stat(2)                                                 System Calls Manual                                                 stat(2)

       stat, fstat, lstat, fstatat - get file status

       Standard C library (libc, -lc)

       #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)):

           /* Since glibc 2.20 */ _DEFAULT_SOURCE
               || _XOPEN_SOURCE >= 500
               || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L
               || /* glibc 2.19 and earlier */ _BSD_SOURCE

           Since glibc 2.10:
               _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:

       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  direc‐
       tories 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

       lstat() is identical to stat(), except that if pathname is a symbolic link, then it returns information about the  link  it‐
       self, 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 de‐
       scriptor 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 dif‐
       ferent  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.

       The fstatat() system call is a more general interface for accessing file information which can still provide exactly the be‐
       havior 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  de‐
       scriptor  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  work‐
       ing 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, 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 pathname.  Since Linux 3.1 this flag is ignored.  Since  Linux
              4.11 this flag is implied.

              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) for an explanation of the need for fstatat().

       On success, zero is returned.  On error, -1 is returned, and errno is set to indicate the error.

       EACCES Search permission is denied for one of the directories in the  path  prefix  of  pathname.   (See  also  path_resolu‐

       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.

              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).

              A component of the path prefix of pathname is not a directory.

              (fstatat()) pathname is relative and dirfd is a file descriptor referring to a file other than a directory.

              pathname 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.

       fstatat() was added in Linux 2.6.16; library support was added in glibc 2.4.

       stat(), fstat(), lstat(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1.2008.

       fstatat(): POSIX.1-2008.

       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.   Simi‐
       lar remarks apply for fstat() and lstat().

       The kernel-internal versions of the stat structure dealt with by the different versions are, respectively:

              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 eventu‐
              ally 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 ar‐
       chitectures, newfstatat().

       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>

       main(int argc, char *argv[])
           struct stat sb;

           if (argc != 2) {
               fprintf(stderr, "Usage: %s <pathname>\n", argv[0]);

           if (lstat(argv[1], &sb) == -1) {

           printf("ID of containing device:  [%x,%x]\n",

           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));


       ls(1), stat(1), access(2), chmod(2), chown(2), readlink(2), statx(2), utime(2), stat(3type), capabilities(7), inode(7), sym‐

Linux man-pages 6.03                                         2023-02-05                                                     stat(2)