stat(2) - Linux manual page (original) (raw)
stat(2) System Calls Manual stat(2)
NAME top
stat, fstat, lstat, fstatat - get file statusLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#include <sys/stat.h>**
**int stat(const char *restrict** _pathname_**,**
**struct stat *restrict** _statbuf_**);**
**int fstat(int** _fd_**, struct stat ***_statbuf_**);**
**int lstat(const char *restrict** _pathname_**,**
**struct stat *restrict** _statbuf_**);**
**#include <fcntl.h>** /* Definition of **AT_*** constants */
**#include <sys/stat.h>**
**int fstatat(int** _dirfd_**, const char *restrict** _pathname_**,**
**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_SOURCEDESCRIPTION top
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
_pathname_ that lead to the file.
**stat**() and **fstatat**() retrieve information about the file pointed
to by _pathname_; the differences for **fstatat**() are described below.
**lstat**() is identical to **stat**(), except that if _pathname_ 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
_stmode_ or _stuid_ is changed by another process by calling
[chmod(2)](../man2/chmod.2.html) or [chown(2)](../man2/chown.2.html), **stat**() might return the old _stmode_ together
with the new _stuid_, or the old _stuid_ together with the new
_stmode_.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 the pathname given in _pathname_ 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 _pathname_ is relative and _dirfd_ is the special value **AT_FDCWD**,
then _pathname_ is interpreted relative to the current working
directory of the calling process (like **stat**() and **lstat**()).
If _pathname_ 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 _pathname_ 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)](../man2/open.2.html) **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
_pathname._ Since Linux 3.1 this flag is ignored. Since
Linux 4.11 this flag is implied.
**AT_SYMLINK_NOFOLLOW**
If _pathname_ 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)](../man2/openat.2.html) for an explanation of the need for **fstatat**().RETURN VALUE top
On success, zero is returned. On error, -1 is returned, and _[errno](../man3/errno.3.html)_
is set to indicate the error.ERRORS top
**EACCES** Search permission is denied for one of the directories in
the path prefix of _pathname_. (See also
[path_resolution(7)](../man7/path%5Fresolution.7.html).)
**EBADF** _fd_ is not a valid open file descriptor.
**EBADF** (**fstatat**()) _pathname_ 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.
**ENAMETOOLONG**
_pathname_ is too long.
**ENOENT** A component of _pathname_ does not exist or is a dangling
symbolic link.
**ENOENT** _pathname_ 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 _pathname_ is not a
directory.
**ENOTDIR**
(**fstatat**()) _pathname_ is relative and _dirfd_ is a file
descriptor referring to a file other than a directory.
**EOVERFLOW**
_pathname_ or _fd_ refers to a file whose size, inode number,
or number of blocks cannot be represented in, respectively,
the types _offt_, _inot_, or _blkcntt_. This error can occur
when, for example, an application compiled on a 32-bit
platform without _-DFILEOFFSETBITS=64_ calls **stat**() on a
file whose size exceeds _(1<<31)-1_ bytes.STANDARDS top
POSIX.1-2008.HISTORY top
**stat**()
**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 _stsize_ field and the file type of
the _stmode_ 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 _stmode_.
Use of the _stblocks_ and _stblksize_ 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(): sysstat() (slot _NRoldstat), sysnewstat() (slot _NRstat), and sysstat64() (slot _NRstat64) 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:
__oldkernelstat_
The original structure, with rather narrow fields, and no
padding.
_stat_ Larger _stino_ field and padding added to various parts of
the structure to allow for future expansion.
_stat64_ Even larger _stino_ field, larger _stuid_ and _stgid_ 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 top
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 <pathname>\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 ALSO top
[ls(1)](../man1/ls.1.html), [stat(1)](../man1/stat.1.html), [access(2)](../man2/access.2.html), [chmod(2)](../man2/chmod.2.html), [chown(2)](../man2/chown.2.html), [readlink(2)](../man2/readlink.2.html),
[statx(2)](../man2/statx.2.html), [utime(2)](../man2/utime.2.html), [stat(3type)](../man3/stat.3type.html), [capabilities(7)](../man7/capabilities.7.html), [inode(7)](../man7/inode.7.html),
[symlink(7)](../man7/symlink.7.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.10 2025-01-09 stat(2)
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