Fish – A Smart and User-Friendly Interactive Shell for Linux

The Friendly Interactive Shell which is commonly called and abbreviated as FISH is a shell for UNIX and UNIX like Operating System. It is released under GNU General Public License v2.

FISH is a user-friendly, interactive shell designed to work with any other shell like bash or ZSH. It is designed in such a way that users get powerful features that is easy to discover, remember and use. Unlike other shell which disables various features by default to save system resource, FISH keeps all of them enabled by default so that you can make most out of it.

Features of FISH

1. Interactive and User-friendly
2. Powerful features
3. Simple, clean and Consistent.
4. Exotic in the sense that syntax not independent and isn’t derived from Bourne Shell or C shell.
5. Search as you type feature ensures automatic suggestions based upon current directory and history.
6. Select suggestions using arrow key.
7. Advanced Tab completion supported.
8. Syntactic rules prefer features as commands and not syntax.
9. Help command to view FISH documentation in HTTP Web Browser.
10. Support for Universal Variable so user can assign permanent variable, remains unaffected at reboot/shutdown.
11. Syntax highlighting and extensive error checking.
12. X clipboard supported.
13. Glorious VGA Color. 256 terminal colors supported.
14. Web-based configuration.

Installation of FISH (Friendly Interactive Shell) in Linux

Fish packages can be installed on all Linux distributions using Fish repositories, the best way is to add the repository to your system package manager using the following steps as per your distributions:

On Debian Systems

Add the following repository to Debian 8/7 and install manually as shown.

---------------- On Debian 8 ----------------
# echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/2/Debian_8.0/ /' >> /etc/apt/sources.list.d/fish.list 
# apt-get update
# apt-get install fish

---------------- On Debian 7 ----------------
# echo 'deb http://download.opensuse.org/repositories/shells:/fish:/release:/2/Debian_7.0/ /' >> /etc/apt/sources.list.d/fish.list 
# apt-get update
# apt-get install fish

On Ubuntu Systems

On Ubuntu (all supported releases) execute the following commands:

$ sudo add-apt-repository ppa:fish-shell/nightly-master
$ sudo apt-get update
$ sudo apt-get install fish

On Fedora Systems

On Fedora (22, 21, 20) run the following commands as root:

---------------- On Fedora 22 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/Fedora_22/shells:fish:release:2.repo
# yum install fish

---------------- On Fedora 21 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/Fedora_21/shells:fish:release:2.repo
# yum install fish

---------------- On Fedora 20 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/Fedora_20/shells:fish:release:2.repo
# yum install fish

On CentOS Systems

On CentOS (7 and 6) run the following commands as root:

---------------- On CentOS 7 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/CentOS_7/shells:fish:release:2.repo
# yum install fish

---------------- On CentOS 6 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/CentOS_6/shells:fish:release:2.repo
# yum install fish

On RHEL Systems

On RHEL (7 and 6) run the following commands as root:

---------------- On RHEL 7 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/RHEL_7/shells:fish:release:2.repo
# yum install fish

---------------- On RHEL 6 ----------------
# cd /etc/yum.repos.d/
# wget http://download.opensuse.org/repositories/shells:fish:release:2/RedHat_RHEL-6/shells:fish:release:2.repo
# yum install fish

How to Use Fish Shell

1. First time when you start fish, you should see this on the terminal:

$ fish

2. Check version of fish installed.

$ echo $FISH_VERSION

3. See how auto-suggestion is working in FISH.

$ date
$ Desktop
$ locale
...

4. Call for help and you will get help in your default HTTP web browser.

$ help

5. Use Advanced Tab auto-completion followed by a incomplete string/command.

$ tty

6. Syntax highlighting as user type:

$ /usr/bin/calendar

7. Intelligent color selection automatically in real time.

$ echo "I am loving FISH <3"

8. You can check exit status of last run command.

$ echo $status

9. Make FISH your default shell.

$ chsh -s /usr/bin/fish

Enter password when prompted.

To switch back to your Previous shell do.

$ chsh -s /bin/bash

If any other shell was your default shell replace ‘/bin/bash’ with your shell. For example if it was zsh do:

$ chsh -s /bin/zsh

Caution: Check twice the path of your shell before entering. If you accidentally entered wrong path to a shell you will be thrown out of the shell, If you do this with your admin account, you will need to reset admin password and then change shell. To get rid of these hassles be extra-caution.

This shell provides output in a lucid and interactive way that it will change the way you look at Linux Shell. So much of colors, indention, highlighting of codes, auto-completion, suggestion and other features lets you concentrate on what you want to achieve and not how to achieve. This shell has been honored by being added as my default shell for my work machine. FISH is an example to those who says Linux command-line is boring.

If You are an avid Linux user and a fan of Linux command-line. This Shell is worth giving a try and it won’t disappoint you. You may like to share your experience with FISH in the comments below. Don’t forget to provide us with your valuable feedback in the comments below. Like and share us help us get spread.

Reference Link: http://fishshell.com/