stat(2) System Calls Manual stat(2)
NAME
stat, fstat, lstat, fstatat - get file status
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS#include <sys/stat.h>int stat(const char *restrict path,struct stat *restrict statbuf);int fstat(int fd, struct stat *statbuf);int lstat(const char *restrict path,struct stat *restrict statbuf);#include <fcntl.h> /* Definition of AT_* constants */
#include <sys/stat.h>int fstatat(int dirfd, const char *restrict path,struct stat *restrict statbuf, int flags);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
lstat():
/* Since glibc 2.20 */ _DEFAULT_SOURCE
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L
|| /* glibc 2.19 and earlier */ _BSD_SOURCE
fstatat():
Since glibc 2.10:
_POSIX_C_SOURCE >= 200809L
Before glibc 2.10:
_ATFILE_SOURCE
DESCRIPTION
These functions return information about a file, in the buffer pointed to
by statbuf. No permissions are required on the file itself, but—in the
case of stat(), fstatat(), and lstat()—execute (search) permission is
required on all of the directories in path that lead to the file.
stat() and fstatat() retrieve information about the file pointed to by
path; the differences for fstatat() are described below.
lstat() is identical to stat(), except that if path is a symbolic link,
then it returns information about the link itself, not the file that the
link refers to.
fstat() is identical to stat(), except that the file about which
information is to be retrieved is specified by the file descriptor fd.
The stat structure
All of these system calls return a stat structure (see stat(3type)).
Note: for performance and simplicity reasons, different fields in the
stat structure may contain state information from different moments
during the execution of the system call. For example, if st_mode or
st_uid is changed by another process by calling chmod(2) or chown(2),
stat() might return the old st_mode together with the new st_uid, or the
old st_uid together with the new st_mode.
fstatat()
The fstatat() system call is a more general interface for accessing file
information which can still provide exactly the behavior of each of
stat(), lstat(), and fstat().
If path is relative, then it is interpreted relative to the directory
referred to by the file descriptor dirfd (rather than relative to the
current working directory of the calling process, as is done by stat()
and lstat() for a relative pathname).
If path is relative and dirfd is the special value AT_FDCWD, then path is
interpreted relative to the current working directory of the calling
process (like stat() and lstat()).
If path is absolute, then dirfd is ignored.
flags can either be 0, or include one or more of the following flags
ORed:
AT_EMPTY_PATH (since Linux 2.6.39)
If path is an empty string (or NULL, since Linux 6.11) operate on
the file referred to by dirfd (which may have been obtained using
the open(2)O_PATH flag). In this case, dirfd can refer to any
type of file, not just a directory, and the behavior of fstatat()
is similar to that of fstat(). If dirfd is AT_FDCWD, the call
operates on the current working directory. This flag is Linux-
specific; define _GNU_SOURCE to obtain its definition.
AT_NO_AUTOMOUNT (since Linux 2.6.38)
Don't automount the terminal ("basename") component of path.
Since Linux 3.1 this flag is ignored. Since Linux 4.11 this flag
is implied.
AT_SYMLINK_NOFOLLOW
If path is a symbolic link, do not dereference it: instead return
information about the link itself, like lstat(). (By default,
fstatat() dereferences symbolic links, like stat().)
See openat(2) for an explanation of the need for fstatat().
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set
to indicate the error.
ERRORSEACCES Search permission is denied for one of the directories in the path
prefix of path. (See also path_resolution(7).)
EBADF fd is not a valid open file descriptor.
EBADF (fstatat()) path is relative but dirfd is neither AT_FDCWD nor a
valid file descriptor.
EFAULT Bad address.
EINVAL (fstatat()) Invalid flag specified in flags.
ELOOP Too many symbolic links encountered while traversing the path.
ENAMETOOLONGpath is too long.
ENOENT A component of path does not exist or is a dangling symbolic link.
ENOENT path is an empty string and AT_EMPTY_PATH was not specified in
flags.
ENOMEM Out of memory (i.e., kernel memory).
ENOTDIR
A component of the path prefix of path is not a directory.
ENOTDIR
(fstatat()) path is relative and dirfd is a file descriptor
referring to a file other than a directory.
EOVERFLOWpath or fd refers to a file whose size, inode number, or number of
blocks cannot be represented in, respectively, the types off_t,
ino_t, or blkcnt_t. This error can occur when, for example, an
application compiled on a 32-bit platform without
-D_FILE_OFFSET_BITS=64 calls stat() on a file whose size exceeds
(1<<31)-1 bytes.
