hash

Every shell makes you choose. Bash is everywhere but feels stuck in 1989. Zsh gets you modern features if you install a plugin manager, a framework, a theme, and then wait for your prompt to load. Fish gives you everything out of the box but breaks POSIX compatibility, so half your scripts and muscle memory stop working. Nushell reimagines everything from scratch, which is exciting until you need to run a for loop the way you’ve done it for twenty years.

I wanted a shell that didn’t make me choose. So I built hash.

hash is a POSIX-compliant command line interpreter written in C. It runs on Linux, macOS, and FreeBSD. It ships with syntax highlighting, autosuggestions, tab completion, persistent history, and Git-aware prompts — all built in, no plugins, no frameworks, no configuration rabbit holes. One install, and it works.

What You Get Out of the Box

Syntax highlighting as you type. Commands, arguments, and operators are colored in real time so you catch typos before hitting enter.

Autosuggestions pulled from your history. Start typing and hash shows a dimmed completion inline. Accept it, ignore it, keep typing. It’s the fish feature people love most, and it’s here without leaving POSIX behind.

Git-aware prompts via a single \g escape in your PS1. It shows the current branch and status indicators — no shell functions to maintain, no plugin to configure. Just add \g to your prompt string and it works.

PS1='\e[\u@\h \W\g]\$ '

That gives you a color-coded prompt with username, hostname, working directory, Git branch with status, and a $/# indicator. The \e escape even changes color based on the exit code of your last command — green for success, red for failure.

Tab completion for commands, files, and directories. First press completes the common prefix. Second press shows all matches. Directory completions include trailing slashes so you can keep tabbing deeper.

Persistent history across sessions with all the controls you’d expect: !! to repeat the last command, !n by number, !prefix for pattern matching. History size is configurable via HISTSIZE and HISTFILESIZE. And if you prefix a command with a space, it never gets saved — useful when you’re passing secrets on the command line and don’t want them sitting in ~/.hash_history.

Full job control: background processes with &, jobs to list them, fg and bg to manage them, kill to stop them.

POSIX Compliance, Not POSIX Only

hash follows the POSIX standard. Your existing scripts work. Your if/then/else, for, while, case statements all work. Variable expansion, command substitution with $(), pipes, redirects (>, >>, <, 2>, &>), logical operators (&&, ||) — all of it works the way you expect.

But POSIX compliance doesn’t mean POSIX limitations. hash layers modern interactive features on top of a standards-compliant foundation. You get the portability of POSIX with the experience of a next-generation shell.

Functions, aliases, and builtins like cd, export, source, test, echo, alias, and history are all here. The scripting surface area covers variables ($?, $$, $0–$9, $#, $@, $*), arithmetic expansion, and the [ test command with file, string, and numeric operators.

Simple Configuration

Three files. That’s it.

• ~/.hashrc — interactive settings, aliases, prompt customization
• ~/.hash_profile — login shell environment setup
• ~/.hash_logout — runs on login shell exit

No .zshrc that sources a framework that sources plugins that source themes. No config.fish with a different syntax than every other config file on your system. Just familiar dotfiles with familiar syntax.

How hash Compares

The pattern is clear. Bash and zsh require third-party plugins for features that should be standard in 2026. Fish and nushell include those features but break compatibility. hash is the only shell in this list that gives you both.

Built for Quality

hash is compiled with -Wall -Wextra -Werror. The codebase is analyzed with SonarCloud, tested with Valgrind for memory safety, and runs through address and undefined behavior sanitizers. The test suite includes both unit tests (via the Unity framework) and integration tests. Fuzzing is part of the quality pipeline.

String operations use bounded variants throughout — no strcpy, no strcat. Input is sanitized. The code is written with the same discipline you’d expect from security-critical infrastructure.

Install

macOS (Homebrew):

brew install juliojimenez/hash/hash-shell

Debian/Ubuntu:

echo "deb [trusted=yes] https://hash-shell.org/apt/ stable main" | sudo tee /etc/apt/sources.list.d/hash-shell.list
sudo apt update && sudo apt install hash-shell

Docker:

docker pull juliojimenez/hash-shell

From source:

git clone https://github.com/juliojimenez/hash.git
cd hash
make
sudo make install

Pre-compiled binaries are also available on the releases page for Linux (x86_64, ARM64), FreeBSD (x86_64, ARM64), and macOS (Apple Silicon).

Try It

hash is Apache 2.0 licensed and on GitHub. If you’ve been meaning to upgrade from bash but don’t want to give up POSIX compatibility or wrestle with plugin managers, hash might be what you’re looking for.