Shell Technical Comparison: Zsh, Bash, and POSIX Compliance

This technical comparison examines the core differences between POSIX shells, Bash, and Zsh, highlighting their unique roles in scripting and interactive computing. While POSIX serves as the universal standard for portability, Bash functions as a widely compatible extension that balances standard compliance with user-friendly enhancements. In contrast, Zsh is described as a "kitchen sink" shell, offering advanced features like recursive globbing, floating-point arithmetic, and a sophisticated programmable completion system. The text emphasizes that Zsh is often preferred for personal use due to its extensive customization options and plugin ecosystems, such as Oh-My-Zsh. However, the author warns that Zsh's unique behaviors, such as its 1-indexed arrays and different word-splitting rules, can create compatibility issues when running scripts designed for Bash. Ultimately, the source positions Bash as the superior choice for universal scripting, while recommending Zsh for a more powerful and tailored interactive terminal experience.