Difference between revisions of "Fish"

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(Updated to reflect my experiences with fish 3.4.0)
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See the [[Terminal_emulator#General_usage|terminal emulator]] article for some general usage pointers.
 
See the [[Terminal_emulator#General_usage|terminal emulator]] article for some general usage pointers.
  
−
{{Important|{{c|fish}} is not a POSIX compatible shell, it will cause issues if set as a user's login shell. See [[Fish#Caveats|caveats section]] for how to use {{c|fish}} as a user's default shell.}}
+
{{Important|See [[Fish#Caveats|caveats section]] for how to use {{c|fish}} as a user's default shell.}}
 +
 
 +
{{Warning|{{c|fish}} is not suitable for linking to {{c|/bin/sh}}, See the {{c|[[eselect]] sh}} utility for managing POSIX shells }}
  
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{{Warning|{{c|fish}} should not be set as the system shell by linking in /bin/sh. The {{c|[[eselect]] sh}} utility should not include a {{c|fish}} option.}}
 
  
 
== Installation ==
 
== Installation ==
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{{Emerge|app-shells/fish}}
 
{{Emerge|app-shells/fish}}
  
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== Caveats ==
+
== Configuration ==
 +
 
 +
The command {{c|fish_config}} can manage settings on in the shell or a web browser. To use a web browser you also need a $BROWSER env var, an example of setting this would be {{c|set -gx BROWSER /usr/bin/librewolf}} run in the shell, added to the user or system as below, or in the usual bash format in /etc/env.d if you follow the steps in 'Fish as a default shell'
 +
 
 +
The main files for configuration are {{Path|/etc/fish/config.fish}}, which is called by every shell, and the user init file {{Path|~/.config/fish/config.fish}} which does not exist by default. If the user file exists the system file is still used automatically.
 +
 
 +
Both {{Path|config/fish}} and {{Path|/etc/fish}} can contain a {{PATH|conf.d}} directory, this is handled slightly differently in that named files in the user's conf.d will prevent a file of the same name being sourced from {{PATH|/etc/fish/conf.d}}.
 +
 
 +
=== Completions ===
 +
 
 +
{{c|fish}} has extensive completions support. Included in the source are many detailed contributed completions, and basic coverage for other things is provided by generation from {{c|man}} pages. For details on file organisation and precedence have a look at https://fishshell.com/docs/current/completions.html#where-to-put-completions
 +
 
 +
=== Environment variables ===
 +
 
 +
The [[Handbook:AMD64/Working/EnvVar|handbook]] explains how to set environment variables globally in the Gentoo system, for all users and the default POSIX shell. Anything using PAM will get the environment with pam_env but it's likely that many shells will start without that so extra configuration is needed.
 +
 
 +
Fish uses the same {{c|set}} command for all types of variables, with -gx (Global scope, eXported) being used for variables loaded from the environment, and has useful options like --prepend and --append.
 +
 
 +
{{FileBox|filename=~/.conf/fish/config.fish|title=Append a PATH variable in fish shell|lang=bash|1=
 +
set -gxa PATH "$HOME/.local/bin:"
 +
}}
 +
 
 +
{{FileBox|filename=~/.conf/fish/config.fish|title=Prepend a PATH variable in fish shell|lang=bash|1=
 +
set -gxp PATH "$HOME/.local/bin:"
 +
}}
  
−
In Gentoo, the login shell (the shell started after a user logs in, as defined in {{path|/etc/passwd}}) sources {{Path|/etc/profile}}, which in turn sources {{Path|/etc/profile.env}}. This is needed to set up a functioning Gentoo environment, so a working POSIX shell is essential (see [[Login#Login shell in Gentoo|login shell in Gentoo]] for details).
+
== Fish as a default shell ==
  
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{{c|fish}} can ''not'' read these files, as it is not POSIX compatible, thus it is ''strongly advised '''not''' to set {{c|fish}} '' as the login shell for any user.
+
In Gentoo a POSIX compatible login shell is needed to configure the environment (see [[Login#Login shell in Gentoo|login shell in Gentoo]] for details), you must only use {{c|chsh}} to change the shell for a user or do it at creation. Linking /bin/sh to Fish will break your system, see eslect sh for a list of POSIX shells that are suitable for this role.
  
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There is no reliable way to avoid this (see {{Bug|545830}}), however there is a '''good workaround''', as explained in the next section.
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== Starting Fish directly ==
  
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Those who nevertheless want to set {{c|fish}} as a default login shell can jump down to [[#Setting the fish shell as the login shell|setting the {{c|fish}} shell as the login shell]], though this is highly discouraged and can result in difficult issues.
+
To get partial environment support you can directly source the /etc/profile.env file, which is capable of handling this type of file now.
  
