Command Shell

A shell is a program that translates text commands (like ls, vim, reboot etc) into instructions for your computer. The default shell on NixOS is bash, but it can be easily changed.

Note: Zsh is used here as an example. You can use other shells, e.g. fish or nushell.

Enable

When adding a new shell, always enable the shell system-wide, even if it's already enabled in your Home Manager configuration, otherwise it won't source the necessary files.

For example, for Zsh:

❄︎ /etc/nixos/configuration.nix

programs.zsh.enable = true;

Changing the default shell

For all users

To set a command shell as the default for all users, use the defaultUserShell option.

For example, to set Zsh as the default user shell for all users(including root):

❄︎ /etc/nixos/configuration.nix

users.defaultUserShell = pkgs.zsh;

For a specific user

To set a command shell as the default for a particular user, use the <name>.shell option.

For example, to set user "myuser"'s shell to fish:

❄︎ /etc/nixos/configuration.nix

users.users.myuser.shell = pkgs.fish;

You can also choose whether or not a user should use the default shell:

❄︎ /etc/nixos/configuration.nix

users.users.myuser.useDefaultShell = true;

Using a different shell in nix-shell and nix develop

By default, both nix develop and nix-shell launch an interactive bash shell. However, it is possible to configure these environments to use an alternative shell.

There are multiple approaches available:

nix-your-shell

Refer to nix-your-shell for installation and usage instructions.

any-nix-shell

Refer to any-nix-shell for installation and usage instructions.

Aliasing command

A simple, lightweight method is to alias the relevant commands to invoke the shell directly. For example:

≡︎ .bashrc

alias nix-shell='nix-shell --run zsh'
nix() {
  if [[ $1 == "develop" ]]; then
    shift
    command nix develop -c zsh "$@"
  else
    command nix "$@"
  fi
}

There are some caveats with this approach:

• Nested shells will require you to type exit twice, once to leave the inner shell and once to exit the Nix shell environment itself.
• Potential for alias conflicts as overriding commands can introduce unintended side effects in scripts or other tooling that expects the standard behavior.

See also

• Fish
• Nushell
• Zsh