You need to use the grep command. The grep command searches the given input FILEs for lines containing a match or a text string.
grep command syntax
The syntax is:
grep "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