Attempts to open a file in read-only mode.

See the OpenOptions::open method for more details.

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;

let mut f = File::open("foo.txt")?;

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.

See the OpenOptions::open function for more details.

Examples

use std::fs::File;

let mut f = File::create("foo.txt")?;

Attempts to sync all OS-internal metadata to disk.

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

Examples

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

let mut f = File::create("foo.txt")?;
f.write_all(b"Hello, world!")?;

f.sync_all()?;

This function is similar to sync_all, except that it may 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::*;

let mut f = File::create("foo.txt")?;
f.write_all(b"Hello, world!")?;

f.sync_data()?;

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.

Errors

This function will return an error if the file is not opened for writing.

Examples

use std::fs::File;

let mut f = File::create("foo.txt")?;
f.set_len(10)?;

Queries metadata about the underlying file.

Examples

use std::fs::File;

let mut f = File::open("foo.txt")?;
let metadata = f.metadata()?;

Creates a new independently owned handle to the underlying file.

The returned File is a reference to the same state that this object references. Both handles will read and write with the same cursor position.

Examples

use std::fs::File;

let mut f = File::open("foo.txt")?;
let file_copy = f.try_clone()?;

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

use std::fs::File;

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

Formats the value using the given formatter.

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read the exact number of bytes required to fill buf. Read more

Creates a "by reference" adaptor for this instance of Read. Read more

Transforms this Read instance to an Iterator over its bytes. Read more

Transforms this Read instance to an Iterator over chars. Read more

Creates an adaptor which will chain this stream with another. Read more

Creates an adaptor which will read at most limit bytes from it. Read more

Write a buffer into this object, returning how many bytes were written. Read more

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

Attempts to write an entire buffer into this write. Read more

Writes a formatted string into this writer, returning any error encountered. Read more

Creates a "by reference" adaptor for this instance of Write. Read more

Seek to an offset, in bytes, in a stream. Read more

Pull some bytes from this source into the specified buffer, returning how many bytes were read. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read all bytes until EOF in this source, placing them into buf. Read more

Read the exact number of bytes required to fill buf. Read more

Creates a "by reference" adaptor for this instance of Read. Read more

Transforms this Read instance to an Iterator over its bytes. Read more

Transforms this Read instance to an Iterator over chars. Read more

Creates an adaptor which will chain this stream with another. Read more

Creates an adaptor which will read at most limit bytes from it. Read more

Write a buffer into this object, returning how many bytes were written. Read more

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

Attempts to write an entire buffer into this write. Read more

Writes a formatted string into this writer, returning any error encountered. Read more

Creates a "by reference" adaptor for this instance of Write. Read more

Seek to an offset, in bytes, in a stream. Read more

Extracts the raw file descriptor. Read more

Constructs a new instance of Self from the given raw file descriptor. Read more

Consumes this object, returning the raw underlying file descriptor. Read more

Reads a number of bytes starting from a given offset. Read more

Writes a number of bytes starting from a given offset. Read more