Load a project variable with direnv

Set up a direnv shell hook, inspect and allow a small .envrc, and watch a project variable disappear when you leave.

how-to4 steps

Updated

in short

direnv loads environment changes from an allowed .envrc when you enter a directory and unloads them when you leave.

Use the small fixture below to check the workflow before applying it to your own project.

Tools used

Before you start

  • A Bash or Zsh terminal on Linux or macOS
  • The listed tools installed and available on PATH

Steps

  1. Step 1: Enable your shell hook

    For Bash, add this line once at the end of ~/.bashrc, then open a new terminal. For Zsh, use direnv hook zsh in ~/.zshrc instead.

    sh
    eval "$(direnv hook bash)"

  2. Step 2: Create and inspect the project file

    The variable is harmless. Read an .envrc before allowing it: it is executable shell code.

    sh
    trmn_guide_dir="$(mktemp -d)"
cd "$trmn_guide_dir"
printf '%s\n' 'export TRMN_GUIDE_COLOR=green' > .envrc
cat .envrc
    output
    export TRMN_GUIDE_COLOR=green

  3. Step 3: Allow and inspect it

    Run each line at a separate prompt so the hook can update your environment.

    sh
    direnv allow .
printf "%s\n" "$TRMN_GUIDE_COLOR"

  4. Step 4: Leave the project

    Again, wait for the next prompt before printing the variable.

    sh
    cd ..
printf "%s\n" "${TRMN_GUIDE_COLOR-unset}"

Further reading

[direnv shell hooks](https://direnv.net/docs/hook.html) · [direnv documentation](https://direnv.net/)

FAQ

Why is my variable still empty?
The shell hook updates the environment at prompt boundaries. Reopen your shell after installing the hook and execute the example one line at a time.
What happens when .envrc changes?
Review the changed file, then allow it again. Do not approve an unfamiliar file just to silence the warning.

related

direnv details