direnv fetchurl - Fetch a URL to disk
direnv fetchurl 
This command downloads the given URL into a fixed disk location, based on the content of the retrieved file.
This has been introduced to avoid a dependency on
wget, while also
promoting a more secure way to fetch data from the Internet. Use this instead
curl <url> | sh.
This command has two modes of operation:
Since the on-disk location is based on the hash, it also acts as a cache. One implication of this design is that URLs must be stable and always return the same content.
Downloaded files are marked as read-only and executable so it can also be used to fetch and execute static binaries.
direnv fetchurl outputs different content based on the argument.
integrity-hash is being passed, it will output the path to the
on-disk location, if the retrieval was successful.
If only the
url is being passed, it will output the hash as well as some
human-readable instruction. If stdout is not a tty, only the hash will be
$ ./direnv fetchurl https://releases.nixos.org/nix/nix-2.3.7/install Found hash: sha256-7Gxl5GzI9juc/U30Igh/pY+p6+gj5Waohfwql3jHIds= Invoke fetchurl again with the hash as an argument to get the disk location: direnv fetchurl "https://releases.nixos.org/nix/nix-2.3.7/install" "sha256-7Gxl5GzI9juc/U30Igh/pY+p6+gj5Waohfwql3jHIds=" #=> /home/zimbatm/.cache/direnv/cas/sha256-7Gxl5GzI9juc_U30Igh_pY+p6+gj5Waohfwql3jHIds=
This variable is used to select the on-disk location of the fetched URLs
$XDG_CACHE_HOME/direnv/cas. If XDG_CACHE_HOME is unset or empty,
MIT licence - Copyright (C) 2019 @zimbatm and contributors