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=== fish as a default shell with bash as the login shell ===
+
{{FileBox|filename=/etc/fish/config.fish|lang=bash|1=
 +
[...]
 +
status -l ; and test -f /etc/profile.env ; and source /etc/profile.env
 +
}}
 +
 
 +
This does not cover the scripts in /etc/profile.d, so if you need anything from there you will have to write your own version in Fish and then something like this to the system config so that root also gets the variables.
 +
 
 +
{{FileBox|filename=/etc/fish/config.fish|lang=bash|1=
 +
[...]
 +
status -l ; and for x in (find '/etc/profile.d/' -type f -name '*.fish')
 +
  source $x
 +
end
 +
}}
  
−
The following workaround allows the use of {{c|fish}} by default, upon login or on starting a terminal emulator. This solution uses {{path|~/.bashrc}} as a wrapper to have {{c|fish}} inherit the environment from the login shell, which is left as a bash.
+
== Starting Fish from Bash ==
 +
The following workaround allows the use of {{c|fish}} on login or on starting a terminal emulator. This solution uses {{path|~/.bashrc}} as a wrapper to have {{c|fish}} inherit the environment from the login shell, which is left as a bash.
  
 
Add the following to the user's {{path|~/.bashrc}}, making sure it's placed below the test for an interactive shell, e.g. at the end of the file:
 
Add the following to the user's {{path|~/.bashrc}}, making sure it's placed below the test for an interactive shell, e.g. at the end of the file:
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This solution was suggested [https://github.com/fish-shell/fish-shell/issues/3665#issuecomment-268527236 by one of the {{c|fish}} developers] and the [https://wiki.archlinux.org/index.php/Fish#Not_setting_fish_as_default_shell Arch wiki].
 
This solution was suggested [https://github.com/fish-shell/fish-shell/issues/3665#issuecomment-268527236 by one of the {{c|fish}} developers] and the [https://wiki.archlinux.org/index.php/Fish#Not_setting_fish_as_default_shell Arch wiki].
−
 
−
=== Setting the fish shell as the login shell ===
 
−
 
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{{Warning|After setting {{c|fish}} as the login shell there probably will be entries missing in the <var>PATH</var> variable and some packages that rely on {{Path|/etc/profile.d}} will broken.}}
 
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Those who really wish to make {{c|fish}} their login shell can still technically do so. This is not recommended and can result in a broken system:
 
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{{Cmd|chsh -s /bin/fish}}
 
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== Configuration ==
 
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{{c|fish}} starts by executing commands in {{Path|~/.config/fish/config.fish}}. The file can be created if it does not exist.
 
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Since the version 2.0 it is possible to configure fish from a web browser session by running:
 
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{{Cmd|fish_config}}
 
−
 
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=== Completions ===
 
−
 
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{{c|fish}} can generate completions from man pages. To generate completions run:
 
−
 
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{{Cmd|fish_update_completions}}
 
−
 
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=== Environment variables ===
 
−
 
−
The [[Handbook:AMD64/Working/EnvVar|handbook]] explains how to set environment variables globally, for all users, and for the default shell (bash).
 
−
 
−
Fish shell sets environment variables in a different way:
 
−
 
−
{{FileBox|filename=~/.conf/fish/config.fish|title=Append the PATH variable for fish shell|lang=bash|1=
 
−
set -gx PATH "$PATH:$HOME/.local/bin:"
 
−
}}
 
−
 
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== Troubleshooting ==
 
−
 
−
=== Garbled display ===
 
−
 
−
The output of a shell can, in some conditions, become corrupt. See the [[Terminal_emulator#Garbled_display|terminal emulator]] article for instructions to help fix this.
 
  
 
== See also ==
 
== See also ==

Revision as of 17:40, 14 June 2022

fish - the friendly interactive shell - is a smart and user-friendly command line shell for OS X, Linux, and the rest of the family. fish includes features like syntax highlighting, autosuggest-as-you-type, and fancy tab completions that just work, with no configuration required.

See the terminal emulator article for some general usage pointers.

