Reference · Files and processes

delete_file

delete_file(str) -> null | error(str)

What it does

Removes a file under the program's folder, or a folder and everything in it. It gives null when the path is gone, also when there was nothing there, and an error value when the path leaves the folder or names the folder itself.

Examples

write_file("tmp/a.txt", "a")print(delete_file("tmp/a.txt"))print(read_file("tmp/a.txt") ?? "gone")

nullgone

Edge cases

• Deleting what is not there is null, not an error: a second delete is harmless.
• A folder is removed with everything in it.
• ".", "", ".." and a path starting at / are error values: the program's own folder is never removed, and nothing outside it is touched.
• The program's own files are refused as write_file refuses them (its .qwe files, .env, the databases it has open, in any case and as Windows reads a name), and so is a folder that holds one: delete_file("data") with data/app.db open is an error value, and nothing is deleted.
• Links are followed, and where they lead is what counts: a link inside the folder that leads inside it works as its target would, and one that leads out of the folder, or leads nowhere, is an error value, and nothing is deleted: a path is judged where it leads, so delete_file("data") on a link out of the folder is refused too. The first such path is said once in the log, with where it leads and --allow-path FOLDER, the option of quillo run that lets the program reach a folder outside on purpose (quillo run main.qwe --allow-path /srv/media; see the options).

print(delete_file("nope.txt"), delete_file("nope.txt"))write_file("tmp/a/b.txt", "b")write_file("tmp/c.txt", "c")print(delete_file("tmp"), read_file("tmp/c.txt") ?? "gone")print(delete_file("."), delete_file(""))print(delete_file("../x"), delete_file("/tmp/x"))

null nullnull goneerr("delete_file: path must be inside the program's folder: .") err("delete_file: path must be inside the program's folder: ")err("delete_file: path must be inside the program's folder: ../x") err("delete_file: path must be inside the program's folder: /tmp/x")

Errors

A path outside the folder, or one of the program's own files or a folder holding one, is an error value, which ? passes on; a path that is not a string is a runtime error.

let r = delete_file("..")print(is_err(r), r.error)

true delete_file: path must be inside the program's folder: ..

db.open("app.db")print(delete_file("app.db"), delete_file("MAIN.qwe"))

err("delete_file: will not delete app.db: it is the database the program has open") err("delete_file: will not delete MAIN.qwe: it is one of the program's own files")

print(delete_file(1))

line 1: `delete_file` expects a str as argument 1, got int

Chaining

write_file("a.txt", "a")write_file("b.txt", "b")print(["a.txt", "b.txt"] | map(delete_file))print("a.txt" | read_file ?? "gone")

[null, null]gone

See also

write_file, read_file, save_upload

Edit this page on GitHub · every example's output was made by running it (tools/refcheck.mjs) · questions on Discord or r/quillo