自己写shell第二天, 增加回显和显示当前路径以及当前用户

1. 使用fgets来获取当前命令

2. 使用getcwd API来获取当前路径

3. 使用getlogin_r来获取当前用户

效果：

/**
 *  jsh 程序，简单的shell程序
 *
 *  created ： jeff
 *  date:      2013.1.28
 *  version:   first version   
 *      
 *      modified: jeff
 *      date    : 2013.1.29
 *      version : v1.0
 *      reason  : 增加回显功能和显示用户以及当前目录的能力
 *
 *
 * *********************************************/

#include <stdio.h>
#include <unistd.h>

#include <stdlib.h>
#include <getopt.h>

#define VERSION \
  "jsh version 1.0.0\n"\

#define MAX_PATH_LENGTH 1024
#define MAX_COMMAND_LENGTH 1024
#define MAX_USER_LENGTH 128

#define USAGE\
  "Usage: jsh [GNU long option] [option] ...\n\
       jsh [GNU long option] [option] script-file ...\n\
  long option:\n\
           --version\n\
           --help\n"\

static struct option longOptions[]=
{
  {"version", 0, NULL,'v' },
  {"help", 0, NULL, 'h'}
};

static char user[MAX_USER_LENGTH]={0,};
static char currentWorkPath[MAX_PATH_LENGTH]={0,};
static char command[MAX_COMMAND_LENGTH]={0,};

static void usage();
static void version();
static void readopt(int argc, char** argv);

int main(int argc, char** argv)
{
    int opt = 0;
    char* path = NULL;
    int getuserret = 0; 

    if(argc<2)
    {
    	while(1)
        {
            /**
            *显示当前目录和用户
            */
            if((path=getcwd(currentWorkPath, sizeof(currentWorkPath))) == NULL)
                break;
            
            if( getuserret = getlogin_r(user, sizeof(user)) !=0)
                break;

            fprintf(stdout, "%s:%s$ ", user, currentWorkPath);
                  
            if(fgets(command, sizeof(command), stdin))
            {
                /**
                 *
                 * TODO do command stuff
                 *
                 */ 
            }else
            {
                break;
            }
      
        }
    }else
	{
        readopt(argc, argv);
    }

    return 0;
}

static void usage()
{
   fprintf(stdout, USAGE);
}

static void version()
{
   fprintf(stdout, VERSION);
}

static void readopt(int argc, char** argv)
{
    int opt=0;
	while( (opt=getopt_long(argc,argv,"vh",longOptions,  NULL)) !=EOF)
        {
            switch(opt)
            {
                case 'h':
                    usage();
                break;
                case 'v':
                    version();
                break;
                default:
                    usage();
                break;
            }

        }

}