STANDARDS
POSIX.1-2024.
HISTORYstat()
fstat()
lstat()
SVr4, 4.3BSD, POSIX.1-2001.
fstatat()
POSIX.1-2008. Linux 2.6.16, glibc 2.4.
According to POSIX.1-2001, lstat() on a symbolic link need return valid
information only in the st_size field and the file type of the st_mode
field of the stat structure. POSIX.1-2008 tightens the specification,
requiring lstat() to return valid information in all fields except the
mode bits in st_mode.
Use of the st_blocks and st_blksize fields may be less portable. (They
were introduced in BSD. The interpretation differs between systems, and
possibly on a single system when NFS mounts are involved.)
C library/kernel differences
Over time, increases in the size of the stat structure have led to three
successive versions of stat(): sys_stat() (slot __NR_oldstat),
sys_newstat() (slot __NR_stat), and sys_stat64() (slot __NR_stat64) on
32-bit platforms such as i386. The first two versions were already
present in Linux 1.0 (albeit with different names); the last was added in
Linux 2.4. Similar remarks apply for fstat() and lstat().
The kernel-internal versions of the stat structure dealt with by the
different versions are, respectively:
__old_kernel_stat
The original structure, with rather narrow fields, and no padding.
stat Larger st_ino field and padding added to various parts of the
structure to allow for future expansion.
stat64 Even larger st_ino field, larger st_uid and st_gid fields to
accommodate the Linux-2.4 expansion of UIDs and GIDs to 32 bits,
and various other enlarged fields and further padding in the
structure. (Various padding bytes were eventually consumed in
Linux 2.6, with the advent of 32-bit device IDs and nanosecond
components for the timestamp fields.)
The glibc stat() wrapper function hides these details from applications,
invoking the most recent version of the system call provided by the
kernel, and repacking the returned information if required for old
binaries.
On modern 64-bit systems, life is simpler: there is a single stat()
system call and the kernel deals with a stat structure that contains
fields of a sufficient size.
The underlying system call employed by the glibc fstatat() wrapper
function is actually called fstatat64() or, on some architectures,
newfstatat().
EXAMPLES
The following program calls lstat() and displays selected fields in the
returned stat structure.
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <time.h>
int
main(int argc, char *argv[])
{
struct stat sb;
if (argc != 2) {
fprintf(stderr, "Usage: %s <path>\n", argv[0]);
exit(EXIT_FAILURE);
}
if (lstat(argv[1], &sb) == -1) {
perror("lstat");
exit(EXIT_FAILURE);
}
printf("ID of containing device: [%x,%x]\n",
major(sb.st_dev),
minor(sb.st_dev));
printf("File type: ");
switch (sb.st_mode & S_IFMT) {
case S_IFBLK: printf("block device\n"); break;
case S_IFCHR: printf("character device\n"); break;
case S_IFDIR: printf("directory\n"); break;
case S_IFIFO: printf("FIFO/pipe\n"); break;
case S_IFLNK: printf("symlink\n"); break;
case S_IFREG: printf("regular file\n"); break;
case S_IFSOCK: printf("socket\n"); break;
default: printf("unknown?\n"); break;
}
printf("I-node number: %ju\n", (uintmax_t) sb.st_ino);
printf("Mode: %jo (octal)\n",
(uintmax_t) sb.st_mode);
printf("Link count: %ju\n", (uintmax_t) sb.st_nlink);
printf("Ownership: UID=%ju GID=%ju\n",
(uintmax_t) sb.st_uid, (uintmax_t) sb.st_gid);
printf("Preferred I/O block size: %jd bytes\n",
(intmax_t) sb.st_blksize);
printf("File size: %jd bytes\n",
(intmax_t) sb.st_size);
printf("Blocks allocated: %jd\n",
(intmax_t) sb.st_blocks);
printf("Last status change: %s", ctime(&sb.st_ctime));
printf("Last file access: %s", ctime(&sb.st_atime));
printf("Last file modification: %s", ctime(&sb.st_mtime));
exit(EXIT_SUCCESS);
}
SEE ALSOls(1), stat(1), access(2), chmod(2), chown(2), readlink(2), statx(2),
utime(2), stat(3type), capabilities(7), inode(7), symlink(7)
Linux man-pages 6.16 2025-10-29 stat(2)