.zsh File — Z Shell Script

ZSH files are scripts written for the Z Shell, an extended Bourne shell with many improvements over Bash. Zsh became the default shell on macOS starting with Catalina (2019) and has gained significant popularity through the Oh My Zsh framework. ZSH files can use advanced features including programmable command completion with descriptions, spelling correction, shared history across sessions, extended globbing with qualifiers (ls *(.) for files only, *(/) for directories), floating point arithmetic, anonymous functions, and powerful prompt customization through prompt themes and the Powerlevel10k theme. Zsh's completion system is one of its strongest features — it provides context-aware completion for commands, options, file paths, hostnames, and even git branches with descriptions. The .zsh extension is used for both scripts and configuration fragments that are sourced by Oh My Zsh plugins and themes. Zsh configuration uses .zshrc (interactive config), .zshenv (all invocations), .zprofile (login shells), and .zlogin. While highly compatible with Bash scripts, Zsh has subtle differences in array indexing (1-based vs 0-based), word splitting, and globbing behavior that can cause portability issues.