The grep command searches the given input FILEs for lines containing a match or a text string.
grep command syntax
The syntax is:
grep -options "text string to search” directory-path
OR
grep [option] "text string to search” directory-path
OR
grep -r "text string to search” directory-path
OR
grep -r -H "text string to search” directory-path
OR
egrep -R "word-1|word-2” directory-path
OR
egrep -w -R "word-1|word-2” directory-path