C-Code

/********************************************
 * fred_1.c   search pattern in input stream
 *            using simple charcter matching
 *
 * OS     :   GNU/Linux
 * compile:   gcc -Wall -o fred fred_1.c
 * example:   echo Freddy|./fred -i fred    				
 *
 * devnull    28-06-2013                
 ********************************************/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>

#define STR_LEN   62
#define BUF_LEN  254

/************
 * functions
 ************/
/* print usage on stderr */
void usage_exit( int exit_code )
{
  fprintf( stderr, "Usage: fred [-i] string\n" );
  exit(exit_code);
}

/* compare two characters */
int chrcmp( char c1, char c2, int icase )
{
	if (icase) {
		c1=toupper(c1);
		c2=toupper(c2);
	}
	return (c1==c2);
}

/* read input line from stdin */
int readln( char *line, int stripLF )
{
	int len;
	
	if (fgets(line, BUF_LEN, stdin) != NULL) {
		line[BUF_LEN]='\0';
		len=strlen(line);
		if (stripLF) {
			if (line[len-1] == '\n') {
				line[len-1] = '\0';
				len--;
			}
		}
		return len;
	}
	else
		return -1;
}

/*********
 *  main
 *********/
int main( int argc, char **argv )
{
    char linebuf[BUF_LEN+1];
    char pattern[STR_LEN+1];
    int opt, opt_icase=0;
    int cline,blen,slen,pos,p1,p2;
	int match;

    /* check options [ih] */
    while ((opt = getopt( argc, argv, "ih" )) != -1) {
      switch(opt) {
          case 'i': opt_icase=1;         break;
          case 'h': usage_exit(EXIT_SUCCESS); break;
          default : usage_exit(EXIT_FAILURE);
      }
    }

	/* check args: search string/pattern */
    if (argc-optind != 1) 
		usage_exit(EXIT_FAILURE);
    strncpy( pattern,  argv[optind], STR_LEN );
    pattern[STR_LEN] = '\0';
	slen=strlen(pattern);
	if (slen == 0) {
		fprintf( stderr, "empty search string\n" );
		return 2;
	}

	/* main loop: read lines from stdin */
	cline=0;            /* line counter */
	while ((blen=readln(linebuf,1)) >= 0) {
		cline++;
		if (blen < slen) continue;  /* input string too short */
	
		/* loop 2: parse input line */
		for (pos=0; pos<=blen-slen; pos++) {
			if (chrcmp( linebuf[pos],pattern[0],opt_icase )) {
				match=1;
				/* loop 3: verify pattern */
				for (p1=pos+1,p2=1; p2<slen; p1++,p2++) {
					if (!chrcmp( linebuf[p1],pattern[p2],opt_icase )) {
						match=0;
						break;
					}
				}
				if (match) {
					printf( "%d:%s\n", cline,linebuf );
					break;
				}
			}
		}
	}
	return 0;
}