The command substitution $(getent group render | cut -d: -f3) can produce an empty string if the render group does not exist on the host, causing the docker run command to fail with a confusing error. Since this logic is duplicated in the else block, it's best to perform the check once before the if/else block, store the GID in a variable, and reuse it.

This improves robustness, provides clearer error messages, and avoids code duplication. For example:

# Before the if-else block
render_gid=$(getent group render | cut -d: -f3)
if [[ -z "$render_gid" ]]; then
  echo "Error: 'render' group not found. This is required for GPU access." >&2
  exit 1
fi

# ... then inside both docker run commands:
--group-add "$render_gid" \

This duplicates the logic for getting the render group GID. As suggested in my other comment, this should be done once before the if/else block to improve robustness and avoid duplication.