$ cat /etc/upstream-release/lsb-release
cat: /etc/upstream-release/lsb-release: No such file or directory

$ cat /etc/os-release
BUG_REPORT_URL="https://github.com/NixOS/nixpkgs/issues"
BUILD_ID="23.11pre504832.8acef304efe"
DOCUMENTATION_URL="https://nixos.org/learn.html"
HOME_URL="https://nixos.org/"
ID=nixos
LOGO="nix-snowflake"
NAME=NixOS
PRETTY_NAME="NixOS 23.11 (Tapir)"
SUPPORT_URL="https://nixos.org/community.html"
VERSION="23.11 (Tapir)"
VERSION_CODENAME=tapir
VERSION_ID="23.11"


$ cat /usr/lib/os-release
cat: /usr/lib/os-release: No such file or directory

$ cat /etc/lsb-release
DISTRIB_CODENAME=tapir
DISTRIB_DESCRIPTION="NixOS 23.11 (Tapir)"
DISTRIB_ID=nixos
DISTRIB_RELEASE="23.11"
LSB_VERSION="23.11 (Tapir)"