Declare the variable

zsh-syntax-highlighting / highlighters / pattern

This is the pattern highlighter, that highlights user-defined patterns.

How to tweak it

To use this highlighter, associate patterns with styles in the ZSH_HIGHLIGHT_PATTERNS associative array, for example in ~/.zshrc:

# Declare the variable
typeset -A ZSH_HIGHLIGHT_PATTERNS

# To have commands starting with `rm -rf` in red:
ZSH_HIGHLIGHT_PATTERNS+=('rm -rf *' 'fg=white,bold,bg=red')

The syntax for values is the same as the syntax of "types of highlighting" of the zsh builtin $zle_highlight array, which is documented in the zshzle(1) manual page.