`wait`] method
1665/// of a [`Child`] process.
1666///
1667/// An `ExitStatus` represents every possible disposition of a process.  On Unix this
1668/// is the **wait status**.  It is *not* simply an *exit status* (a value passed to `exit`).
1669///
1670/// For proper error reporting of failed processes, print the value of `ExitStatus` or
1671/// `ExitStatusError` using their implementations of [`Display`](crate::fmt::Display).
1672///
1673/// # Differences from `ExitCode`
1674///
1675/// [`ExitCode`] is intended for terminating the currently running process, via
1676/// the `Termination` trait, in contrast to `ExitStatus`, which represents the
1677/// termination of a child process. These APIs are separate due to platform
1678/// compatibility differences and their expected usage; it is not generally
1679/// possible to exactly reproduce an `ExitStatus` from a child for the current
1680/// process after the fact.
1681///
1682/// [`status`]: Command::status
1683/// [`wait`]: Child::wait
1684//
1685// We speak slightly loosely (here and in various other places in the stdlib docs) about `exit`
1686// vs `_exit`.  Naming of Unix system calls is not standardised across Unices, so terminology is a
1687// matter of convention and tradition.  For clarity we usually speak of `exit`, even when we might
1688// mean an underlying system call such as `_exit`.
1689#[derive(PartialEq, Eq, Clone, Copy, Debug)]
1690#[stable(feature = "process", since = "1.0.0")]
1691pub struct ExitStatus(imp::ExitStatus);
1692
1693/// The default value is one which indicates successful completion.
1694#[stable(feature = "process_exitstatus_default", since = "1.73.0")]
1695impl Default for ExitStatus {
1696    fn default() -> Self {
1697        // Ideally this would be done by ExitCode::default().into() but that is complicated.
1698        ExitStatus::from_inner(imp::ExitStatus::default())
1699    }
1700}
1701
1702/// Allows extension traits within `std`.
1703#[unstable(feature = "sealed", issue = "none")]
1704impl crate::sealed::Sealed for ExitStatus {}
1705
1706impl ExitStatus {
1707    /// Was termination successful?  Returns a `Result`.
1708    ///
1709    /// # Examples
1710    ///
1711    /// ```
1712    /// #![feature(exit_status_error)]
1713    /// # if cfg!(unix) {
1714    /// use std::process::Command;
1715    ///
1716    /// let status = Command::new("ls")
1717    ///     .arg("/dev/nonexistent")
1718    ///     .status()
1719    ///     .expect("ls could not be executed");
1720    ///
1721    /// println!("ls: {status}");
1722    /// status.exit_ok().expect_err("/dev/nonexistent could be listed!");
1723    /// # } // cfg!(unix)
1724    /// ```
1725    #[unstable(feature = "exit_status_error", issue = "84908")]
1726    pub fn exit_ok(&self) -> Result<(), ExitStatusError> {
1727        self.0.exit_ok().map_err(ExitStatusError)
1728    }
1729
1730    /// Was termination successful? Signal termination is not considered a
1731    /// success, and success is defined as a zero exit status.
1732    ///
1733    /// # Examples
1734    ///
1735    /// ```rust,no_run
1736    /// use std::process::Command;
1737    ///
1738    /// let status = Command::new("mkdir")
1739    ///     .arg("projects")
1740    ///     .status()
1741    ///     .expect("failed to execute mkdir");
1742    ///
1743    /// if status.success() {
1744    ///     println!("'projects/' directory created");
1745    /// } else {
1746    ///     println!("failed to create 'projects/' directory: {status}");
1747    /// }
1748    /// ```
1749    #[must_use]
1750    #[stable(feature = "process", since = "1.0.0")]
1751    pub fn success(&self) -> bool {
1752        self.0.exit_ok().is_ok()
1753    }
1754
1755    /// Returns the exit code of the process, if any.
1756    ///
1757    /// In Unix terms the return value is the **exit status**: the value passed to `exit`, if the
1758    /// process finished by calling `exit`.  Note that on Unix the exit status is truncated to 8
1759    /// bits, and that values that didn't come from a program's call to `exit` may be invented by the
1760    /// runtime system (often, for example, 255, 254, 127 or 126).
