Brush \u2013 is a command-line shell written in Rust that combines POSIX and Bash compatibility with memory safety guarantees and performance. The project aims to be a complete alternative to traditional shells, allowing for existing scripts to run and .bashrc to be used with little to no changes. This version consolidates several months of work and over 200 merged pull requests, significantly advancing the shell towards fully replacing Bash and POSIX-compliant environments.<\/p>\n
Key development areas in this release:<\/p>\n
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Bash compatibility: added set -e, set -u, pipefail, failglob, ERR handler, coprocesses, and much more;<\/li>\n
Platforms: extended support for macOS (acting as a login shell), improved performance on Windows, FreeBSD, Android, and 32-bit systems;<\/li>\n
Interactivity: added optional TOML configs, preexec\/precmd hooks, improved support for readline macros, and more.<\/li>\n<\/ul>\n
Key Improvements in Bash Compatibility<\/h4>\n
The most significant enhancements in this release include a substantial expansion of Bash capability support. Error Handling<\/strong>:<\/p>\n
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set -e (errexit) \u2013 immediate exit on error;<\/li>\n
set -u (nounset) \u2013 error upon accessing an undeclared variable;<\/li>\n
pipefail \u2013 the return code of a pipeline is determined by the last failing command;<\/li>\n
failglob \u2013 no matches for a glob expression now results in an error.<\/li>\n<\/ul>\n
Handlers (Traps) and Coprocesses<\/strong>:<\/p>\n
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ERR handler \u2013 allows executing commands upon encountering an error;<\/li>\n
Coprocesses (coproc) \u2013 launching background processes with bidirectional communication.<\/li>\n<\/ul>\n
Built-in Commands<\/strong>:<\/p>\n
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enhanced handling of many arithmetic constructions, including high-base literals, overflows, and assignment operators;<\/li>\n
fixes and improvements affecting built-in commands: caller, read, getopts, printf, and others.<\/li>\n<\/ul>\n
Extension of Platform Support:<\/h4>\n
Release v0.4.0 makes the shell available on a wider range of devices:<\/p>\n
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macOS: fixed an issue causing the shell to hang on login. Brush can now be used as a login shell;<\/li>\n
Windows: improved path handling, added emulation of \/dev\/null, greatly enhancing usability on Windows;<\/li>\n
FreeBSD and Android: build support for these platforms;<\/li>\n<\/ul>\n
Interactive capabilities and API<\/h4>\n
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Configuration<\/strong>: added support for an optional TOML config file (~\/.config\/brush\/config.toml) for brush-specific settings;<\/li>\n
Customization<\/strong>: implemented zsh styles for preexec\/precmd hooks (behind an experimental flag), useful for creating custom prompts and timing tools;<\/li>\n
API for developers<\/strong>: the Shell type is now parameterized by extensions (ShellExtensions), allowing developers to add their own built-in commands and change variable behavior without forking the project;<\/li>\n
![\"Brush](\"\/wp-content\/uploads\/2026\/05\/deb96524d1d6aa343c36a9ae0b05d47e.jpg\")
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