遍历Linux下的文件夹

好久不写blog了，今天上来意思一下~~

看完书实践一下，写个遍历linux系统文件树的程序，涉及到得函数有getopt(),getcwd(),

getdtablesize(),ntfw()；

#define _XOPEN_SOURCE 1 /*GLIBC要求*/
#define _XOPEN_SOURCE_EXTENDED 1
#include<stdio.h>
#include<ftw.h>
#include<error.h>
#include<limits.h>
#include<unistd.h>
#include<stdlib.h>
#include<getopt.h>
int process(const char* file, /*在nftw()函数中调用的回调函数*/
            const struct stat* sb,
            int typeflag,struct FTW* ftwbuf);
int usage(char* str) /*出错打印提示函数*/
{
    fprintf(stderr,"usage: %s\n",str);
    exit(-1);
    }
int main(int argc,char** argv)
{
    char ch;
    int flag = FTW_PHYS,fdnum,i,ft;
    char start[1024],finish[1024];
    while((ch = getopt(argc,argv,":f")) != -1)/*解析选项*/
       {
           switch(ch){
                case 'f': /*设置FTW_CHDIR标志，该标志表示要打开该目录，要先进入该目录*/
                    flag |= FTW_CHDIR;break;
                default:
                    usage("invalid option");
                }
    }
    
    if(optind == argc)
       usage(argv[0]);
       
    /*空余文件描述符*/
    fdnum = getdtablesize() - 5; /*由于nftw调用如果很深可能会耗尽文件描述符，所以做一些设置*/
    
    getcwd(start,sizeof(start)); /*保存开始时的目录，以后测试用*/
    for(i = 2;i < argc;i++)
      {
          ft = nftw(argv[i],process,fdnum,flag); /*nftw()调用部分*/
          if(ft != 0)
              perror("nftw"); /*错误提示*/
    }
    getcwd(finish,sizeof(finish)); /*退出时的目录，测试用*/
    if((flag&FTW_CHDIR) != 0)
     {
         printf("the start file is:%s\n",start);
         printf("the finish file is:%s\n",finish);
    }
       
    
    
    
    return 0;
    }
    
int process(const char* file,
            const struct stat* sb,
            int typeflag,struct FTW* ftwbuf)
{
     int level = ftwbuf->level; /*为以下打印的时候缩进使用*/
     char* name = file + ftwbuf->base; /*name指针指向文件名的第一个字符*/
     
     printf("%*s",level*4," "); /*层次缩进*/
     
     switch(typeflag) /*为相应文件类型设置输出*/
       {
           case FTW_F:
               printf("%s (file)\n",name);break;
           case FTW_D:
               printf("%s (directory)\n",name);break;
           case FTW_DNR:
               printf("%s (file can't be read)\n",name);break;
           case FTW_SL:
               printf("%s (symbolic)\n",name);break;
    }
     
    return 0;
}