Search for a regular expression only in a subset of directories

Ripgrep is a recursive line-oriented CLI search tool.
Aims to be a faster alternative to `grep`.
More information: <https://github.com/BurntSushi/ripgrep>.
Trick copyright: tl;dr; <https://github.com/tldr-pages/tldr>

rg {{regular_expression}} {{set_of_subdirs}}

click the source code to copy install rg on any operating system with command-not-found.com