写一个简单的shell命令解释器

/*************************************************************************
#	> File Name: myshell.c
# Author: HuoZG
# mail:248786797@qq.com
# Created Time: Thu 23 Feb 2017 05:23:22 AM PST
************************************************************************/

#include<stdio.h>
#include<ctype.h> // isspace()
#include<stdlib.h> // exit()  fflush();
#include<sys/wait.h> // waitpid()
#include<unistd.h> // execvp // 需要 argv  和 命令 不需要

int main()
{
char buf[128]; // save input
while(1)
{
char path[100];

gethostname(path, sizeof(path));
printf("[test@%s ~]$", path);
fflush(stdout);
ssize_t _s = read(0, buf, sizeof(buf)-1);
if(_s >0)
{// read sucess
buf[_s-1] = '\0';
}
else
{// read failed
printf("read!\n");
return 1;
}

char* myargv[32];// get command
myargv[0] = buf;
int index = 1;
char* start = buf;
while(*start)
{
if(isspace(*start))
{
*start = '\0';
start++;
myargv[index] = start;
index++;
}
else
{
start++;
}
}

myargv[index] = NULL;
pid_t id = fork();
if(id < 0 )
{
printf("create failed\n");
return 2;
}
else if(id == 0)
{//child
execvp(myargv[0], myargv);
printf("command not found\n");
return 3;
}
else
{// father
int status = 0;
ssize_t ret = waitpid(id, &status, 0);
if(ret > 0 && WIFEXITED(status))
{
//printf("wait sucess ;status:%d \n", WEXITSTATUS(status));
}
else
{
perror("waitpid");
}
}
}
return 0;
}