[완료]컴파일 에러메세지 c 파일 수정 부탁 드립니다.

gcc -o kill-ppp kill-ppp.c
kill-ppp.c: In function ‘main’:
kill-ppp.c:16: warning: incompatible implicit declaration of built-in function ‘exit’

kill-ppp.c
===============================
#include
#include
#include
static char *trusted_env[]={"PATH=/usr/bin:/usr/sbin:/sbin:/bin",0};
main()
{
struct passwd *pwd;
int i;
uid_t uid;
for (i=0;i < NSIG;i++){ if(i!= SIGKILL && i!=SIGCHLD)
{(void) signal(i,SIG_IGN);}
}
uid=getuid();

if ( (pwd = getpwuid(uid))== (struct passwd *)0 )
exit(1);
setuid((uid_t)0);

execle("/usr/bin/killall","/usr/bin/killall","pppd",(char *)0,trusted_env);

setuid(uid);
exit(1);
}
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