C언어 특정 단어를 찾아서 그 라인을 지울수는 없나요?

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#define PPLENT_NAM	"pplent.txt"
#define PPLENT_OLD	"pplent.old"
#define PPLENT_TMP	"pplent.tmp"
 
struct pplent
{
	const char *name;
	int age;
	const char *email;
};
 
enum index_pplent
{
	IDX_PPL_NAME = 0,
	IDX_PPL_AGE,
	IDX_PPL_EMAIL,
	IDX_PPL_MAX
};
 
static FILE *ppl_fp = NULL;
 
void setpplent(void)
{
	if (ppl_fp == NULL)
		ppl_fp = fopen(PPLENT_NAM, "r");
	else
		fseek(ppl_fp, 0L, SEEK_SET);
}
 
static inline char *split_at(char *buf, int delim)
{
	char *s = strchr(buf, delim);
 
	if (s)
		*s++ = 0x00;
 
	return s;
}
 
struct pplent *getpplent(void)
{
	static char buf[BUFSIZ];
	static struct pplent ppl;
	char *tok, *next;
	char *toklist[IDX_PPL_MAX];
	int index;
 
	if (ppl_fp == NULL)
		return NULL;
 
	if (fgets(buf, sizeof(buf), ppl_fp) == NULL)
		return NULL;
 
	next = &buf[0];
	index = 0;
	while (index < IDX_PPL_MAX - 1)
	{
		tok = next;
		next = split_at(tok, '/');
		if (next == NULL)
			return NULL;
 
		toklist[index++] = tok;
	}
 
	tok = next;
	split_at(tok, '\n');
	toklist[index++] = tok;
 
	ppl.name = toklist[IDX_PPL_NAME];
	ppl.age = atoi(toklist[IDX_PPL_AGE]);
	ppl.email = toklist[IDX_PPL_EMAIL];
 
	return &ppl;
}
 
int putpplent(const struct pplent *p, FILE *fp)
{
	if (p == NULL || fp == NULL)
		return -1;
 
	fprintf(fp, "%s/%d/%s\n", p->name?p->name:"", p->age, p->email?p->email:"");
 
	return 0;
}
 
void endpplent(void)
{
	if (ppl_fp)
	{
		fclose(ppl_fp);
		ppl_fp = NULL;
	}
}
 
struct pplent *getpplbyname(const char *name)
{
	struct pplent *p;
 
	setpplent();
	while ((p = getpplent()))
	{
		if (!strcmp(p->name, name))
			break;
	}
	endpplent();
 
	return p;
}

int test_init_ppl(void)
{
	struct pplent ppl;
	FILE *fp = fopen(PPLENT_NAM, "w");
 
	if (fp == NULL)
		return -1;
 
	ppl.name = "malcolm";
	ppl.age = 20;
	ppl.email = "malcolm@gmail.com";
	putpplent(&ppl, fp);
 
	ppl.name = "onara";
	ppl.age = 22;
	ppl.email = "inara@gmail.com";
	putpplent(&ppl, fp);
 
	ppl.name = "zoe";
	ppl.age = 22;
	ppl.email = "zoe@gmail.com";
	putpplent(&ppl, fp);
 
	ppl.name = "hoban";
	ppl.age = 24;
	ppl.email = "hoban@gmail.com";
	putpplent(&ppl, fp);
 
	fclose(fp);
 
	return 0;
}
 
void test_list_ppl(void)
{
	struct pplent *p;
 
	setpplent();
	while ((p = getpplent()))
		printf("%s/%d/%s\n", p->name, p->age, p->email);
	endpplent();
}
 
int test_get_ppl_byname(const char *name)
{
	struct pplent *p;
 
	p = getpplbyname(name);
	if (p)
	{
		printf("%s/%d/%s\n", p->name, p->age, p->email);
		return 0;
	}
 
	printf("'%s' not found ..\n", name);
 
	return -1;
}
 
int test_ren_ppl_byname(const char *name, const char *replace)
{
	struct pplent *p;
	FILE *fp = fopen(PPLENT_TMP, "w");
 
	if (fp == NULL)
		return -1;
 
	setpplent();
	while ((p = getpplent()))
	{
		if (!strcmp(p->name, name))
			p->name = replace;
 
		putpplent(p, fp);
	}
	endpplent();
	fclose(fp);
 
	rename(PPLENT_NAM, PPLENT_OLD);
 
	return rename(PPLENT_TMP, PPLENT_NAM);
}
 
int test_add_ppl_entry(const char *name, int age, const char *email)
{
	struct pplent *p, ppl;
	FILE *fp;
 
	if (getpplbyname(name))	/* people exist */
		return -1;
 
	fp = fopen(PPLENT_TMP, "w");
	if (fp == NULL)
		return -1;
 
	setpplent();
	while ((p = getpplent()))
		putpplent(p, fp);
	endpplent();
 
	ppl.name = name;
	ppl.age = age;
	ppl.email = email;
	putpplent(&ppl, fp);
 
	fclose(fp);
 
	rename(PPLENT_NAM, PPLENT_OLD);
 
	return rename(PPLENT_TMP, PPLENT_NAM);
}
 
int test_del_ppl_byname(const char *name)
{
	struct pplent *p;
	FILE *fp = fopen(PPLENT_TMP, "w");
 
	if (fp == NULL)
		return -1;
 
	setpplent();
	while ((p = getpplent()))
	{
		if (!strcmp(p->name, name))
			continue;
 
		putpplent(p, fp);
	}
	endpplent();
	fclose(fp);
 
	rename(PPLENT_NAM, PPLENT_OLD);
 
	return rename(PPLENT_TMP, PPLENT_NAM);
}
 
int main(void)
{
	test_init_ppl();
	printf("* Initial people list ..\n");
	test_list_ppl();
 
	printf("\n* Lookup by name 'malcolm' ..\n");
	test_get_ppl_byname("malcolm");
 
	printf("\n* Lookup by name 'dobson' ..\n");
	test_get_ppl_byname("dobson");
 
	printf("\n* Rename 'onara' to 'inara' ..\n");
	test_ren_ppl_byname("onara", "inara");
	test_list_ppl();
 
	printf("\n* Add 'river' to people list ..\n");
	test_add_ppl_entry("river", 18, "river@gmail.com");
	test_list_ppl();
 
	printf("\n* Remove 'hoban' from people list ..\n");
	test_del_ppl_byname("hoban");
	test_list_ppl();
 
	return 0;
}