在linux系统中有7中类型的文件：普通文件，目录，链接文件，字符设备文件，块设备文件，套接字文件，fifo文件。一般来说应该能猜到是普通文件和目录文件最多，但具体的数据又是多少？
为了实现这个目的需要如下两个东西：
一个文件的信息会被封装成一个结构体：
struct stat {
dev_t st_dev; /* ID of device containing file */
ino_t st_ino; /* inode number */
mode_t st_mode; /* protection */
nlink_t st_nlink; /* number of hard links */
uid_t st_uid; /* user ID of owner */
gid_t st_gid; /* group ID of owner */
dev_t st_rdev; /* device ID (if special file) */
off_t st_size; /* total size, in bytes */
blksize_t st_blksize; /* blocksize for filesystem I/O */
blkcnt_t st_blocks; /* number of blocks allocated */
time_t st_atime; /* time of last access */
time_t st_mtime; /* time of last modification */
time_t st_ctime; /* time of last status change */
};
其中st_mode成员中记载了文件类型。可以用 S_ISREG(mode)等宏去鉴别类型。
希望获得文件的状态信息又需要用到如下函数
int stat(const char *path, struct stat *buf);
int fstat(int filedes, struct stat *buf);
int lstat(const char *path, struct stat *buf);
其中的 lstat()和 stat()的不同主要是针对链接文件，stat()会返回链接文件指向的文件信息，而lstat()则是链接文件本身。
对目录进行遍历的时候，为了返回遍历得到的节点文件，还有另一种结构体
struct dirent {
ino_t d_ino; /* inode number */
off_t d_off; /* offset to the next dirent */
unsigned short d_reclen; /* length of this record */
unsigned char d_type; /* type of file */
char d_name[256]; /* filename */
};
其中的d_name成员包含了本节点项的名字信息，d_type成员包含了本节点项的文件类型信息。（实际上就用这个类型信息就足够统计文件类型了，不用再使用上面涉及到的文件信息读取函数）
遍历一个目录需要用到的函数如下
struct dirent *readdir(DIR *dir); DIR *opendir(const char *name); int closedir(DIR *dir); int chdir(const char *path); int fchdir(int fd);
完整的程序如下
//this program is work for produce count of the type of files.
//i.e: normal file, directory, symbolic file, device file and so on.
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>
//type of files
typedef enum FileType {
TYPE_LNK,
TYPE_REG,
TYPE_DIR,
TYPE_CHR,
TYPE_BLK,
TYPE_FIFO,
TYPE_SOC,
TYPE_ERR,
TYPE_CNT,
}FILETYPE;
static unsigned long count[TYPE_CNT]; //count of the type of file
static int recur = 0; //the depth of recursion
static int recur_max; //tha max value of recursion depth
typedef int ( * FUNC) ( char *pathname);
static int inline recalRecurMax( int recur, int *recur_max)
{
return *recur_max = *recur_max<recur?recur:*recur_max;
}
//identify the type of a file
static int file_type( char *pathname)
{
int ret;
struct stat buf;
ret = lstat( pathname, &buf); //could‘t use stat(), because of the link file .
if( ret<0)
{
perror(" ");
return TYPE_ERR;
}
FILETYPE type;
switch( (buf.st_mode&S_IFMT) )
{
case S_IFLNK:
type = TYPE_LNK;
break;
case S_IFREG:
type = TYPE_REG;
break;
case S_IFDIR:
type = TYPE_DIR;
break;
case S_IFCHR:
type = TYPE_CHR;
break;
case S_IFBLK:
type = TYPE_BLK;
break;
case S_IFIFO:
type = TYPE_FIFO;
break;
case S_IFSOCK:
type = TYPE_SOC;
break;
default :
type = TYPE_ERR;
}
return type;
//return the type of this file
}
static int ftw( char *rootpath, FUNC callback)
{
recur++;
recalRecurMax( recur, &recur_max); //record the max value of recursion depth
DIR *pdir;
pdir = opendir( rootpath); //open this directory
if( NULL==pdir )
{
perror(" ");
return 0;
}
int ret;
ret = chdir( rootpath); //enter this directory
if( ret<0)
{
perror(" ");
return 0;
}
struct dirent *pdirent;
do
{
pdirent = readdir( pdir); //be carefull, this function will traverse all files in this directory.
if( NULL!=pdirent)
{
int type;
type = callback( pdirent->d_name ); //count the type of file
//printf("%s, %d\n", pdirent->d_name, type);
count[type]++;
if( (DT_DIR==pdirent->d_type) //enter sub-directory
&&(strcmp( pdirent->d_name, ".") )!=0
&&(strcmp( pdirent->d_name, ".."))!=0 )
{
int ret;
ret = ftw( pdirent->d_name, callback);
if( !ret)
printf("error: %s is not a valid path\n", pdirent->d_name);
}
}
}while( NULL!=pdirent );
chdir("..");
closedir( pdir);
recur --;
return 1;
}
static void show( unsigned long count[])
{
double sum=0;
int i;
for( i=0; i< TYPE_CNT; i++)
{
sum+= count[i];
}
printf( "LNK : %ld --%%%f\n", count[TYPE_LNK], count[TYPE_LNK]*100/sum);
printf( "REG : %ld --%%%f\n", count[TYPE_REG], count[TYPE_REG]*100/sum);
printf( "DIR : %ld --%%%f\n", count[TYPE_DIR], count[TYPE_DIR]*100/sum);
printf( "CHR : %ld --%%%f\n", count[TYPE_CHR], count[TYPE_CHR]*100/sum);
printf( "BLK : %ld --%%%f\n", count[TYPE_BLK], count[TYPE_BLK]*100/sum);
printf( "FIFO : %ld --%%%f\n", count[TYPE_FIFO], count[TYPE_FIFO]*100/sum);
printf( "SOC : %ld --%%%f\n", count[TYPE_SOC], count[TYPE_SOC]*100/sum);
printf( "ERR : %ld --%%%f\n", count[TYPE_ERR], count[TYPE_ERR]*100/sum);
printf(" recur_max = %d\n", recur_max);
}
int main( int argc, char *argv[])
{
if( 2!=argc )
{
printf("usage: a.out <pathname>\n");
return 0;
}
int ret;
ret = ftw( argv[1], file_type);
show( count);
if( !ret)
printf(" %s is not a valid path\n", argv[1]);
return 0;
}
当然实际上有很多简洁的办法完成这个功能，比如ftw()等函数。
将上面的程序在自己系统中运行后,获得的结果如下
[root@localhost ftw]# ./interesting.out / LNK : 19448 --%4.339260 REG : 330217 --%73.678398 DIR : 98236 --%21.918530 CHR : 152 --%0.033914 BLK : 47 --%0.010487 FIFO : 4 --%0.000892 SOC : 83 --%0.018519 ERR : 0 --%0.000000 recur_max = 14
有趣的小程序--统计系统中不同种类文件数量,布布扣,bubuko.com
原文：http://blog.csdn.net/u012301943/article/details/23038561