1761    ///
1762    /// On Unix, this will return `None` if the process was terminated by a signal.
1763    /// [`ExitStatusExt`](crate::os::unix::process::ExitStatusExt) is an
1764    /// extension trait for extracting any such signal, and other details, from the `ExitStatus`.
1765    ///
1766    /// # Examples
1767    ///
1768    /// ```no_run
1769    /// use std::process::Command;
1770    ///
1771    /// let status = Command::new("mkdir")
1772    ///     .arg("projects")
1773    ///     .status()
1774    ///     .expect("failed to execute mkdir");
1775    ///
1776    /// match status.code() {
1777    ///     Some(code) => println!("Exited with status code: {code}"),
1778    ///     None => println!("Process terminated by signal")
1779    /// }
1780    /// ```
1781    #[must_use]
1782    #[stable(feature = "process", since = "1.0.0")]
1783    pub fn code(&self) -> Option<i32> {
1784        self.0.code()
1785    }
1786}
1787
1788impl AsInner<imp::ExitStatus> for ExitStatus {
1789    #[inline]
1790    fn as_inner(&self) -> &imp::ExitStatus {
1791        &self.0
1792    }
1793}
1794
1795impl FromInner<imp::ExitStatus> for ExitStatus {
1796    fn from_inner(s: imp::ExitStatus) -> ExitStatus {
1797        ExitStatus(s)
1798    }
1799}
1800
1801#[stable(feature = "process", since = "1.0.0")]
1802impl fmt::Display for ExitStatus {
1803    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1804        self.0.fmt(f)
1805    }
1806}
1807
1808/// Allows extension traits within `std`.
1809#[unstable(feature = "sealed", issue = "none")]
1810impl crate::sealed::Sealed for ExitStatusError {}
1811
1812/// Describes the result of a process after it has failed
1813///
1814/// Produced by the [`.exit_ok`](ExitStatus::exit_ok) method on [`ExitStatus`].
1815///
1816/// # Examples
1817///
1818/// ```
1819/// #![feature(exit_status_error)]
1820/// # if cfg!(unix) {
1821/// use std::process::{Command, ExitStatusError};
1822///
1823/// fn run(cmd: &str) -> Result<(),ExitStatusError> {
1824///     Command::new(cmd).status().unwrap().exit_ok()?;
1825///     Ok(())
1826/// }
1827///
1828/// run("true").unwrap();
1829/// run("false").unwrap_err();
1830/// # } // cfg!(unix)
1831/// ```
1832#[derive(PartialEq, Eq, Clone, Copy, Debug)]
1833#[unstable(feature = "exit_status_error", issue = "84908")]
1834// The definition of imp::ExitStatusError should ideally be such that
1835// Result<(), imp::ExitStatusError> has an identical representation to imp::ExitStatus.
1836pub struct ExitStatusError(imp::ExitStatusError);
1837
1838#[unstable(feature = "exit_status_error", issue = "84908")]
1839impl ExitStatusError {
1840    /// Reports the exit code, if applicable, from an `ExitStatusError`.
1841    ///
1842    /// In Unix terms the return value is the **exit status**: the value passed to `exit`, if the
1843    /// process finished by calling `exit`.  Note that on Unix the exit status is truncated to 8
1844    /// bits, and that values that didn't come from a program's call to `exit` may be invented by the
1845    /// runtime system (often, for example, 255, 254, 127 or 126).
1846    ///
1847    /// On Unix, this will return `None` if the process was terminated by a signal.  If you want to
1848    /// handle such situations specially, consider using methods from
1849    /// [`ExitStatusExt`](crate::os::unix::process::ExitStatusExt).
1850    ///
1851    /// If the process finished by calling `exit` with a nonzero value, this will return
1852    /// that exit status.
1853    ///
1854    /// If the error was something else, it will return `None`.
