# Struct std::fs::File

1.0.0 · source ·

    pub struct File { /* private fields */ }

Expand description

An object providing access to an open file on the filesystem.

An instance of a `File` can be read and/or written depending on what options it was opened with. Files also implement `Seek` to alter the logical cursor that the file contains internally.

Files are automatically closed when they go out of scope. Errors detected on closing are ignored by the implementation of `Drop`. Use the method `sync_all` if these errors must be manually handled.

## Examples

Creates a new file and write bytes to it (you can also use `write()`):

    use std::fs::File;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let mut file = File::create("foo.txt")?;
        file.write_all(b"Hello, world!")?;
        Ok(())
    }

Run

Read the contents of a file into a `String` (you can also use `read`):

    use std::fs::File;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let mut file = File::open("foo.txt")?;
        let mut contents = String::new();
        file.read_to_string(&mut contents)?;
        assert_eq!(contents, "Hello, world!");
        Ok(())
    }

Run

It can be more efficient to read the contents of a file with a buffered `Read`er. This can be accomplished with `BufReader<R>`:

    use std::fs::File;
    use std::io::BufReader;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let file = File::open("foo.txt")?;
        let mut buf_reader = BufReader::new(file);
        let mut contents = String::new();
        buf_reader.read_to_string(&mut contents)?;
        assert_eq!(contents, "Hello, world!");
        Ok(())
    }

Run

Note that, although read and write methods require a `&mut File`, because of the interfaces for `Read` and `Write`, the holder of a `&File` can still modify the file, either through methods that take `&File` or by retrieving the underlying OS object and modifying the file that way. Additionally, many operating systems allow concurrent modification of files by different processes. Avoid assuming that holding a `&File` means that the file will not change.

## Platform-specific behavior

On Windows, the implementation of `Read` and `Write` traits for `File` perform synchronous I/O operations. Therefore the underlying file must not have been opened for asynchronous I/O (e.g. by using `FILE_FLAG_OVERLAPPED`).

## Implementations§

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### impl File

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#### pub fn open<P: AsRef<Path>>(path: P) -> Result<File>

Attempts to open a file in read-only mode.

See the `OpenOptions::open` method for more details.

If you only need to read the entire file contents, consider `std::fs::read()` or `std::fs::read_to_string()` instead.

##### Errors

This function will return an error if `path` does not already exist. Other errors may also be returned according to `OpenOptions::open`.

##### Examples

    use std::fs::File;
    use std::io::Read;

    fn main() -> std::io::Result<()> {
        let mut f = File::open("foo.txt")?;
        let mut data = vec![];
        f.read_to_end(&mut data)?;
        Ok(())
    }

Run
source

#### pub fn create<P: AsRef<Path>>(path: P) -> Result<File>

Opens a file in write-only mode.

This function will create a file if it does not exist, and will truncate it if it does.

Depending on the platform, this function may fail if the full directory path does not exist. See the `OpenOptions::open` function for more details.

See also `std::fs::write()` for a simple function to create a file with a given data.

##### Examples

    use std::fs::File;
    use std::io::Write;

    fn main() -> std::io::Result<()> {
        let mut f = File::create("foo.txt")?;
        f.write_all(&1234_u32.to_be_bytes())?;
        Ok(())
    }

Run
source

#### pub fn create_new<P: AsRef<Path>>(path: P) -> Result<File>

🔬This is a nightly-only experimental API. (`file_create_new` #105135)

Creates a new file in read-write mode; error if the file exists.

This function will create a file if it does not exist, or return an error if it does. This way, if the call succeeds, the file returned is guaranteed to be new.

This option is useful because it is atomic. Otherwise between checking whether a file exists and creating a new one, the file may have been created by another process (a TOCTOU race condition / attack).

This can also be written using `File::options().read(true).write(true).create_new(true).open(...)`.

##### Examples

    #![feature(file_create_new)]

    use std::fs::File;
    use std::io::Write;

    fn main() -> std::io::Result<()> {
        let mut f = File::create_new("foo.txt")?;
        f.write_all("Hello, world!".as_bytes())?;
        Ok(())
    }

Run
1.58.0 · source

#### pub fn options() -> OpenOptions

Returns a new OpenOptions object.

This function returns a new OpenOptions object that you can use to open or create a file with specific options if `open()` or `create()` are not appropriate.

