ino_t  d_ino       File serial number.
char   d_name[]    Filename string of entry.

DIR
  A type representing a directory stream. The DIR type may be an incomplete type.

#include <sys/stat.h>
 
struct stat {
    dev_t      st_dev;      /* ID of device containing file */
    ino_t      st_ino;      /* Inode number */
    mode_t     st_mode;     /* File type and mode */
    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;  /* Block size for filesystem I/O */
    blkcnt_t   st_blocks;   /* Number of 512 B blocks allocated */
    /* Since POSIX.1-2008, this structure supports nanosecond
       precision for the following timestamp fields.
       For the details before POSIX.1-2008, see HISTORY.  */
    struct timespec  st_atim;  /* Time of last access */
    struct timespec  st_mtim;  /* Time of last modification */
    struct timespec  st_ctim;  /* Time of last status change */
#define st_atime  st_atim.tv_sec  /* Backward compatibility */
#define st_mtime  st_mtim.tv_sec
#define st_ctime  st_ctim.tv_sec
};

void   *iov_base  Base address of a memory region for input or output.
size_t  iov_len   The size of the memory pointed to by iov_base.

int    fd       The following descriptor being polled.
short  events   The input event flags (see below).
short  revents  The output event flags (see below).

#include <dirent.h>
 
struct dirent *readdir(DIR *dirp);

#include <dirent.h>
 
DIR *fdopendir(int fd);
DIR *opendir(const char *dirname);

The fdopendir() function shall be equivalent to the opendir() function except that the directory is specified by a file descriptor rather than by a name.

#include <dirent.h>
 
int closedir(DIR *dirp);

#include <unistd.h>
 
int chdir(const char *path);

#include <unistd.h>
 
char *getcwd(char *buf, size_t size);

#include <sys/stat.h>
 
int mkdir(const char *path, mode_t mode);

#include <stdio.h>
 
FILE *fopen(const char *restrict pathname, const char *restrict mode);

#include <stdio.h>
 
int fseek(FILE *stream, long offset, int whence);

#include <stdio.h>
 
int fclose(FILE *stream);

#include <stdio.h>
 
int fprintf(FILE *restrict stream, const char *restrict format, ...);

#include <stdio.h>
 
int fputc(int c, FILE *stream);

#include <stdio.h>
 
int fputs(const char *restrict s, FILE *restrict stream);

#include <stdio.h>
 
size_t fwrite(const void *restrict ptr, size_t size, size_t nitems,
  FILE *restrict stream);

#include <stdio.h>
 
int fscanf(FILE *restrict stream, const char *restrict format, ...);

#include <stdio.h>
 
int fgetc(FILE *stream);

#include <stdio.h>
 
char *fgets(char *restrict s, int n, FILE *restrict stream);

#include <stdio.h>
 
size_t fread(void *restrict ptr, size_t size, size_t nitems,
  FILE *restrict stream);

#include <unistd.h>
 
int link(const char *path1, const char *path2);

#include <unistd.h>
 
ssize_t readlink(const char *restrict path, char *restrict buf,
  size_t bufsize);

#include <fcntl.h>
 
int open(const char *path, int oflags, ...);

#include <unistd.h>
 
int close(int fildes);

#include <unistd.h>
 
ssize_t read(int fildes, void *buf, size_t nbyte);

#include <unistd.h>
 
ssize_t write(int fildes, const void *buf, size_t nbyte);

#include <unistd.h>
 
off_t lseek(int fildes, off_t offset, int whence);

#include <sys/uio.h>
 
ssize_t writev(int fildes, const struct iovec *iov, int iovcnt);

#include <sys/uio.h>
 
ssize_t readv(int fildes, const struct iovec *iov, int iovcnt);

#include <sys/mman.h>
 
void *mmap(void *addr, size_t len, int prot, int flags,
    int fildes, off_t off);

#include <fcntl.h>
 
int fcntl(int fildes, int cmd, ...);

#include <poll.h>
 
int poll(struct pollfd fds[], nfds_t nfds, int timeout);

#include <unistd.h>
 
int symlink(const char *path1, const char *path2);

#include <fcntl.h>
#include <sys/stat.h>
 
int lstat(const char *restrict path, struct stat *restrict buf);
int stat(const char *restrict path, struct stat *restrict buf);

The lstat() function shall be equivalent to stat(), except when path refers to a symbolic link. In that case lstat() shall return information about the link, while stat() shall return information about the file the link references.

#include <sys/stat.h>
 
int chmod(const char *path, mode_t mode);

#include <unistd.h>
 
int access(const char *path, int amode);

#include <stdlib.h>
 
int rand(void);
void srand(unsigned seed);

ino_t
  Used for file serial numbers.

#include <stdio.h>
 
typedef /* ... */  FILE;

An object type used for streams.

S_ISBLK(m)
  Test for a block special file.
S_ISCHR(m)
  Test for a character special file.
S_ISDIR(m)
  Test for a directory.
S_ISFIFO(m)
  Test for a pipe or FIFO special file.
S_ISREG(m)
  Test for a regular file.
S_ISLNK(m)
  Test for a symbolic link.
S_ISSOCK(m)
  Test for a socket.

S_TYPEISMQ(buf)
  Test for a message queue.
S_TYPEISSEM(buf)
  Test for a semaphore.
S_TYPEISSHM(buf)
  Test for a shared memory object.
S_TYPEISTMO(buf)
  Test macro for a typed memory object.