1855    ///
1856    /// If the process exited successfully (ie, by calling `exit(0)`), there is no
1857    /// `ExitStatusError`.  So the return value from `ExitStatusError::code()` is always nonzero.
1858    ///
1859    /// # Examples
1860    ///
1861    /// ```
1862    /// #![feature(exit_status_error)]
1863    /// # #[cfg(unix)] {
1864    /// use std::process::Command;
1865    ///
1866    /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
1867    /// assert_eq!(bad.code(), Some(1));
1868    /// # } // #[cfg(unix)]
1869    /// ```
1870    #[must_use]
1871    pub fn code(&self) -> Option<i32> {
1872        self.code_nonzero().map(Into::into)
1873    }
1874
1875    /// Reports the exit code, if applicable, from an `ExitStatusError`, as a [`NonZero`].
1876    ///
1877    /// This is exactly like [`code()`](Self::code), except that it returns a <code>[NonZero]<[i32]></code>.
1878    ///
1879    /// Plain `code`, returning a plain integer, is provided because it is often more convenient.
1880    /// The returned value from `code()` is indeed also nonzero; use `code_nonzero()` when you want
1881    /// a type-level guarantee of nonzeroness.
1882    ///
1883    /// # Examples
1884    ///
1885    /// ```
1886    /// #![feature(exit_status_error)]
1887    ///
1888    /// # if cfg!(unix) {
1889    /// use std::num::NonZero;
1890    /// use std::process::Command;
1891    ///
1892    /// let bad = Command::new("false").status().unwrap().exit_ok().unwrap_err();
1893    /// assert_eq!(bad.code_nonzero().unwrap(), NonZero::new(1).unwrap());
1894    /// # } // cfg!(unix)
1895    /// ```
1896    #[must_use]
1897    pub fn code_nonzero(&self) -> Option<NonZero<i32>> {
1898        self.0.code()
1899    }
1900
1901    /// Converts an `ExitStatusError` (back) to an `ExitStatus`.
1902    #[must_use]
1903    pub fn into_status(&self) -> ExitStatus {
1904        ExitStatus(self.0.into())
1905    }
1906}
1907
1908#[unstable(feature = "exit_status_error", issue = "84908")]
1909impl From<ExitStatusError> for ExitStatus {
1910    fn from(error: ExitStatusError) -> Self {
1911        Self(error.0.into())
1912    }
1913}
1914
1915#[unstable(feature = "exit_status_error", issue = "84908")]
1916impl fmt::Display for ExitStatusError {
1917    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1918        write!(f, "process exited unsuccessfully: {}", self.into_status())
1919    }
1920}
1921
1922#[unstable(feature = "exit_status_error", issue = "84908")]
1923impl crate::error::Error for ExitStatusError {}
1924
1925/// This type represents the status code the current process can return
1926/// to its parent under normal termination.
1927///
1928/// `ExitCode` is intended to be consumed only by the standard library (via
1929/// [`Termination::report()`]). For forwards compatibility with potentially
1930/// unusual targets, this type currently does not provide `Eq`, `Hash`, or
1931/// access to the raw value. This type does provide `PartialEq` for
1932/// comparison, but note that there may potentially be multiple failure
1933/// codes, some of which will _not_ compare equal to `ExitCode::FAILURE`.
1934/// The standard library provides the canonical `SUCCESS` and `FAILURE`
1935/// exit codes as well as `From<u8> for ExitCode` for constructing other
1936/// arbitrary exit codes.
1937///
1938/// # Portability
1939///
1940/// Numeric values used in this type don't have portable meanings, and
1941/// different platforms may mask different amounts of them.
1942///
1943/// For the platform's canonical successful and unsuccessful codes, see
1944/// the [`SUCCESS`] and [`FAILURE`] associated items.
1945///
1946/// [`SUCCESS`]: ExitCode::SUCCESS
1947/// [`FAILURE`]: ExitCode::FAILURE
1948///
1949/// # Differences from `ExitStatus`
1950///
1951/// `ExitCode` is intended for terminating the currently running process, via
1952/// the `Termination` trait, in contrast to [`ExitStatus`], which represents the
1953/// termination of a child process. These APIs are separate due to platform
1954/// compatibility differences and their expected usage; it is not generally
1955/// possible to exactly reproduce an `ExitStatus` from a child for the current
1956/// process after the fact.