It is equivalent to `OpenOptions::new()`, but allows you to write more readable code. Instead of `OpenOptions::new().append(true).open("example.log")`, you can write `File::options().append(true).open("example.log")`. This also avoids the need to import `OpenOptions`.

See the `OpenOptions::new` function for more details.

##### Examples

    use std::fs::File;
    use std::io::Write;

    fn main() -> std::io::Result<()> {
        let mut f = File::options().append(true).open("example.log")?;
        writeln!(&mut f, "new line")?;
        Ok(())
    }

Run
source

#### pub fn sync_all(&self) -> Result<()>

Attempts to sync all OS-internal metadata to disk.

This function will attempt to ensure that all in-memory data reaches the filesystem before returning.

This can be used to handle errors that would otherwise only be caught when the `File` is closed. Dropping a file will ignore errors in synchronizing this in-memory data.

##### Examples

    use std::fs::File;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let mut f = File::create("foo.txt")?;
        f.write_all(b"Hello, world!")?;

        f.sync_all()?;
        Ok(())
    }

Run
source

#### pub fn sync_data(&self) -> Result<()>

This function is similar to `sync_all`, except that it might not synchronize file metadata to the filesystem.

This is intended for use cases that must synchronize content, but don’t need the metadata on disk. The goal of this method is to reduce disk operations.

Note that some platforms may simply implement this in terms of `sync_all`.

##### Examples

    use std::fs::File;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let mut f = File::create("foo.txt")?;
        f.write_all(b"Hello, world!")?;

        f.sync_data()?;
        Ok(())
    }

Run
source

#### pub fn set_len(&self, size: u64) -> Result<()>

Truncates or extends the underlying file, updating the size of this file to become `size`.

If the `size` is less than the current file’s size, then the file will be shrunk. If it is greater than the current file’s size, then the file will be extended to `size` and have all of the intermediate data filled in with 0s.

The file’s cursor isn’t changed. In particular, if the cursor was at the end and the file is shrunk using this operation, the cursor will now be past the end.

##### Errors

This function will return an error if the file is not opened for writing. Also, `std::io::ErrorKind::InvalidInput` will be returned if the desired length would cause an overflow due to the implementation specifics.

##### Examples

    use std::fs::File;

    fn main() -> std::io::Result<()> {
        let mut f = File::create("foo.txt")?;
        f.set_len(10)?;
        Ok(())
    }

Run

Note that this method alters the content of the underlying file, even though it takes `&self` rather than `&mut self`.

source

#### pub fn metadata(&self) -> Result<Metadata>

Queries metadata about the underlying file.

##### Examples

    use std::fs::File;

    fn main() -> std::io::Result<()> {
        let mut f = File::open("foo.txt")?;
        let metadata = f.metadata()?;
        Ok(())
    }

Run
1.9.0 · source

#### pub fn try_clone(&self) -> Result<File>

Creates a new `File` instance that shares the same underlying file handle as the existing `File` instance. Reads, writes, and seeks will affect both `File` instances simultaneously.

##### Examples

Creates two handles for a file named `foo.txt`:

    use std::fs::File;

    fn main() -> std::io::Result<()> {
        let mut file = File::open("foo.txt")?;
        let file_copy = file.try_clone()?;
        Ok(())
    }

Run

Assuming there’s a file named `foo.txt` with contents `abcdef\n`, create two handles, seek one of them, and read the remaining bytes from the other handle:

    use std::fs::File;
    use std::io::SeekFrom;
    use std::io::prelude::*;

    fn main() -> std::io::Result<()> {
        let mut file = File::open("foo.txt")?;
        let mut file_copy = file.try_clone()?;

        file.seek(SeekFrom::Start(3))?;

        let mut contents = vec![];
        file_copy.read_to_end(&mut contents)?;
        assert_eq!(contents, b"def\n");
        Ok(())
    }

Run
1.16.0 · source

#### pub fn set_permissions(&self, perm: Permissions) -> Result<()>

Changes the permissions on the underlying file.

##### Platform-specific behavior

This function currently corresponds to the `fchmod` function on Unix and the `SetFileInformationByHandle` function on Windows. Note that, this may change in the future.

##### Errors

This function will return an error if the user lacks permission change attributes on the underlying file. It may also return an error in other os-specific unspecified cases.

##### Examples

    fn main() -> std::io::Result<()> {
        use std::fs::File;

        let file = File::open("foo.txt")?;
        let mut perms = file.metadata()?.permissions();
        perms.set_readonly(true);
        file.set_permissions(perms)?;
        Ok(())
    }

Run

Note that this method alters the permissions of the underlying file, even though it takes `&self` rather than `&mut self`.

