Fish

fish - the friendly interactive shell.

fish 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.

Emerge
Install :

Caveats
Fish is not a POSIX 1003.1 compatible shell. It does not read, , or the directories.

It is advised not to set fish as a default login shell. see for more details.

Some packages install files into and are not compatible with fish. Not setting fish as system wide or user default allows the standard shell scripts to run on startup, ensures the environment variables are set correctly, and generally reduces the issues associated with using a non-Bash compatible terminal like fish. Those who really, truly, actually wish to set the fish shell can jump down to Setting the fish shell as the login shell. For all other readers, it is best to proceed down the .bashrc safety net path.

.bashrc safety net
The following is a trick suggested by one of the fish developers and the Arch wiki. This enables the shell to inherit the  environment (which written in and should be executed by the  shell):

Please note it should not be run for non-interactive shells, so make sure it's placed below the test for interactive shell.

Launch using:

Setting the fish shell as the login shell
Those who really wish make their default login shell can change the shell:

Configuration
fish starts by executing commands in. You can create it if it does not exist. Since the version 2.0 it is possible to configure fish within a web browser session by running:

Fish can generate completions from man pages. To generate completions run:

External resources

 * fish first steps tutorial
 * fish related question on stackoverflow
 * arch-wiki fish entry