1957///
1958/// # Examples
1959///
1960/// `ExitCode` can be returned from the `main` function of a crate, as it implements
1961/// [`Termination`]:
1962///
1963/// ```
1964/// use std::process::ExitCode;
1965/// # fn check_foo() -> bool { true }
1966///
1967/// fn main() -> ExitCode {
1968///     if !check_foo() {
1969///         return ExitCode::from(42);
1970///     }
1971///
1972///     ExitCode::SUCCESS
1973/// }
1974/// ```
1975#[derive(Clone, Copy, Debug, PartialEq)]
1976#[stable(feature = "process_exitcode", since = "1.61.0")]
1977pub struct ExitCode(imp::ExitCode);
1978
1979/// Allows extension traits within `std`.
1980#[unstable(feature = "sealed", issue = "none")]
1981impl crate::sealed::Sealed for ExitCode {}
1982
1983#[stable(feature = "process_exitcode", since = "1.61.0")]
1984impl ExitCode {
1985    /// The canonical `ExitCode` for successful termination on this platform.
1986    ///
1987    /// Note that a `()`-returning `main` implicitly results in a successful
1988    /// termination, so there's no need to return this from `main` unless
1989    /// you're also returning other possible codes.
1990    #[stable(feature = "process_exitcode", since = "1.61.0")]
1991    pub const SUCCESS: ExitCode = ExitCode(imp::ExitCode::SUCCESS);
1992
1993    /// The canonical `ExitCode` for unsuccessful termination on this platform.
1994    ///
1995    /// If you're only returning this and `SUCCESS` from `main`, consider
1996    /// instead returning `Err(_)` and `Ok(())` respectively, which will
1997    /// return the same codes (but will also `eprintln!` the error).
1998    #[stable(feature = "process_exitcode", since = "1.61.0")]
1999    pub const FAILURE: ExitCode = ExitCode(imp::ExitCode::FAILURE);
2000
2001    /// Exit the current process with the given `ExitCode`.
2002    ///
2003    /// Note that this has the same caveats as [`process::exit()`][exit], namely that this function
2004    /// terminates the process immediately, so no destructors on the current stack or any other
2005    /// thread's stack will be run. If a clean shutdown is needed, it is recommended to simply
2006    /// return this ExitCode from the `main` function, as demonstrated in the [type
2007    /// documentation](#examples).
2008    ///
2009    /// # Differences from `process::exit()`
2010    ///
2011    /// `process::exit()` accepts any `i32` value as the exit code for the process; however, there
2012    /// are platforms that only use a subset of that value (see [`process::exit` platform-specific
2013    /// behavior][exit#platform-specific-behavior]). `ExitCode` exists because of this; only
2014    /// `ExitCode`s that are supported by a majority of our platforms can be created, so those
2015    /// problems don't exist (as much) with this method.
