SIGCHLD 를 이용해서 child 종료후 출력 하려 하는데 무한루프에 빠져 버립니다.

#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <signal.h>
 
#include <sys/wait.h>
#include <unistd.h>
 
#include <fcntl.h>
#include <ctype.h>
#include <signal.h>
 
void SigHandler(int);
 
 
 
int main()
{
        pid_t pid;
        char linestring[1000];
        char command_string[1000];
        char* strptr;
        int i=0;
        char* strarg[100];
 
        struct sigaction act;				// 시그널 액션 구조체
 
        act.sa_handler = SigHandler;
        sigfillset(&(act.sa_mask));
        sigaction(SIGCHLD, &act, NULL);
 
        while(1) {
                i=0;
                printf("basicshell>");
                gets(linestring);
                strptr=(char*)strtok(linestring," \n");
                if (strptr==NULL) continue;
 
                /* fork a child process */
                pid = fork();
 
                if (pid == 0) { /* child process */
                        strcpy(command_string,strptr);
                        while (strptr!=NULL) {
                                strarg[i++]=strdup(strptr);
                                strptr=(char*)strtok(NULL," \n");
                        }
                        strarg[i]=NULL;
                        execvp(command_string,strarg);
                } else { /* parent process */
                        /* parent will wait for the child to complete */
                        //waitpid(-1, NULL, WNOHANG);
 
 
                }
        }
}
 
 
 
void SigHandler( int signo )
{
    pid_t pid;
    int status;
 
    while (wait(0) > 0 );
 
 
    printf("종료된 pid = %d\n", pid );
}