1.75.0 · source

#### pub fn set_times(&self, times: FileTimes) -> Result<()>

Changes the timestamps of the underlying file.

##### Platform-specific behavior

This function currently corresponds to the `futimens` function on Unix (falling back to `futimes` on macOS before 10.13) and the `SetFileTime` function on Windows. Note that this may change in the future.

##### Errors

This function will return an error if the user lacks permission to change timestamps on the underlying file. It may also return an error in other os-specific unspecified cases.

This function may return an error if the operating system lacks support to change one or more of the timestamps set in the `FileTimes` structure.

##### Examples

    fn main() -> std::io::Result<()> {
        use std::fs::{self, File, FileTimes};

        let src = fs::metadata("src")?;
        let dest = File::options().write(true).open("dest")?;
        let times = FileTimes::new()
            .set_accessed(src.accessed()?)
            .set_modified(src.modified()?);
        dest.set_times(times)?;
        Ok(())
    }

Run
1.75.0 · source

#### pub fn set_modified(&self, time: SystemTime) -> Result<()>

Changes the modification time of the underlying file.

This is an alias for `set_times(FileTimes::new().set_modified(time))`.

## Trait Implementations§

1.63.0 · source§

### impl AsFd for File

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#### fn as_fd(&self) -> BorrowedFd<'_>

Borrows the file descriptor. Read more
1.63.0 · source§

### impl AsHandle for File

Available on Windows only.
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#### fn as_handle(&self) -> BorrowedHandle<'_>

Borrows the handle. Read more
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### impl AsRawFd for File

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#### fn as_raw_fd(&self) -> RawFd

Extracts the raw file descriptor. Read more
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### impl AsRawHandle for File

Available on Windows only.
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#### fn as_raw_handle(&self) -> RawHandle

Extracts the raw handle. Read more
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### impl Debug for File

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

Formats the value using the given formatter. Read more
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### impl FileExt for File

Available on WASI only.
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#### fn read_vectored_at( &self, bufs: &mut [IoSliceMut<'_>], offset: u64 ) -> Result<usize>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Reads a number of bytes starting from a given offset. Read more
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#### fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> Result<usize>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Writes a number of bytes starting from a given offset. Read more
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#### fn tell(&self) -> Result<u64>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Returns the current position within the file. Read more
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#### fn fdstat_set_flags(&self, flags: u16) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Adjust the flags associated with this file. Read more
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#### fn fdstat_set_rights(&self, rights: u64, inheriting: u64) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Adjust the rights associated with this file. Read more
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#### fn advise(&self, offset: u64, len: u64, advice: u8) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Provide file advisory information on a file descriptor. Read more
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#### fn allocate(&self, offset: u64, len: u64) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Force the allocation of space in a file. Read more
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#### fn create_directory<P: AsRef<Path>>(&self, dir: P) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Create a directory. Read more
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#### fn read_link<P: AsRef<Path>>(&self, path: P) -> Result<PathBuf>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Read the contents of a symbolic link. Read more
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#### fn metadata_at<P: AsRef<Path>>( &self, lookup_flags: u32, path: P ) -> Result<Metadata>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Return the attributes of a file or directory. Read more
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#### fn remove_file<P: AsRef<Path>>(&self, path: P) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Unlink a file. Read more
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#### fn remove_directory<P: AsRef<Path>>(&self, path: P) -> Result<()>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Remove a directory. Read more
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#### fn read_at(&self, buf: &mut [u8], offset: u64) -> Result<usize>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Reads a number of bytes starting from a given offset. Read more
1.33.0 · source§

#### fn read_exact_at(&self, buf: &mut [u8], offset: u64) -> Result<()>

Reads the exact number of byte required to fill `buf` from the given offset. Read more
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#### fn write_at(&self, buf: &[u8], offset: u64) -> Result<usize>

🔬This is a nightly-only experimental API. (`wasi_ext` #71213)
Writes a number of bytes starting from a given offset. Read more
1.33.0 · source§

#### fn write_all_at(&self, buf: &[u8], offset: u64) -> Result<()>

Attempts to write an entire buffer starting from a given offset. Read more
1.15.0 · source§

### impl FileExt for File

Available on Windows only.
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#### fn seek_read(&self, buf: &mut [u8], offset: u64) -> Result<usize>