2016    ///
2017    /// # Examples
2018    ///
2019    /// ```
2020    /// #![feature(exitcode_exit_method)]
2021    /// # use std::process::ExitCode;
2022    /// # use std::fmt;
2023    /// # enum UhOhError { GenericProblem, Specific, WithCode { exit_code: ExitCode, _x: () } }
2024    /// # impl fmt::Display for UhOhError {
2025    /// #     fn fmt(&self, _: &mut fmt::Formatter<'_>) -> fmt::Result { unimplemented!() }
2026    /// # }
2027    /// // there's no way to gracefully recover from an UhOhError, so we just
2028    /// // print a message and exit
2029    /// fn handle_unrecoverable_error(err: UhOhError) -> ! {
2030    ///     eprintln!("UH OH! {err}");
2031    ///     let code = match err {
2032    ///         UhOhError::GenericProblem => ExitCode::FAILURE,
2033    ///         UhOhError::Specific => ExitCode::from(3),
2034    ///         UhOhError::WithCode { exit_code, .. } => exit_code,
2035    ///     };
2036    ///     code.exit_process()
2037    /// }
2038    /// ```
2039    #[unstable(feature = "exitcode_exit_method", issue = "97100")]
2040    pub fn exit_process(self) -> ! {
2041        exit(self.to_i32())
2042    }
2043}
2044
2045impl ExitCode {
2046    // This is private/perma-unstable because ExitCode is opaque; we don't know that i32 will serve
2047    // all usecases, for example windows seems to use u32, unix uses the 8-15th bits of an i32, we
2048    // likely want to isolate users anything that could restrict the platform specific
2049    // representation of an ExitCode
2050    //
2051    // More info: https://internals.rust-lang.org/t/mini-pre-rfc-redesigning-process-exitstatus/5426
2052    /// Converts an `ExitCode` into an i32
2053    #[unstable(
2054        feature = "process_exitcode_internals",
2055        reason = "exposed only for libstd",
2056        issue = "none"
2057    )]
2058    #[inline]
2059    #[doc(hidden)]
2060    pub fn to_i32(self) -> i32 {
2061        self.0.as_i32()
2062    }
2063}
2064
2065/// The default value is [`ExitCode::SUCCESS`]
2066#[stable(feature = "process_exitcode_default", since = "1.75.0")]
2067impl Default for ExitCode {
2068    fn default() -> Self {
2069        ExitCode::SUCCESS
2070    }
2071}
2072
2073#[stable(feature = "process_exitcode", since = "1.61.0")]
2074impl From<u8> for ExitCode {
2075    /// Constructs an `ExitCode` from an arbitrary u8 value.
2076    fn from(code: u8) -> Self {
2077        ExitCode(imp::ExitCode::from(code))
2078    }
2079}
2080
2081impl AsInner<imp::ExitCode> for ExitCode {
2082    #[inline]
2083    fn as_inner(&self) -> &imp::ExitCode {
2084        &self.0
2085    }
2086}
2087
2088impl FromInner<imp::ExitCode> for ExitCode {
2089    fn from_inner(s: imp::ExitCode) -> ExitCode {
2090        ExitCode(s)
2091    }
2092}
2093
2094impl Child {
2095    /// Forces the child process to exit. If the child has already exited, `Ok(())`
2096    /// is returned.
2097    ///
2098    /// The mapping to [`ErrorKind`]s is not part of the compatibility contract of the function.
2099    ///
2100    /// This is equivalent to sending a SIGKILL on Unix platforms.
2101    ///
2102    /// # Examples
2103    ///
2104    /// ```no_run
2105    /// use std::process::Command;
2106    ///
2107    /// let mut command = Command::new("yes");
2108    /// if let Ok(mut child) = command.spawn() {
2109    ///     child.kill().expect("command couldn't be killed");
2110    /// } else {
2111    ///     println!("yes command didn't start");
2112    /// }
2113    /// ```
2114    ///
2115    /// [`ErrorKind`]: io::ErrorKind
2116    /// [`InvalidInput`]: io::ErrorKind::InvalidInput
2117    #[stable(feature = "process", since = "1.0.0")]
2118    pub fn kill(&mut self) -> io::Result<()> {
2119        self.handle.kill()
2120    }
2121
2122    /// Returns the OS-assigned process identifier associated with this child.
2123    ///
2124    /// # Examples
2125    ///
2126    /// ```no_run
2127    /// use std::process::Command;
2128    ///
2129    /// let mut command = Command::new("ls");
2130    /// if let Ok(child) = command.spawn() {
2131    ///     println!("Child's ID is {}", child.id());
2132    /// } else {
2133    ///     println!("ls command didn't start");
2134    /// }
2135    /// ```
2136    #[must_use]
2137    #[stable(feature = "process_id", since = "1.3.0")]
2138    pub fn id(&self) -> u32 {
2139        self.handle.id()
2140    }
2141
2142    /// Waits for the child to exit completely, returning the status that it
2143    /// exited with. This function will continue to have the same return value
2144    /// after it has been called at least once.
