再开子进程，freopen就不顶用了。。。
int SimShell::shell_main(char *args)//传个命令参数，模拟shell的功能主要用fork和execvp
{
//char arg[BUFSIZE];
ssize_t readbytes; //long型
char str_prompt[BUFSIZE + 1];
//while(1)
//{
freopen("/season/output.txt", "w", stdout);
//if(arg[readbytes - 1] == '\n')
//{ /* clear '\n' at end of arg */
// arg[readbytes - 1] = '\0';
//}
if(isquit(args) == 1)
{ /* check quit or not */
//break;
return 0;
}
//int dealarg(char *arg);
dealarg(args);
fprintf(stdout, "%s", shell_prompt(str_prompt));
fflush(stdout);
fclose(stdout);
//}
return 0;
}
int SimShell::dealarg(char *arg)
{
int cmdnum;
char *args[CMDNUMBER];
int argnum;
//int parse_args(char *args[], char *arg);
argnum = parse_args(args, arg);
args[argnum] = NULL;
#if DEBUG
int i;
#endif
//int get_cmdnum(char *cmd)
cmdnum = get_cmdnum(args[0]);
switch(cmdnum){
case SHELL_EMPTY:
break;
case SHELL_CD:
//int shell_cd(char *args[])
shell_cd(args);
break;
case SHELL_FORK:
//int shell_fork(char *args[])
shell_fork(args);
break;
default:
fprintf(stdout, "%s:%d: getcmd failed\n", __FILE__, __LINE__);//
break;
}
//fclose(shell_fp);
return 0;
}
/*
* fork and called exec
*/
int SimShell::shell_fork(char *args[])
{
pid_t pid[CMDNUMBER];
int status;
int fork_num;
char **p;/* point args */
char *q;/* point *args */
/* get numbers of child process*/
fork_num = 1;
p = args;
while(*p != NULL)
{
q = *p;
while(*q != '\0')
{
if(*q == '|')
{
fork_num++;
}
q++;
}
p++;
}
#if DEBUG
//fprintf(stdout, "fork_num = %d\n", fork_num);
#endif
/* case: child process number is one */
if(fork_num < 2){
//pid_t fork(void);
if((pid[0] = fork()) < 0)
{
/* error */
perror("fork");
exit(1);
}
else if(pid[0] == 0)
{
/* child process */
//int execvp(const char *file, char *const argv[]);
if(execvp(args[0], args) < 0)
{
perror("");
exit(1);
}
exit(0);
}
}
//freopen("/season/out.txt", "a+", stdout);
/* parent process */
//pid_t waitpid(pid_t pid, int *status, int options);
if(fork_num < 2)
{
waitpid(pid[0], &status, 0);
}
else
{
//int mutifork(char *args[])
status = mutifork(args);
}
return status;
}