Seeks to a given position and reads a number of bytes. Read more
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#### fn seek_write(&self, buf: &[u8], offset: u64) -> Result<usize>

Seeks to a given position and writes a number of bytes. Read more
1.15.0 · source§

### impl FileExt for File

Available on Unix only.
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#### fn read_at(&self, buf: &mut [u8], offset: u64) -> Result<usize>

Reads a number of bytes starting from a given offset. Read more
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#### fn read_vectored_at( &self, bufs: &mut [IoSliceMut<'_>], offset: u64 ) -> Result<usize>

🔬This is a nightly-only experimental API. (`unix_file_vectored_at` #89517)
Like `read_at`, except that it reads into a slice of buffers. Read more
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#### fn write_at(&self, buf: &[u8], offset: u64) -> Result<usize>

Writes a number of bytes starting from a given offset. Read more
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#### fn write_vectored_at(&self, bufs: &[IoSlice<'_>], offset: u64) -> Result<usize>

🔬This is a nightly-only experimental API. (`unix_file_vectored_at` #89517)
Like `write_at`, except that it writes from a slice of buffers. Read more
1.33.0 · source§

#### fn read_exact_at(&self, buf: &mut [u8], offset: u64) -> Result<()>

Reads the exact number of byte required to fill `buf` from the given offset. Read more
1.33.0 · source§

#### fn write_all_at(&self, buf: &[u8], offset: u64) -> Result<()>

Attempts to write an entire buffer starting from a given offset. Read more
1.63.0 · source§

### impl From<File> for OwnedFd

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#### fn from(file: File) -> OwnedFd

Converts to this type from the input type.
1.63.0 · source§

### impl From<File> for OwnedHandle

Available on Windows only.
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#### fn from(file: File) -> OwnedHandle

Converts to this type from the input type.
1.20.0 · source§

### impl From<File> for Stdio

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#### fn from(file: File) -> Stdio

Converts a `File` into a `Stdio`.

##### Examples

`File` will be converted to `Stdio` using `Stdio::from` under the hood.

    use std::fs::File;
    use std::process::Command;

    // With the `foo.txt` file containing "Hello, world!"
    let file = File::open("foo.txt").unwrap();

    let reverse = Command::new("rev")
        .stdin(file)  // Implicit File conversion into a Stdio
        .output()
        .expect("failed reverse command");

    assert_eq!(reverse.stdout, b"!dlrow ,olleH");

Run
1.63.0 · source§

### impl From<OwnedFd> for File

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#### fn from(owned_fd: OwnedFd) -> Self

Converts to this type from the input type.
1.63.0 · source§

### impl From<OwnedHandle> for File

Available on Windows only.
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#### fn from(owned: OwnedHandle) -> Self

Converts to this type from the input type.
1.1.0 · source§

### impl FromRawFd for File

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#### unsafe fn from_raw_fd(fd: RawFd) -> File ⓘ

Constructs a new instance of `Self` from the given raw file descriptor. Read more
1.1.0 · source§

### impl FromRawHandle for File

Available on Windows only.
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#### unsafe fn from_raw_handle(handle: RawHandle) -> File ⓘ

Constructs a new I/O object from the specified raw handle. Read more
1.4.0 · source§

### impl IntoRawFd for File

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#### fn into_raw_fd(self) -> RawFd

Consumes this object, returning the raw underlying file descriptor. Read more
1.4.0 · source§

### impl IntoRawHandle for File

Available on Windows only.
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#### fn into_raw_handle(self) -> RawHandle

Consumes this object, returning the raw underlying handle. Read more
1.70.0 · source§

### impl IsTerminal for File

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#### fn is_terminal(&self) -> bool

Returns `true` if the descriptor/handle refers to a terminal/tty. Read more
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### impl Read for &File

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#### fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
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#### fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like `read`, except that it reads into a slice of buffers. Read more
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#### fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (`read_buf` #78485)
Pull some bytes from this source into the specified buffer. Read more
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#### fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Read`er has an efficient `read_vectored` implementation. Read more
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#### fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Read all bytes until EOF in this source, placing them into `buf`. Read more
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#### fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Read all bytes until EOF in this source, appending them to `buf`. Read more
1.6.0 · source§

#### fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Read the exact number of bytes required to fill `buf`. Read more
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#### fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (`read_buf` #78485)
Read the exact number of bytes required to fill `cursor`. Read more
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#### fn by_ref(&mut self) -> &mut Self where Self: Sized,