2145    ///
2146    /// The stdin handle to the child process, if any, will be closed
2147    /// before waiting. This helps avoid deadlock: it ensures that the
2148    /// child does not block waiting for input from the parent, while
2149    /// the parent waits for the child to exit.
2150    ///
2151    /// # Examples
2152    ///
2153    /// ```no_run
2154    /// use std::process::Command;
2155    ///
2156    /// let mut command = Command::new("ls");
2157    /// if let Ok(mut child) = command.spawn() {
2158    ///     child.wait().expect("command wasn't running");
2159    ///     println!("Child has finished its execution!");
2160    /// } else {
2161    ///     println!("ls command didn't start");
2162    /// }
2163    /// ```
2164    #[stable(feature = "process", since = "1.0.0")]
2165    pub fn wait(&mut self) -> io::Result<ExitStatus> {
2166        drop(self.stdin.take());
2167        self.handle.wait().map(ExitStatus)
2168    }
2169
2170    /// Attempts to collect the exit status of the child if it has already
2171    /// exited.
2172    ///
2173    /// This function will not block the calling thread and will only
2174    /// check to see if the child process has exited or not. If the child has
2175    /// exited then on Unix the process ID is reaped. This function is
2176    /// guaranteed to repeatedly return a successful exit status so long as the
2177    /// child has already exited.
2178    ///
2179    /// If the child has exited, then `Ok(Some(status))` is returned. If the
2180    /// exit status is not available at this time then `Ok(None)` is returned.
2181    /// If an error occurs, then that error is returned.
2182    ///
2183    /// Note that unlike `wait`, this function will not attempt to drop stdin.
2184    ///
2185    /// # Examples
2186    ///
2187    /// ```no_run
2188    /// use std::process::Command;
2189    ///
2190    /// let mut child = Command::new("ls").spawn()?;
2191    ///
2192    /// match child.try_wait() {
2193    ///     Ok(Some(status)) => println!("exited with: {status}"),
2194    ///     Ok(None) => {
2195    ///         println!("status not ready yet, let's really wait");
2196    ///         let res = child.wait();
2197    ///         println!("result: {res:?}");
2198    ///     }
2199    ///     Err(e) => println!("error attempting to wait: {e}"),
2200    /// }
2201    /// # std::io::Result::Ok(())
2202    /// ```
2203    #[stable(feature = "process_try_wait", since = "1.18.0")]
2204    pub fn try_wait(&mut self) -> io::Result<Option<ExitStatus>> {
2205        Ok(self.handle.try_wait()?.map(ExitStatus))
2206    }
2207
2208    /// Simultaneously waits for the child to exit and collect all remaining
2209    /// output on the stdout/stderr handles, returning an `Output`
2210    /// instance.
2211    ///
2212    /// The stdin handle to the child process, if any, will be closed
2213    /// before waiting. This helps avoid deadlock: it ensures that the
2214    /// child does not block waiting for input from the parent, while
2215    /// the parent waits for the child to exit.
2216    ///
2217    /// By default, stdin, stdout and stderr are inherited from the parent.
2218    /// In order to capture the output into this `Result<Output>` it is
2219    /// necessary to create new pipes between parent and child. Use
2220    /// `stdout(Stdio::piped())` or `stderr(Stdio::piped())`, respectively.
