Command Shell

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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, eg fish.


Always enable the shell system-wide, even if it's already enabled in your home.nix. Otherwise it wont source the necessary files.

programs.zsh.enable = true;

Changing default shell

Shells can be changed system-wide and per-user. To change the shell system-wide, add the following line to your config:

users.defaultUserShell = pkgs.zsh;

then run nixos-rebuild switch and reboot your system.

To only change the default shell for one of the users, add

/etc/nixos/configuration.nix = pkgs.zsh;

Many programs look at /etc/shells to determine if a user is a "normal" user and not a "system" user. Therefore it is recommended to add the user shells to this list. To add a shell to /etc/shells use the following line in your config:

environment.shells = with pkgs; [ zsh ];

Changing /bin/sh

Warning: Please note that NixOS assumes all over the place that shell is Bash, so override the default setting only if you know exactly what you're doing.

/bin/sh is a symlink to your default POSIX-Compliant shell. It's used when writing shell scripts, so that the script works on all machines independently of what shell the user is using. /bin/sh doesn't have to be the same as your interactive shell (e.g. the one you use in your terminal). In fact, a lot of people set their interactive shells to zsh/fish, but set /bin/sh to dash, because it's fast and scripts don't need any of those fancy zsh/fish features.

To change your default POSIX shell on NixOS, use

# Dash is just an example, you can use whatever you want
environment.binsh = "${pkgs.dash}/bin/dash";

See also