[root@tmp:~]# uname -a
Linux tmp 5.10.93 #1-NixOS SMP Thu Jan 20 08:17:52 UTC 2022 x86_64 GNU/Linux

[root@tmp:~]# nix build github:mic92/cntr/k3s
trace: Warning: `stdenv.lib` is deprecated and will be removed in the next release. Please use `lib` instead. For more information see https://github.com/NixOS/nixpkgs/issues/108938

[root@tmp:~]# result/bin/cntr attach $(pgrep nginx)
failed to apply capabilities, failed to read capability limit, failed to open /proc/sys/kernel/cap_last_cap, No such file or directory (os error 2)
<hangs here until interrupted>