c program to simulate grep command

 

1. The grep filter searches a file for a particular pattern of characters, and displays all lines that contain that pattern.

Example:

if geekfile.txt contains the data below:

unix is great os. unix is opensource. unix is free os.

learn operating system.

 

Then the following command

$grep -c "unix" geekfile.txt

 

will give ouput:

2

 

as option -c prints only a count of the lines that match a pattern

Q) Example program to simulate  grep system call

#include <stdio.h>

#include<string.h>

int main()

{

    char st[1000], word[10];

    printf("enter a sentence");

    scanf(" %[^\n]s", st);

    printf("enter a search word");

    scanf(" %s",word);

    int l = strlen(st);

    int lw=strlen(word);

    char *p;

    int i=0,c=0;

    while(i<l)

    {

        p=strstr(st+i,word);

        if(p)

        {

            c++;

            i=p-st+lw;

        }

        else

            break;

    }

    printf("%s occurred %d times",word,c);

    return 0;

}