STAT(2) BSD System Calls Manual STAT(2)NAME
stat, lstat, fstat, fstatat — get file status
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int
stat(const char *path, struct stat *sb);
int
lstat(const char *path, struct stat *sb);
int
fstat(int fd, struct stat *sb);
int
fstatat(int fd, const char *path, struct stat *buf, int flag);
DESCRIPTION
The stat() system call obtains information about the file pointed to by
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 searchable.
Lstat() is like stat() except in the case where the named file is a sym‐
bolic link, in which case lstat() returns information about the link,
while stat() returns information about the file the link references.
The fstat() system call obtains the same information about an open file
known by the file descriptor fd.
The fstatat() system call is equivalent to stat() and lstat() except in
the case where the path specifies a relative path. In this case the sta‐
tus is retrieved from a file relative to the directory associated with
the file descriptor fd instead of the current working directory.
The values for the flag are constructed by a bitwise-inclusive OR of
flags from the following list, defined in <fcntl.h>:
AT_SYMLINK_NOFOLLOW
If path names a symbolic link, the status of the symbolic link is
returned.
If fstatat() is passed the special value AT_FDCWD in the fd parameter,
the current working directory is used and the behavior is identical to a
call to stat() or lstat() respectively, depending on whether or not the
AT_SYMLINK_NOFOLLOW bit is set in flag.
The sb argument is a pointer to a stat structure as defined by
<sys/stat.h> (shown below) and into which information is placed concern‐
ing the file.
struct stat {
dev_t st_dev; /* inode's device */
ino_t st_ino; /* inode's number */
mode_t st_mode; /* inode protection mode */
nlink_t st_nlink; /* number of hard links */
uid_t st_uid; /* user ID of the file's owner */
gid_t st_gid; /* group ID of the file's group */
dev_t st_rdev; /* device type */
#ifndef _POSIX_SOURCE
struct timespec st_atimespec; /* time of last access */
struct timespec st_mtimespec; /* time of last data modification */
struct timespec st_ctimespec; /* time of last file status change */
#else
time_t st_atime; /* time of last access */
long st_atimensec; /* nsec of last access */
time_t st_mtime; /* time of last data modification */
long st_mtimensec; /* nsec of last data modification */
time_t st_ctime; /* time of last file status change */
long st_ctimensec; /* nsec of last file status change */
#endif
off_t st_size; /* file size, in bytes */
int64_t st_blocks; /* blocks allocated for file */
u_int32_t st_blksize; /* optimal blocksize for I/O */
u_int32_t st_flags; /* user defined flags for file */
u_int32_t st_gen; /* file generation number */
};
The time-related fields of struct stat are as follows:
st_atime Time when file data last accessed. Changed by the execve(2),
mknod(2), mmap(2), read(2) and utimes(2) system calls.
st_mtime Time when file data last modified. Changed by the mknod(2),
utimes(2) and write(2) system calls.
st_ctime Time when file status was last changed (inode data modifica‐
tion). Changed by the chmod(2), chown(2), link(2), mknod(2),
rename(2), unlink(2), utimes(2) and write(2) system calls.
If _POSIX_SOURCE is not defined, the time-related fields are defined as:
#ifndef _POSIX_SOURCE
#define st_atime st_atimespec.tv_sec
#define st_mtime st_mtimespec.tv_sec
#define st_ctime st_ctimespec.tv_sec
#endif
The size-related fields of the struct stat are as follows:
st_blksize The optimal I/O block size for the file.
st_blocks The actual number of blocks allocated for the file in
512-byte units. As short symbolic links are stored in the
inode, this number may be zero.
The status information word st_mode has the following bits:
#define S_IFMT 0170000 /* type of file */
#define S_IFIFO 0010000 /* named pipe (fifo) */
#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 */
#define S_IFSOCK 0140000 /* socket */
#define S_IFWHT 0160000 /* whiteout */
#define S_ISUID 0004000 /* set user id on execution */
#define S_ISGID 0002000 /* set group id on execution */
#define S_ISVTX 0001000 /* save swapped text even after use */
#define S_IRUSR 0000400 /* read permission, owner */
#define S_IWUSR 0000200 /* write permission, owner */
#define S_IXUSR 0000100 /* execute/search permission, owner */
For a list of access modes, see <sys/stat.h>, access(2) and chmod(2).
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
error.
COMPATIBILITY
Previous versions of the system used different types for the st_dev,
st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.
ERRORSStat() and lstat() will fail if:
[EACCES] Search permission is denied for a component of the
path prefix.
[EIO] An I/O error occurred while reading from or writing to
the file system.
[ELOOP] Too many symbolic links were encountered in translat‐
ing the pathname.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or
an entire path name exceeded 1023 characters.
[ENOENT] The named file does not exist.
[ENOTDIR] A component of the path prefix is not a directory.
[EFAULT] sb or name points to an invalid address.
Fstat() will fail if:
[EBADF] fd is not a valid open file descriptor.
[EFAULT] sb points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to
the file system.
SEE ALSOaccess(2), chmod(2), chown(2), statfs(2), statvfs(2), utimes(2),
symlink(7)STANDARDS
The stat() and fstat() system calls are expected to conform to ISO/IEC
9945-1:1990 (“POSIX.1”).
HISTORY
A stat() and a fstat() system call appeared in Version 7 AT&T UNIX. A
lstat() system call appeared in 4.2BSD. The fstatat() system call
appeared in DragonFly 2.3.
BUGS
Applying fstat() to a socket (and thus to a pipe) returns a zeroed buf‐
fer, except for the blocksize field, and a unique device and inode num‐
ber.
BSD August 1, 2009 BSD
