apue_dirent.h

#include <dirent.h>

DIR *opendir(const char *pathname); 
DIR *fdopendir(int fd);
/* Both return: pointer if OK, NULL on error */

struct dirent *readdir(DIR *dp);
/* Returns: pointer if OK, NULL at end of directory or error */

void rewinddir(DIR *dp);
int closedir(DIR *dp);
/* Returns: 0 if OK, −1 on error */

long telldir(DIR *dp);
/* Returns: current location in directory associated with dp */

void seekdir(DIR *dp, long loc);