This is a basic prototype written in C to search for words in different set of files.
# build program
$ make simple-grep
cc -Wall -g simple-grep.c -o simple-grep
# search for the words "this", "is", and "mehrdad"
# in files listed in .filelist
this : found in test.txt ->line: 1
this : found in test.txt ->line: 2
is : found in test.txt ->line: 1
is : found in test.txt ->line: 2
mehrdad : found in test1.txt ->line: 1