compinit

compinit is a built-in function of the Z shell (zsh) that initializes the shell’s programmable completion system. It activates, configures, and loads completion definitions and helpers so that zsh can offer context-aware suggestions for commands, options, arguments, and filenames. The completion framework relies on definitions loaded from various sources and registered completion functions that integrate with the shell’s input handling.

Usage in typical setups involves loading the function and invoking it during startup:

autoload -Uz compinit

compinit

The autoload declaration makes the function available without loading it immediately, while compinit performs the actual initialization, scanning appropriate paths for completion definitions and preparing the system for interactive use.

Cache and performance: To speed startup, compinit builds a compiled cache of completion data and stores it in a file named .zcompdump in the user’s home directory. On subsequent shells, the cache is read to avoid reprocessing completion definitions, improving responsiveness. If the cache is missing, outdated, or corrupted, it can be deleted (for example, via rm ~/.zcompdump*) and compinit can be run again to regenerate it.

Security and compatibility: compinit conducts checks for security and integrity, including detection of insecure directories in the completion search paths. If issues are detected, it may warn the user or adjust behavior to prevent executing untrusted code. The function also supports a number of options to customize its behavior and compatibility with different setups and versions of zsh.

See also: Z shell, programmable completion, compdef, _complete, fpath.