Shell Program For Searching a String.

Below is a Simple Shell Program in C Language which Implement search command as follows

1) search first occurrence of pattern in file name

2) count no of occurrences of pattern in file name

3) search all occurrences of pattern in file name


#include <stdio.h>
#include <conio.h>
#include <process.h>
#include <string.h>


void main( int argc, char *argv[])
{
    char pattern[20],fname[20],option;

    printf("\nSearch Starts..");
    if( argc != 4 )
    {
        printf("\nInvalid number of arguments");
        return;
    }// if
    // set param
    option = *argv[1];
    strcpy(pattern,argv[2]);
    strcpy(fname,argv[3]);

    switch(option)
    {
        case 'f' :       find_first_occ(fname,pattern);
                        break;
        case 'c' :       count_all_occ(fname,pattern);
                        break;
        case 'a' :       print_all_occ(fname,pattern);
                        break;
        default  :        printf("\nInvalid option");
                        break;
    } // switch
} // main

int find_first_occ( char fname[], char pattern[])
{
    FILE *fp;
    char str[100],*ptr;
    int i,m,c,lineno;

    fp = fopen(fname,"r");
    if( fp == NULL )
    {
        printf("\nUnable to open given file");
        return;
    }

    lineno=0;
    while ( !feof(fp))
    {
        strset(str,'\0');
        fgets(str,99,fp);
        lineno++;

        ptr = strstr(str,pattern);
        if( ptr != NULL )
        {
            printf("\n lineno = %d : Line = %s", lineno,str);
            printf("\n position = %d", ptr - str +1 );
            break;
        }
    } // while
    fclose(fp);
    return;
} // find first occ


int count_all_occ( char fname[], char pattern[])
{
    FILE *fp;
    char str[100],*ptr,*ptr1;
    int count=0;

    int i,m,c,lineno;

    fp = fopen(fname,"r");

    if( fp == NULL )
    {
        printf("\nUnable to open given file");
        return;
    }

    while ( !feof(fp))
    {
        strset(str,'\0');
        fgets(str,99,fp);

        ptr1 = str;
        ptr = strstr(ptr1,pattern);

        while( ptr != NULL )
        {
            count++;
            ptr1= ptr+1;
            ptr = strstr(ptr1,pattern);
        }
    } // while
    fclose(fp);
    printf("\nPattern %s occurs %d times", pattern,count);
    return;
} // count all occ


int print_all_occ( char fname[], char pattern[])
{
    FILE *fp;
    char str[100],*ptr,*ptr1;
    int lineno=0;

    int i,m,c;

    fp = fopen(fname,"r");

    if( fp == NULL )
    {
        printf("\nUnable to open given file");
        return;
    }

    while ( !feof(fp))
    {
        strset(str,'\0');
        fgets(str,99,fp);
        lineno++;
        if( strstr(str,pattern) != NULL )
            printf("Line:%d: %s",lineno,str);

    } // while
    fclose(fp);
    return;
} // print all occurences