I recently downloaded and unpacked the Rust Language from [this site](https://www.rust-lang.org/downloads.html) (Linux 64-bit). 

I then installed Rust using the given script in the download `install.sh`:

```none
root@kali:~# /root/rust-1.9.0-x86_64-unknown-linux-gnu/install.sh
install: uninstalling component 'rustc'
install: creating uninstall script at /usr/local/lib/rustlib/uninstall.sh
install: installing component 'rustc'
install: installing component 'rust-std-x86_64-unknown-linux-gnu'
install: installing component 'rust-docs'
install: installing component 'cargo'

    Rust is ready to roll.

```

I am trying to install a crate with cargo, but I keep running into this error:

```none
root@kali:~# cargo install racer
    Updating registry `https://github.com/rust-lang/crates.io-index`
   Compiling winapi v0.2.7
   Compiling bitflags v0.5.0
error: can't find crate for `std` [E0463]
error: aborting due to previous error
Build failed, waiting for other jobs to finish...
error: can't find crate for `std` [E0463]
error: aborting due to previous error
error: failed to compile `racer v1.2.10`, intermediate artifacts can be found at `/root/target-install`

```

`cargo install cargo-edit` failed with the same result as above, so it's not limited to one particular package.

Even putting a simple program:

```
fn main() {
    println!("Hello, world!");
}

```

in a file named `hello.rs` and running `rustc hello.rs` does not compile; it gives the same error: `error: can't find crate for 'std' [E0463]`.

The download came with a directory named `rust-std-x86_64-unknown-linux-gnu`, which I assume is the std crate. How do I instruct rustc to find this directory when trying to locate the std crate?