File system functions

The std::fs module provides multiple functions to interact with the file system. See Table 1.

Table 1:Some functions of the std::fs module

Function	Description
`copy(p, q)`	Copies the content of file `p` into `q`.
`create_dir(p)`	Creates a new folder.
`create_dir_all(p)`	Creates a new folder and all its parents if necessary.
`hard_link(p, q)`	Creates a new hard link `q` for `p`.
`read(p)`	Reads the whole content of a file into a byte vector `Vec<u8>`.
`read_to_string(p)`	Reads the whole content of a file into a `String`.
`remove_dir(p)`	Deletes an empty folder.
`remove_dir_all(p)`	Deletes a folder and all its content.
`remove_file(p)`	Deletes a file.
`rename(p, q)`	Renames a file or folder, overwriting any existing file at `q`.
`set_permissions(p, perm)`	Changes permissions of a file or directory.
`set_times(p, times)`	Changes the timestamps of a file or directory.
`write(p, s)`	Writes the content of `s` into the file at `p`. The file is created if it does not exist, and overwritten otherwise. `s` can be a regular string slice or a byte slice.

:clear

let tmp_dir = std::env::temp_dir().join(format!("myst-rust-{}", std::process::id()));
std::fs::create_dir_all(&tmp_dir)?;
std::env::set_current_dir(&tmp_dir)?;

Couldn't automatically determine type of variable `tmp_dir`.
Please give it an explicit type.

36.3.1Writing a whole file¶

The write() function writes an entire string or byte string into a file:

let content = "abcdef";
let file = std::path::Path::new("foo.txt");
std::fs::write(file, content)?;

36.3.2Reading a whole file¶

The read_to_string() function reads a whole text file into a String:

let content = std::fs::read_to_string(file)?;
content

36.3.3Getting the size of a file¶

To obtain the size of a file, we need first to access the file’s metadata and then call the len() method onto the Metadata object:

file.metadata()?.len()

Checking if a file is empty is thus as easy as:

file.metadata()?.len() == 0

36.3.4Checking path existence¶

The exists() method of the Path struct tests the existence of a path:

file.exists()

36.3.5Testing file or folder¶

To test if a path is a file or a folder we use the is_file() and is_dir() methods:

(file.is_file(), file.is_dir())

36.3.6Creating a folder¶

The create_dir() function creates a new folder, at the condition that the parent path exists:

std::fs::create_dir("my_folder")

The create_dir_all() function creates a new folder, with all missing parent folders:

std::fs::create_dir_all("my/other/folder")

36.3 File system functions

36.3.1Writing a whole file¶

36.3.2Reading a whole file¶

36.3.3Getting the size of a file¶

36.3.4Checking path existence¶

36.3.5Testing file or folder¶

36.3.6Creating a folder¶