flk activate

Enter the Nix development shell for your project.

flk activate
flk activate --profile backend

Options

• -p, --profile <PROFILE>: Activate a specific profile instead of the default

Behavior

• Runs nix develop .#<profile> --impure to enter the dev shell
• Reuses a cached develop profile from .flk/.nix-profile-<profile> when your flake config is unchanged
• Refreshes that cached profile when flake.nix, flake.lock, or the relevant .flk profile files change
• Uses standard profile resolution when --profile is not specified
• Custom commands and environment variables from the profile are available inside the shell
• Exports FLK_FLAKE_REF/FLK_PROFILE into the shell so the hook’s refresh/switch commands know the active profile (flk global activate additionally exports FLK_ENV_DIR)
• Exports FLK_ORIG_PATH (the pre-activation PATH): refresh/switch reset to it so removed packages don’t linger in the inherited PATH

Shell selection

The shell exec’d inside the dev environment is resolved in this order:

1. FLK_SHELL environment variable (explicit override)
2. $SHELL, unless it points into /nix/store — nix develop/nix-shell export SHELL as nixpkgs’ non-interactive bash, which breaks interactive terminals (missing completion, broken prompt)
3. The login shell from /etc/passwd
4. /bin/sh

The refresh/switch hook functions apply the same logic.

Notes

• For automatic environment switching when navigating between projects, add the shell hook:

  eval "$(flk hook bash)"   # or zsh/fish
  

• For automatic activation when entering a directory, use direnv integration

See Also

• flk hook — for refresh and switch commands
• flk direnv — for automatic directory-based activation