2221    ///
2222    /// # Examples
2223    ///
2224    /// ```should_panic
2225    /// use std::process::{Command, Stdio};
2226    ///
2227    /// let child = Command::new("/bin/cat")
2228    ///     .arg("file.txt")
2229    ///     .stdout(Stdio::piped())
2230    ///     .spawn()
2231    ///     .expect("failed to execute child");
2232    ///
2233    /// let output = child
2234    ///     .wait_with_output()
2235    ///     .expect("failed to wait on child");
2236    ///
2237    /// assert!(output.status.success());
2238    /// ```
2239    ///
2240    #[stable(feature = "process", since = "1.0.0")]
2241    pub fn wait_with_output(mut self) -> io::Result<Output> {
2242        drop(self.stdin.take());
2243
2244        let (mut stdout, mut stderr) = (Vec::new(), Vec::new());
2245        match (self.stdout.take(), self.stderr.take()) {
2246            (None, None) => {}
2247            (Some(mut out), None) => {
2248                let res = out.read_to_end(&mut stdout);
2249                res.unwrap();
2250            }
2251            (None, Some(mut err)) => {
2252                let res = err.read_to_end(&mut stderr);
2253                res.unwrap();
2254            }
2255            (Some(out), Some(err)) => {
2256                let res = read2(out.inner, &mut stdout, err.inner, &mut stderr);
2257                res.unwrap();
2258            }
2259        }
2260
2261        let status = self.wait()?;
2262        Ok(Output { status, stdout, stderr })
2263    }
2264}
2265
2266/// Terminates the current process with the specified exit code.
2267///
2268/// This function will never return and will immediately terminate the current
2269/// process. The exit code is passed through to the underlying OS and will be
2270/// available for consumption by another process.
2271///
2272/// Note that because this function never returns, and that it terminates the
2273/// process, no destructors on the current stack or any other thread's stack
2274/// will be run. If a clean shutdown is needed it is recommended to only call
2275/// this function at a known point where there are no more destructors left
2276/// to run; or, preferably, simply return a type implementing [`Termination`]
2277/// (such as [`ExitCode`] or `Result`) from the `main` function and avoid this
2278/// function altogether:
2279///
2280/// ```
2281/// # use std::io::Error as MyError;
2282/// fn main() -> Result<(), MyError> {
2283///     // ...
2284///     Ok(())
2285/// }
2286/// ```
2287///
2288/// In its current implementation, this function will execute exit handlers registered with `atexit`
2289/// as well as other platform-specific exit handlers (e.g. `fini` sections of ELF shared objects).
2290/// This means that Rust requires that all exit handlers are safe to execute at any time. In
2291/// particular, if an exit handler cleans up some state that might be concurrently accessed by other
2292/// threads, it is required that the exit handler performs suitable synchronization with those
2293/// threads. (The alternative to this requirement would be to not run exit handlers at all, which is
2294/// considered undesirable. Note that returning from `main` also calls `exit`, so making `exit` an
2295/// unsafe operation is not an option.)
2296///
2297/// ## Platform-specific behavior
2298///
2299/// **Unix**: On Unix-like platforms, it is unlikely that all 32 bits of `exit`
2300/// will be visible to a parent process inspecting the exit code. On most
2301/// Unix-like platforms, only the eight least-significant bits are considered.
2302///
2303/// For example, the exit code for this example will be `0` on Linux, but `256`
2304/// on Windows:
2305///
2306/// ```no_run
2307/// use std::process;
2308///
2309/// process::exit(0x0100);
2310/// ```
2311#[stable(feature = "rust1", since = "1.0.0")]
2312#[cfg_attr(not(test), rustc_diagnostic_item = "process_exit")]
2313pub fn exit(code: i32) -> ! {
2314    crate::rt::cleanup();
2315    crate::sys::os::exit(code)
2316}
2317
2318/// Terminates the process in an abnormal fashion.
2319///
2320/// The function will never return and will immediately terminate the current
2321/// process in a platform specific "abnormal" manner. As a consequence,
2322/// no destructors on the current stack or any other thread's stack
2323/// will be run, Rust IO buffers (eg, from `BufWriter`) will not be flushed,
2324/// and C stdio buffers will (on most platforms) not be flushed.
2325///
2326/// This is in contrast to the default behavior of [`panic!`] which unwinds
2327/// the current thread's stack and calls all destructors.
2328/// When `panic="abort"` is set, either as an argument to `rustc` or in a
2329/// crate's Cargo.toml, [`panic!`] and `abort` are similar. However,
2330/// [`panic!`] will still call the [panic hook] while `abort` will not.
2331///
2332/// If a clean shutdown is needed it is recommended to only call
2333/// this function at a known point where there are no more destructors left
2334/// to run.
