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Yash

Yash, yet another shell, is a POSIX-compliant command line shell written in C99 (ISO/IEC 9899:1999). Yash is intended to be the most POSIX-compliant shell in the world while supporting features for daily interactive and scripting use. Notable features are:

Global aliases
Arrays
Socket redirection, pipeline redirection, and process redirection
Brace expansion and extended globbing
Fractional numbers in arithmetic expansion
Prompt command and command-not-found handler
Command line completion with predefined completion scripts for more than 100 commands
Command line prediction based on command history

Yash can be modified/redistributed under the terms of the GNU General Public License (Version 2) but the use of this program is without any warranty.

The source code is versioned in the Git repository.

Current Development Status

Yash now fully supports POSIX.1-2008 (IEEE Std 1003.1, 2016 Edition) except for the limitations listed in README.

Yash is stable. Maintenance updates are released once or twice a year. For the change history, see NEWS.

Requirements

Yash is supposed to build and run on any POSIX.1-2001 environment with the Software Development Utilities and the C-Language Development Utilities options. Currently, yash is mainly tested on Fedora.

Installation

The source tarball can be downloaded from the Releases page. (See the release list or older versions.)

Yash is available in most package managers, here is how to install Yash:

Package Manager	Unix System	Command
DNF	Fedora	`dnf install yash`
APT	Debian / Ubuntu	`apt install yash`
MacPorts	macOS	`port install yash`
Homebrew	macOS	`brew install yash`
pkg	FreeBSD	`pkg install yash`
pkgin	NetBSD	`pkgin install yash`
pkg_add	OpenBSD	`pkg_add yash`
Portage	Gentoo	`emerge --ask app-shells/yash`

A more complete list of packages is available from Repology.

After installation, enter yash in the terminal to start yash. The manual can be viewed by man yash.

Basic Configuration

Initialization scripts

When yash is started as a login shell, it reads ~/.yash_profile. This file is a shell script in which you define environment variables using the export command.

When yash is started for an interactive use, it reads ~/.yashrc (after reading ~/.yash_profile if it is a login shell also). In this file, you make other configurations such as aliases, prompt strings, key bindings for command line editing, and command-not-found handler. Use the sample yashrc as a template for your ~/.yashrc.

Making yash your login shell

In many Unix-like OSes, a shell must be listed in /etc/shells to be set as a login shell. Edit this file and ensure that the path to yash is written in the file.

Then, run the chsh command in the terminal and follow instructions from the command. Depending on your system, you may have to use another command to change the login shell. See documentation on your system.