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]].}}

~~{{note|[[Zsh]] is used here as an example. You can use other shells, eg {{ic|fish}}.}}~~

== Enable ==

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

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 default shell ==

== Changing the default shell ==

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

=== 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):

{{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>

users.users.~~yourname~~.shell = pkgs.~~zsh~~;

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

</nowiki>}}

~~== Changing /bin/sh ==~~

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

~~{{Warning|Please note that NixOS assumes all over the place that shell to be Bash, so override the default setting only if you know exactly what you're doing.}}~~

~~{{ic|/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

{{file|/etc/nixos/configuration.nix|nix|<nowiki>

<~~syntaxhighlight lang~~="nix">

users.users.myuser.useDefaultShell = true;

~~# Dash is just an example~~, ~~you~~ can ~~use whatever you want~~

</nowiki>}}

~~environment.binsh~~ = ~~"${pkgs~~.~~dash}~~/~~bin~~/~~dash";~~

</~~syntaxhighlight~~>

== 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|

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]]

* [[~~Fish~~]]

* [[Flakes]]

[[Category:Configuration]]

[[Category:Software]]

[[Category:Shell]]

@@ Line 1: / Line 1: @@
-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]].}}
-{{note|[[Zsh]] is used here as an example. You can use other shells, eg {{ic|fish}}.}}
 == Enable ==
-Always enable the shell system-wide, even if it's already enabled in your <code>home.nix</code>. Otherwise it wont source the necessary files.
+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 default shell ==
+== Changing the default shell ==
-Shells can be changed system-wide and per-user. To change the shell system-wide, add the following line to your config:
+=== 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):
 {{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>
-users.users.yourname.shell = pkgs.zsh;
+users.users.myuser.shell = pkgs.fish;
 </nowiki>}}
-== Changing /bin/sh ==
+You can also choose whether or not a user should use the default shell:
-{{Warning|Please note that NixOS assumes all over the place that shell to be Bash, so override the default setting only if you know exactly what you're doing.}}
-{{ic|/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
+{{file|/etc/nixos/configuration.nix|nix|<nowiki>
-<syntaxhighlight lang="nix">
+users.users.myuser.useDefaultShell = true;
-# Dash is just an example, you can use whatever you want
+</nowiki>}}
-environment.binsh = "${pkgs.dash}/bin/dash";
-</syntaxhighlight>
+== 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]]
-* [[Fish]]
+* [[Flakes]]
 [[Category:Configuration]]
 [[Category:Software]]
+[[Category:Shell]]