2335///
2336/// The process's termination will be similar to that from the C `abort()`
2337/// function.  On Unix, the process will terminate with signal `SIGABRT`, which
2338/// typically means that the shell prints "Aborted".
2339///
2340/// # Examples
2341///
2342/// ```no_run
2343/// use std::process;
2344///
2345/// fn main() {
2346///     println!("aborting");
2347///
2348///     process::abort();
2349///
2350///     // execution never gets here
2351/// }
2352/// ```
2353///
2354/// The `abort` function terminates the process, so the destructor will not
2355/// get run on the example below:
2356///
2357/// ```no_run
2358/// use std::process;
2359///
2360/// struct HasDrop;
2361///
2362/// impl Drop for HasDrop {
2363///     fn drop(&mut self) {
2364///         println!("This will never be printed!");
2365///     }
2366/// }
2367///
2368/// fn main() {
2369///     let _x = HasDrop;
2370///     process::abort();
2371///     // the destructor implemented for HasDrop will never get run
2372/// }
2373/// ```
2374///
2375/// [panic hook]: crate::panic::set_hook
2376#[stable(feature = "process_abort", since = "1.17.0")]
2377#[cold]
2378pub fn abort() -> ! {
2379    crate::sys::abort_internal();
2380}
2381
2382/// Returns the OS-assigned process identifier associated with this process.
2383///
2384/// # Examples
2385///
2386/// ```no_run
2387/// use std::process;
2388///
2389/// println!("My pid is {}", process::id());
2390/// ```
2391#[must_use]
2392#[stable(feature = "getpid", since = "1.26.0")]
2393pub fn id() -> u32 {
2394    crate::sys::os::getpid()
2395}
2396
2397/// A trait for implementing arbitrary return types in the `main` function.
2398///
2399/// The C-main function only supports returning integers.
2400/// So, every type implementing the `Termination` trait has to be converted
2401/// to an integer.
2402///
2403/// The default implementations are returning `libc::EXIT_SUCCESS` to indicate
2404/// a successful execution. In case of a failure, `libc::EXIT_FAILURE` is returned.
2405///
2406/// Because different runtimes have different specifications on the return value
2407/// of the `main` function, this trait is likely to be available only on
2408/// standard library's runtime for convenience. Other runtimes are not required
2409/// to provide similar functionality.
2410#[cfg_attr(not(any(test, doctest)), lang = "termination")]
2411#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2412#[rustc_on_unimplemented(on(
2413    cause = "MainFunctionType",
2414    message = "`main` has invalid return type `{Self}`",
2415    label = "`main` can only return types that implement `{Termination}`"
2416))]
2417pub trait Termination {
2418    /// Is called to get the representation of the value as status code.
2419    /// This status code is returned to the operating system.
2420    #[stable(feature = "termination_trait_lib", since = "1.61.0")]
2421    fn report(self) -> ExitCode;
2422}
2423
2424#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2425impl Termination for () {
2426    #[inline]
2427    fn report(self) -> ExitCode {
2428        ExitCode::SUCCESS
2429    }
2430}
2431
2432#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2433impl Termination for ! {
2434    fn report(self) -> ExitCode {
2435        self
2436    }
2437}
2438
2439#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2440impl Termination for Infallible {
2441    fn report(self) -> ExitCode {
2442        match self {}
2443    }
2444}
2445
2446#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2447impl Termination for ExitCode {
2448    #[inline]
2449    fn report(self) -> ExitCode {
2450        self
2451    }
2452}
2453
2454#[stable(feature = "termination_trait_lib", since = "1.61.0")]
2455impl<T: Termination, E: fmt::Debug> Termination for Result<T, E> {
2456    fn report(self) -> ExitCode {
2457        match self {
2458            Ok(val) => val.report(),
2459            Err(err) => {
2460                io::attempt_print_to_stderr(format_args_nl!("Error: {err:?}"));
2461                ExitCode::FAILURE
2462            }
2463        }
2464    }
2465}