I want to run the following on ubunt 20.04:
sh <(curl -L https://nixos.org/nix/install) --daemon
what I got is this:
sh <(curl -L https://nixos.org/nix/install) --daemon
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100  4046  100  4046    0     0  16782      0 --:--:-- --:--:-- --:--:--   98k
downloading Nix 2.5.1 binary tarball for x86_64-linux from 'https://releases.nixos.org/nix/nix-2.5.1/nix-2.5.1-x86_64-linux.tar.xz' to '/tmp/nix-binary-tarball-unpack.KPhkYw21Nn'...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0Warning: Failed to create the file 
Warning: /tmp/nix-binary-tarball-unpack.KPhkYw21Nn/nix-2.5.1-x86_64-linux.tar.x
Warning: z: No such file or directory
  0 27.1M    0  1103    0     0  10753      0  0:44:05 --:--:--  0:44:05 10813
curl: (23) Failure writing output to destination
/dev/fd/63: failed to download 'https://releases.nixos.org/nix/nix-2.5.1/nix-2.5.1-x86_64-linux.tar.xz'
When I have a look at /dev/fd/ I see a bunch of files marked inaccessible:

I guess this has something to do with the failure to download. Am I right? What can I do against it? I am just a 'normal' ubuntu user, this kind of stuff exceeds my ubuntu-knowledge.
UPDATE:
Even if I run the whole thing as root the result remains the same:
