prog3.c

linux 流文件操作

#include <stddef.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>
#define SHELL "/bin/sh"

int mainint argc,char *argv[]
{
	int status1;
	pid_t pid1;
	char cmd[100];
	while(1)
	{
		printf("please enter the command,and type 'quit' to exit this program:\n");
		scanf("%s",cmd);
		if(strcmp(cmd,"quit")==0)
			break;
		pid1=fork();
		status1=my_system(cmd,pid1);
		printf("my pid is %d,the exit status is %d\n",pid1,status1);
	}
	return 0;			
}
int my_system(const char *command,pid_t pid)
{
	int status;
	if(pid==0)
	{
		//child process,execute the command
		execl(SHELL,SHELL,"-c",command,NULL);
		_exit(EXIT_FAILURE);
	}
	else if(pid<0)
		//fork failed,report failure
		status=-1;
	else
		//parent process,wait the end of child
		if(waitpid(pid,&status,0)!=pid)
			status=-1;
	return status;
}