Command Shell: Difference between revisions

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-A shell is a program that translates text commands (like {{ic|ls}}, {{ic|vim}}, {{ic|reboot}} etc) into instructions for your computer. The default shell on NixOS is [[bash]], but it can be easily changed.
+A [https://en.wikipedia.org/wiki/Unix_shell shell] is a program that translates text commands (like {{ic|ls}}, {{ic|vim}}, {{ic|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]]:
+{{file|/etc/nixos/configuration.nix|nix|<nowiki>
+programs.zsh.enable = true;
+</nowiki>}}
+== Changing the default shell ==
+=== For all users ===
+To set a command shell as the default for all users, use the [https://search.nixos.org/options?query=defaultUserShell <code>defaultUserShell</code>] option.
+For example, to set Zsh as the default user shell for all users(including root):
-== 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:
-{{note|[[Zsh]] is used here as an example. You can use other shells, eg {{ic|pkgs.fish}}.}}
 {{file|/etc/nixos/configuration.nix|nix|<nowiki>
 users.defaultUserShell = pkgs.zsh;
 </nowiki>}}
-then run {{ic|nixos-rebuild switch}} and reboot your system.
-To only change the default shell for one of the users, add
+=== For a specific user ===
+To set a command shell as the default for a particular user, use the [https://search.nixos.org/options?query=%3Cname%3E.shell <code><nowiki><name></nowiki>.shell</code>] option.
+For example, to set user "myuser"'s shell to [[fish]]:
 {{file|/etc/nixos/configuration.nix|nix|<nowiki>
-shell = pkgs.zsh;
+users.users.myuser.shell = pkgs.fish;
 </nowiki>}}
-to your user's section like so:
+You can also choose whether or not a user should use the default shell:
 {{file|/etc/nixos/configuration.nix|nix|<nowiki>
-users.users.yourname = {}
+users.users.myuser.useDefaultShell = true;
-  ... # Your user configuration
-  shell = pkgs.zsh;
-};
 </nowiki>}}
+== Using a different shell in nix-shell and nix develop ==
+By default, both <code>nix develop</code> and <code>nix-shell</code> 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 [https://github.com/MercuryTechnologies/nix-your-shell nix-your-shell] for installation and usage instructions.
+=== any-nix-shell ===
+Refer to [https://github.com/haslersn/any-nix-shell 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:
+{{file|.bashrc|bash|
+<nowiki>
+alias nix-shell='nix-shell --run zsh'
+nix() {
+  if [[ $1 == "develop" ]]; then
+    shift
+    command nix develop -c zsh "$@"
+  else
+    command nix "$@"
+  fi
+}
+</nowiki>
+}}
+There are some caveats with this approach:
+* Nested shells will require you to type <code>exit</code> 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.
+== Using Flakes ==
+If you are using [[Flakes]] with fish, the 'command-not-found' error message will not work correctly, but can be fixed by disabling the builtin Nix <code>command-not-found</code> program:<ref>https://github.com/NixOS/nixpkgs/issues/425613#issuecomment-3076081921</ref>
+{{File|3=programs.command-not-found.enable = false;|name=/etc/nixos/configuration.nix|lang=nix}}
 == See also ==
+* [[Fish]]
+* [[Nushell]]
 * [[Zsh]]
+* [[Flakes]]
+[[Category:Configuration]]
+[[Category:Software]]
+[[Category:Shell]]