# shell-download
| `shell-download` | [](https://docs.rs/shell-download) | [](https://crates.io/crates/shell-download) |
A zero-dependency Rust library for downloading a URL to a file by delegating to
whatever download tools are available on the current system.
It hunts for (in order): `curl`, `wget`, `pwsh`/`powershell`, `python3`, then the
built-in **tunnel** (HTTP over TCP, HTTPS via OpenSSL / `openssl s_client`). You can still
force only the TCP or only the OpenSSL stack with [`Downloader::Tcp`] and
[`Downloader::OpenSSL`].
- The caller provides a target path.
- That file is unlinked before the request starts.
- The response body is written to that path (decompressed if the response is gzip).
- The request runs in a background thread and returns a cancellable handle.
## When to use this crate
If you can afford the compile-time cost and binary size of a much
fuller-featured crate such as `reqwest`, that's probably a better choice. But if
you need a small, zero-dependency library for just downloading a file, and you'd
prefer not to add code to call into `curl` or `wget` or `pwsh` or whatever
happens to be installed on a random machine, this crate is a good choice.
## Features
By default, these features are not enabled, making the crate zero-dependency.
- `url`: Parse URLs using the `url` crate (adds a number of dependencies, but
makes URL parsing more accurate).
## Usage
```rust
use shell_download::{Downloader, RequestBuilder};
fn main() -> Result<(), shell_download::ResponseError> {
// NOTE: This should use a secure temporary file name!
let out = std::env::temp_dir().join("downloaded.json");
let handle = RequestBuilder::new("https://httpbin.org/redirect/5")
.header("User-Agent", "shell-download/0.1")
.follow_redirects(true)
// Optional: force a specific backend (useful for tests)
.preferred_downloader(Downloader::Curl)
.start(&out)
.map_err(shell_download::ResponseError::Start)?;
// Optional: cancel from another thread if you need to abort
// handle.cancel();
let response = handle.join()?;
println!("status={}", response.status_code);
let body = std::fs::read_to_string(out).unwrap();
assert!(body.contains("httpbin.org/get"));
Ok(())
}
```