Important
See caveats section for how to use fish as a user's default shell.
Warning
fish is not suitable for linking to /bin/sh, See the eselect sh utility for managing POSIX shells


Installation

Emerge

Install app-shells/fish:

root #emerge --ask app-shells/fish

Configuration

The command fish_config can manage settings on in the shell or a web browser. To use a web browser you also need a $BROWSER env var, an example of setting this would be set -gx BROWSER /usr/bin/librewolf run in the shell, added to the user or system as below, or in the usual bash format in /etc/env.d if you follow the steps in 'Fish as a default shell'

The main files for configuration are /etc/fish/config.fish, which is called by every shell, and the user init file ~/.config/fish/config.fish which does not exist by default. If the user file exists the system file is still used automatically.

Both config/fish and /etc/fish can contain a Template:PATH directory, this is handled slightly differently in that named files in the user's conf.d will prevent a file of the same name being sourced from Template:PATH.

Completions

fish has extensive completions support. Included in the source are many detailed contributed completions, and basic coverage for other things is provided by generation from man pages. For details on file organisation and precedence have a look at https://fishshell.com/docs/current/completions.html#where-to-put-completions

Environment variables

The handbook explains how to set environment variables globally in the Gentoo system, for all users and the default POSIX shell. Anything using PAM will get the environment with pam_env but it's likely that many shells will start without that so extra configuration is needed.

Fish uses the same set command for all types of variables, with -gx (Global scope, eXported) being used for variables loaded from the environment, and has useful options like --prepend and --append.

FILE ~/.conf/fish/config.fishAppend a PATH variable in fish shell
set -gxa PATH "$HOME/.local/bin:"
FILE ~/.conf/fish/config.fishPrepend a PATH variable in fish shell
set -gxp PATH "$HOME/.local/bin:"

Fish as a default shell

In Gentoo a POSIX compatible login shell is needed to configure the environment (see login shell in Gentoo for details), you must only use chsh to change the shell for a user or do it at creation. Linking /bin/sh to Fish will break your system, see eslect sh for a list of POSIX shells that are suitable for this role.

Starting Fish directly

To get partial environment support you can directly source the /etc/profile.env file, which is capable of handling this type of file now.

FILE /etc/fish/config.fish
[...]
status -l ; and test -f /etc/profile.env ; and source /etc/profile.env

This does not cover the scripts in /etc/profile.d, so if you need anything from there you will have to write your own version in Fish and then something like this to the system config so that root also gets the variables.

FILE /etc/fish/config.fish
[...]
status -l ; and for x in (find '/etc/profile.d/' -type f -name '*.fish')
  source $x
end

Starting Fish from Bash

The following workaround allows the use of fish on login or on starting a terminal emulator. This solution uses ~/.bashrc as a wrapper to have fish inherit the environment from the login shell, which is left as a bash.

Add the following to the user's ~/.bashrc, making sure it's placed below the test for an interactive shell, e.g. at the end of the file:

FILE ~/.bashrc
[...]
# Use fish in place of bash
# keep this line at the bottom of ~/.bashrc
[ -x /bin/fish ] && SHELL=/bin/fish exec fish

When bash is started as an interactive shell, this will automatically launch fish for the user, once bash has fully initialized the correct system environment. It will also set the SHELL environment variable to /bin/fish in fish.

Log into a new virtual console to test. Keeping open the current terminal may permit troubleshooting in case of issue with the new configuration.

Note
When set up this way, launching an interactive bash prompt will drop to fish because of the line added to ~/.bashrc. To launch bash, ignore ~/.bashrc (beware that any commands in ~/.bashrc will not be executed):
user $bash --rcfile /etc/profile

This solution was suggested by one of the fish developers, the Arch wiki and Gentoo devs [1].

fish as shell with bass to create and import environment

Once fish is installed, install bass, which will permit fish to source /etc/profile on startup. bass is a utility to execute commands in bash and replay the environment variable changes in fish. The bass site has instructions for different installation methods, such as with the fisher plugin manager or OMF. We will explain here how to install bass manually, as this is the most basic method, however a plugin manager is arguably preferable.

Move into or create a base directory for the bass repository, for example:

user $cd ~/.local/opt

Clone the bass repository (requires git), and move into the repository directory:

user ~/.local/opt $git clone https://github.com/edc/bass; cd bass

Install bass:

user ~/.local/opt/bass $make install

With bass, one can now have fish inherit the system-wide environment variables on startup, from bash.

Add the following line to ~/.config/fish/config.fish, above any other commands that would need the environment to be set up (config.fish may need to be created):

FILE ~/.config/fish/config.fish
bass source /etc/profile

Finally, restart fish if it is already running.

This solution was suggested by one of the fish developers and the Arch wiki.

See also

  • Shell — command-line interpreter that provides a text-based interface to users

External resources

Retrieved from "https://wiki.gentoo.org/index.php?title=Fish&oldid=1072403"