Add the following to your .bashrc
or wherever you keep this information. See https://asdf-vm.com/guide/getting-started.html#_3-install-asdf for details if you aren't using bash
ASDF_DIR="${HOME}/.asdf"
if ! [[ -d "$ASDF_DIR" ]]; then
git clone https://github.com/asdf-vm/asdf.git "$ASDF_DIR" --branch v0.11.3
fi
if [[ -d "$ASDF_DIR" ]]; then
. "${ASDF_DIR}/asdf.sh"
. "${ASDF_DIR}/completions/asdf.${shell}"