STAT(2)

NAME
stat, lstat, fstat - get file status

SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int stat(const char *path, struct stat *buf)
int lstat(const char *path, struct stat *buf)
int fstat(int fd, struct stat *buf)

DESCRIPTION
Stat obtains information about the file path. Read, write or execute permission of the named file is not required, but all directories listed in the path name leading to the file must be reachable.

Lstat is like stat except in the case where the named file is a symbolic link, in which case lstat returns information about the link, while stat returns information about the file the link references.

Fstat obtains the same information about an open file referenced by the argument descriptor, such as would be obtained by an open call. Pipe descriptors look like named pipes with a link count of zero. The st_size field of pipes or named pipes shows the amount of bytes currently buffered in the pipe.

Buf is a pointer to a stat structure into which information is placed concerning the file. The contents of the structure pointed to by buf is as follows:

struct stat {
	dev_t	st_dev;	/* device inode resides on */
	ino_t	st_ino;	/* this inode's number */
	mode_t	st_mode;	/* file mode, protection bits, etc. */
	nlink_t	st_nlink;	/* number or hard links to the file */
	uid_t	st_uid;	/* user-id of the file's owner */
	gid_t	st_gid;	/* group-id of the file's owner */
	dev_t	st_rdev;	/* the device type, for inode that is device */
	off_t	st_size;	/* total size of file */
	time_t	st_atime;	/* time of last access */
	time_t	st_mtime;	/* time of last data modification */
	time_t	st_ctime;	/* time of last file status change */
};

st_atime
    Time when file data was last read or modified. Changed by the following system calls: mknod(2), utime(2), read(2), and write(2). For reasons of efficiency, st_atime is not set when a directory is searched, although this would be more logical.

st_mtime
    Time when data was last modified. It is not set by changes of owner, group, link count, or mode. Changed by the following system calls: mknod(2), utime(2), write(2).

st_ctime
    Time when file status was last changed. It is set both both by writing and changing the i-node. Changed by the following system calls: chmod(2) chown(2), link(2), mknod(2), rename(2), unlink(2), utime(2), write(2).

The file type information in st_mode has bits:

#define S_IFMT	0170000	/* type of file */
#define    S_IFIFO	0010000	/* named pipe */
#define    S_IFCHR	0020000	/* character special */
#define    S_IFDIR	0040000	/* directory */
#define    S_IFBLK	0060000	/* block special */
#define    S_IFREG	0100000	/* regular */
#define    S_IFLNK	0120000	/* symbolic link */

The mode bits 0007777 encode set-uid/gid bits and permission bits (see chmod(2)).

RETURN VALUE
Upon successful completion a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS
Stat and lstat will fail if one or more of the following are true:

[ENOTDIR]
    A component of the path prefix is not a directory.

[ENAMETOOLONG]
    The path name exceeds PATH_MAX characters.

[ENOENT]
    The named file does not exist.

[EACCES]
    Search permission is denied for a component of the path prefix.

[ELOOP]
    Too many symbolic links were encountered in translating the pathname.

[EFAULT]
    Buf or name points to an invalid address.

[EIO]
    An I/O error occurred while reading from or writing to the file system.

Fstat will fail if one or both of the following are true:

[EBADF]
    Fildes is not a valid open file descriptor.

[EFAULT]
    Buf points to an invalid address.

[EIO]
    An I/O error occurred while reading from or writing to the file system.

SEE ALSO
chmod(2), chown(2), utime(2).