Install latest asdf stable and asdf-direnv, from scratch, and make it all work

asdf-direnv.sh

#!/bin/sh
shell=$(basename $SHELL)

# Exit if we don't support your shell
if [ $shell != "zsh" -a $shell != "bash" ]; then
  printf "This script only works if you're using zsh or bash\n"
  exit 1
fi

# Crash if the asdf or direnv commands already exist, or if ~/.asdf, ~/.envrc or ~/.tool-versions already exist
if [ \
  "$(command -v asdf)" -o \
  "$(command -v direnv)" -o \
  -e $HOME/.asdf -o \
  -e $HOME/.envrc -o \
  -e $HOME/.tool-versions \
]; then
  printf "This script assumes asdf and direnv are not already installed. Please make sure this is the case, and remove .asdf, .envrc and .tool-versions from your home directory if you want to use this script.\n"
  exit 1
fi

printf "\
This command will do the following:
  - Replace/remove custom asdf and direnv configuration you may have in $HOME/.config
  - Install asdf in $HOME/.asdf
  - Install the direnv plugin and set up asdf-direnv which installs the latest version of direnv in asdf
  - Make direnv available everywhere by adding it to your global tools in $HOME/.tool-versions
  - Write 4 lines (including a comment) to the bottom of your $HOME/.${shell}rc that do the following:
    - Add the asdf binary to your \$PATH
    - Hook direnv in your shell
    - Silence direnv's logging

To uninstall, remove $HOME/.asdf, $HOME/.envrc and $HOME/.tool-versions, and remove the 4 lines from your $HOME/.${shell}rc

"

# Abort unless the user's answer begins with Y or y
read -p "Do you want to continue? [y/N] " -n 1 -r
printf "\n"
if ! [[ $REPLY =~ ^[Yy]$ ]]; then
  printf "Aborting.\n"
  exit 1
fi

cd
printf "\n*****\n* Installing asdf\n*****\n\n"

# Install asdf from git and update to latest stable tag.
git clone -q https://github.com/asdf-vm/asdf.git .asdf
.asdf/bin/asdf update 2>/dev/null

# Don't load it in rc (direnv will take care of that). Instead, add it to $PATH.
printf '\n# asdf-direnv: add asdf to your path and hook direnv into your shell\n' >> $HOME/.${shell}rc
printf 'export PATH="$HOME/.asdf/bin:$PATH"\n' >> $HOME/.${shell}rc

printf "\n*****\n* Installing direnv\n*****\n\n"

# Hook asdf into our current session, we do need it to get direnv up and running
source .asdf/asdf.sh

# Install the direnv plugin and setup asdf-direnv
asdf plugin add direnv
asdf direnv setup --version latest
printf 'export DIRENV_LOG_FORMAT=""\n' >> $HOME/.${shell}rc

# Make sure we can use direnv everywhere by creating a .tool-versions and creating and allowing a .envrc file
asdf direnv local direnv latest

printf "\n*****\n* All done. Please exit and start a new ${shell} session for it to work. \n*****\n\n"