simple_grep.sh

$ grep "string_to_search_in_files" "folder/to/search" -R

simple_grep_example1.sh

#search for "add_object_page" in all files within
#the current folder and its subfolders
$ grep "add_object_page" . -R

simple_grep_example2.sh

#search for "File.expand_path" in all files within
#/var/www/rails_app and its subfolders
$ grep "File.expand_path" /var/www/rails_app -R