Grep

https://beyondgrep.com/

https://askubuntu.com/questions/55325/how-to-use-grep-command-to-find-text-including-subdirectories

sudo apt install ack-grep

usage
grep -rHin "darknet" src   Search all files in src directory recursively, print file name and line with occurance. i is case insensitive.

ripgrep
https://www.mattlayman.com/blog/2019/supercharging-vim-blazing-fast-search/

https://github.com/BurntSushi/ripgrep/blob/master/GUIDE.md

https://github.com/mhinz/vim-grepper

https://medium.com/@sidneyliebrand/how-fzf-and-ripgrep-improved-my-workflow-61c7ca212861

https://www.youtube.com/watch?v=fP_ckZ30gbs