• Header file: dirent.h
• Data type for a directory stream: DIR
• Data type for a single entries: struct dirent
• Functions:
  • Opening a Directory Stream
    • DIR * opendir (const char *dirname)
    • int dirfd (DIR *dirstream)
  • Reading and Closing a Directory Stream
    • struct dirent * readdir (DIR *dirstream)
    • int readdir_r (DIR *dirstream, struct dirent *entry, struct dirent **result)
    • struct dirent64 * readdir64 (DIR *dirstream)
    • int readdir64_r (DIR *dirstream, struct dirent64 *entry, struct dirent64 **result)
    • int closedir (DIR *dirstream)
• Sample code

#include <stddef.h>
#include <stdio.h>
#include <sys/types.h>
#include <dirent.h>

int main (void)
{
        DIR *dp;
        struct dirent *ep;

        dp = opendir ("./");
        if (dp != NULL)
        {
                while (ep = readdir (dp))
                puts (ep->d_name);
                (void) closedir (dp);
        }
        else
        perror ("Couldn't open the directory");

        return 0;
}

• Ref: File System Interface in The GNU C Library