Creates a “by reference” adaptor for this instance of `Read`. Read more
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#### fn bytes(self) -> Bytes<Self> ⓘwhere Self: Sized,

Transforms this `Read` instance to an `Iterator` over its bytes. Read more
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#### fn chain<R: Read>(self, next: R) -> Chain<Self, R> ⓘwhere Self: Sized,

Creates an adapter which will chain this stream with another. Read more
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#### fn take(self, limit: u64) -> Take<Self> ⓘwhere Self: Sized,

Creates an adapter which will read at most `limit` bytes from it. Read more
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### impl Read for File

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#### fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more
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#### fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like `read`, except that it reads into a slice of buffers. Read more
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#### fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (`read_buf` #78485)
Pull some bytes from this source into the specified buffer. Read more
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#### fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Read`er has an efficient `read_vectored` implementation. Read more
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#### fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Read all bytes until EOF in this source, placing them into `buf`. Read more
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#### fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Read all bytes until EOF in this source, appending them to `buf`. Read more
1.6.0 · source§

#### fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Read the exact number of bytes required to fill `buf`. Read more
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#### fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (`read_buf` #78485)
Read the exact number of bytes required to fill `cursor`. Read more
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#### fn by_ref(&mut self) -> &mut Self where Self: Sized,

Creates a “by reference” adaptor for this instance of `Read`. Read more
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#### fn bytes(self) -> Bytes<Self> ⓘwhere Self: Sized,

Transforms this `Read` instance to an `Iterator` over its bytes. Read more
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#### fn chain<R: Read>(self, next: R) -> Chain<Self, R> ⓘwhere Self: Sized,

Creates an adapter which will chain this stream with another. Read more
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#### fn take(self, limit: u64) -> Take<Self> ⓘwhere Self: Sized,

Creates an adapter which will read at most `limit` bytes from it. Read more
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### impl Seek for &File

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#### fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream. Read more
1.55.0 · source§

#### fn rewind(&mut self) -> Result<()>

Rewind to the beginning of a stream. Read more
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#### fn stream_len(&mut self) -> Result<u64>

🔬This is a nightly-only experimental API. (`seek_stream_len` #59359)
Returns the length of this stream (in bytes). Read more
1.51.0 · source§

#### fn stream_position(&mut self) -> Result<u64>

Returns the current seek position from the start of the stream. Read more
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### impl Seek for File

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#### fn seek(&mut self, pos: SeekFrom) -> Result<u64>

Seek to an offset, in bytes, in a stream. Read more
1.55.0 · source§

#### fn rewind(&mut self) -> Result<()>

Rewind to the beginning of a stream. Read more
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#### fn stream_len(&mut self) -> Result<u64>

🔬This is a nightly-only experimental API. (`seek_stream_len` #59359)
Returns the length of this stream (in bytes). Read more
1.51.0 · source§

#### fn stream_position(&mut self) -> Result<u64>

Returns the current seek position from the start of the stream. Read more
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### impl Write for &File

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#### fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written. Read more
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#### fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like `write`, except that it writes from a slice of buffers. Read more
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#### fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Write`r has an efficient `write_vectored` implementation. Read more
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#### fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
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#### fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer. Read more
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#### fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬This is a nightly-only experimental API. (`write_all_vectored` #70436)
Attempts to write multiple buffers into this writer. Read more
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#### fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered. Read more
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#### fn by_ref(&mut self) -> &mut Self where Self: Sized,

Creates a “by reference” adapter for this instance of `Write`. Read more
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### impl Write for File

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#### fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written. Read more
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#### fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like `write`, except that it writes from a slice of buffers. Read more
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#### fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (`can_vector` #69941)
Determines if this `Write`r has an efficient `write_vectored` implementation. Read more
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#### fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more
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#### fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer. Read more
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#### fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬This is a nightly-only experimental API. (`write_all_vectored` #70436)
Attempts to write multiple buffers into this writer. Read more
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#### fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered. Read more
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#### fn by_ref(&mut self) -> &mut Self where Self: Sized,

Creates a “by reference” adapter for this instance of `Write`. Read more

## Auto Trait Implementations§

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### impl RefUnwindSafe for File

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### impl Send for File

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### impl Sync for File

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### impl Unpin for File

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### impl UnwindSafe for File

## Blanket Implementations§

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### impl<T> Any for Twhere T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for Twhere T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for Twhere T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for Twhere U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for Twhere U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.