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Added example of using 3rd party fish plugins on plain NixOS
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→Setting fish as default shell: remove {{expansion}} as i've implemented the changes. If this change has broken something for you, please discuss at Talk:Fish#Suggested_bashrc_in_Fish#Setting_fish_as_default_shell_needs_revision
 
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{{DISPLAYTITLE:fish}}
{{DISPLAYTITLE:fish}}
fish, the [http://fishshell.com/ Friendly Interactive Shell], is a [[Command Shell|command shell]] designed around user-friendliness.
fish, the [https://fishshell.com/ Friendly Interactive Shell], is a [[Command Shell|command shell]] designed around user-friendliness.


== Installation ==
== Installation ==
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Replace <code>myuser</code> with the appropriate username.
Replace <code>myuser</code> with the appropriate username.


{{warning| [https://fishshell.com/docs/current/index.html#default-shell As noted in the fish documentation], using fish as your *login* shell (via <code>/etc/passwd</code>) may cause issues, particularly for the <code>root</code> user, because fish is not POSIX compliant. While using fish as the default shell for regular users is generaly safe, caution is still advised. See the [[#section Setting fish as default shell|Setting fish as default shell]] section for recommendations and mitigations.}}
{{warning| [https://fishshell.com/docs/current/index.html#default-shell As noted in the fish documentation], using fish as your *login* shell (via <code>/etc/passwd</code>) may cause issues, particularly for the <code>root</code> user, because fish is not POSIX compliant. While using fish as the default shell for regular users is generaly safe, caution is still advised. See [[#Setting fish as default shell]] for recommendations and mitigations.}}


=== Home Manager ===
=== Home Manager ===
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     grc
     grc
     # Use 3rd-party fish plugins manually packaged.
     # Use 3rd-party fish plugins manually packaged.
     pkgs.callPackage ../fish-colored-man.nix {buildFishPlugin = pkgs.fishPlugins.buildFishPlugin; } )
     (pkgs.callPackage ../fish-colored-man.nix {buildFishPlugin = pkgs.fishPlugins.buildFishPlugin; } )
   ];
   ];
</nowiki>
</nowiki>
}}
|name=/etc/nixos/configuration.nix|lang=nix}}
Example of a file containing the definition of a fish plugin.
Example of a file containing the definition of a fish plugin.
{{file|/etc/nixos/fish-colored-man.nix|nix|
{{file|/etc/nixos/fish-colored-man.nix|nix|
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=== Setting fish as default shell ===
=== Setting fish as default shell ===


Using fish as the the login shell can cause compatibility issues. For example, certain recovery environments such as systemd's emergency mode to be completely broken when fish was set as the login shell. This  limitation is noted on the [https://wiki.gentoo.org/wiki/Fish#Caveats Gentoo] wiki. There they present an alternative, keeping bash as the system shell but having it exec fish when run interactively.
Using fish as the the login shell can cause compatibility issues. For example, certain recovery environments such as systemd's emergency mode to be completely broken when fish was set as the login shell. ArchWiki presents an [https://wiki.archlinux.org/title/Fish#Modify_.bashrc_to_drop_into_fish alternative solution], keeping bash as the system shell but having it exec fish when run interactively.


Here is one solution, which launches fish unless the parent process is already fish:
Here is one solution, which launches fish unless the parent process is already fish:
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programs.bash = {
programs.bash = {
   interactiveShellInit = ''
   interactiveShellInit = ''
     if [[ $(${pkgs.procps}/bin/ps --no-header --pid=$PPID --format=comm) != "fish" && -z ''${BASH_EXECUTION_STRING} ]]
    # "check if parent process is not fish" && "make nested shells work properly"
    then
     if grep -qv fish /proc/$PPID/comm && [[ $SHLVL == [12] ]]; then
      shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=""
        # set $SHELL for better integration with programs like nix shell, tmux, etc.
      exec ${pkgs.fish}/bin/fish $LOGIN_OPTION
        SHELL=${pkgs.fish}/bin/fish exec fish
     fi
     fi
   '';
   '';
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</nowiki>
</nowiki>
}}
}}
For a more detailed explanation, please see the [https://wiki.archlinux.org/title/Fish#Modify_.bashrc_to_drop_into_fish aforementioned ArchWiki page].
'''Setting fish as default for Gnome Console'''
It is possible to set fish as the interactive non-login shell for Gnome Console without setting fish as the login shell (the login shell in /etc/passwd for your user will not be fish).
{{File|3=home-manager.users.myuser = {
    dconf = {
        enable = true;
        settings."org/gnome/Console" = {
            shell = [ "fish" ];
        };
    };
};|name=home.nix|lang=nix}}


If you still want to set fish as the login shell, see [[Command Shell#Changing the default shell]].
If you still want to set fish as the login shell, see [[Command Shell#Changing the default shell]].
==== Disable man page generation ====
Some users suffer from slow build due to fish enabling `documentation.man.generateCaches`. You may force false.
documentation.man.generateCaches = false'';''
For home-manager users, man cache need to be disabled in programs
programs.man.generateCaches = false'';''


==== Running fish interactively with zsh as system shell on darwin ====
==== Running fish interactively with zsh as system shell on darwin ====
{{outdated|date=May 14, 2026|reason=I've updated the interactiveShellInit snippet that this section refers to. Either the following paragraph should be reworded or the provided zsh config be modified. For more context, please see my corresponding [https://wiki.nixos.org/w/index.php?title=Fish&oldid=31760 edit] and the linked talk page.|talk=Talk:Fish#Suggested_bashrc_in_Fish#Setting_fish_as_default_shell_needs_revision}}


Zsh users on darwin will need to use a modified version of the above snippet. As written, it presents two incompatibilities. First, being BSD-derived, MacOS's <code>ps</code> command accepts different options. Second, this is a script intended for bash, not zsh. MacOS uses zsh as its default shell.
Zsh users on darwin will need to use a modified version of the above snippet. As written, it presents two incompatibilities. First, being BSD-derived, MacOS's <code>ps</code> command accepts different options. Second, this is a script intended for bash, not zsh. MacOS uses zsh as its default shell.
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)
)
</syntaxhighlight>
</syntaxhighlight>
{{Note|This won't work with the new {{ic|nix shell}} command, as it doesn't set {{ic|IN_NIX_SHELL}} variable. You can instead check if {{ic|$SHLVL}} is {{ic|> 1}}, or check if {{ic|$PATH}} contains paths from {{ic|/nix/store}} (which get added at the beginning of the {{ic|$PATH}} when you enter nix shell). See https://github.com/NixOS/nix/issues/6677 for more context and workarounds.}}


and <code>$nix_shell_info</code> to the echo in that function, e.g.:
and <code>$nix_shell_info</code> to the echo in that function, e.g.:
Retrieved from "https://wiki.nixos.org/wiki/Fish"