I am trying to install the NVIDIA Container Toolkit. The command to set up the repository and specify the GPG key is:

distribution=$(. /etc/os-release;echo $ID$VERSION_ID) \
      && curl -fsSL  | sudo gpg --dearmor -o /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg \
      && curl -s -L  | \
            sed 's#deb  [signed-by=/usr/share/keyrings/nvidia-container-toolkit-keyring.gpg]  | \
            sudo tee /etc/apt/sources.list.d/nvidia-container-toolkit.list

However, I do not have an /etc/os-release file. I expect that /etc/os-release is meant to provide information about my operating system (i.e. Ubuntu 20.04). I do have two files, which appear to have similar intent, but are not executable: /usr/lib/os-release and /etc/debian file.

The contents of /usr/lib/os-release are:

$ cat /usr/lib/os-release
NAME="Ubuntu"
VERSION="20.04.4 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.4 LTS"
VERSION_ID="20.04"
HOME_URL=""
SUPPORT_URL=""
BUG_REPORT_URL=""
PRIVACY_POLICY_URL=""
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

The contents of /etc/debian_version are:

$ cat /etc/debian_version 
bullseye/sid

Finally, if I execute lsb_release -a, I get:

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 20.04.4 LTS
Release:    20.04
Codename:   focal

So, with what do I need to replace

distribution=$(. /etc/os-release;echo $ID$VERSION_ID)