TL;DR usegrep -rG <word>

searches for all files recursively in the current directory for files that include<word> inside them

example:

$echo"Use Markdown to write and format posts."> tmp.txt$cattmp.txt Use Markdown to write and format posts.

$grep-rH"Markdown"tmp.txt:Use Markdown to write and format posts.

this is naturally case-sensitive. to ignore cases, add the-i option:

$grep-riH"markdown"tmp.txt:Use Markdown to write and format posts.

⚠ Beware

when using this command is large directories (with numerous files and sub-directories), beware of getting text-walled. you might see too many results.

therefore it's recommended to limit your search queries to smaller range of directories/words.