Read and change file metadata

Every file carries metadata besides its contents: size, timestamps, type and permissions. This example reads that metadata with Ende.stat, changes permissions with Ende.chmod, and sets timestamps with Ende.utime.

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We set up a temporary directory with a small file to inspect.

const dir = await Ende.makeTempDir();
const path = `${dir}/data.txt`;
await Ende.writeTextFile(path, "twelve bytes");

Ende.stat returns a FileInfo object with the size in bytes, the type and the timestamps. The timestamps are Date objects (or null on platforms that do not record them).

const info = await Ende.stat(path);
console.log(info.size); // 12
console.log(info.isFile); // true
console.log(info.mtime instanceof Date); // true
console.log(info.birthtime instanceof Date); // true

On a symlink, stat follows the link and describes the target, while lstat describes the link itself.

await Ende.symlink(path, `${dir}/link.txt`);
console.log((await Ende.stat(`${dir}/link.txt`)).isFile); // true
console.log((await Ende.lstat(`${dir}/link.txt`)).isSymlink); // true

The mode field holds the raw Unix permission bits. Masking with 0o777 keeps just the permission part, in the familiar octal form.

console.log((info.mode! & 0o777).toString(8)); // 644

Ende.chmod changes those permission bits. Here we drop access for group and others. On Windows only the write permission can be changed, and stat reports mode as null there.

await Ende.chmod(path, 0o600);
const after = await Ende.stat(path);
console.log((after.mode! & 0o777).toString(8)); // 600

Ende.utime sets the access and modification times to any date you like, which is handy for tools like build systems that compare timestamps.

const date = new Date("2020-01-02T03:04:05Z");
await Ende.utime(path, date, date);
console.log((await Ende.stat(path)).mtime?.toISOString()); // 2020-01-02T03:04:05.000Z

Reading metadata requires the -R permission; chmod and utime require -W.

await Ende.remove(dir, { recursive: true });

Run this example locally using the Ende CLI:

ende run -R -W https://docs.ende.sh/examples/scripts/file_metadata.ts

Read and change file metadata

Additional resources