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STAT(2)                             Linux Programmer's Manual                             STAT(2)

       stat, fstat, lstat - get file status

       #include <sys/types.h>
       #include <sys/stat.h>
       #include <unistd.h>

       int stat(const char *path, struct stat *buf);
       int fstat(int fd, struct stat *buf);
       int lstat(const char *path, struct stat *buf);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L

       These  functions return information about a file.  No permissions are required on the file
       itself, but--in the case of stat() and lstat() -- execute (search) permission is  required
       on all of the directories in path that lead to the file.

       stat() stats the file pointed to by path and fills in buf.

       lstat()  is  identical  to  stat(),  except that if path is a symbolic link, then the link
       itself is stat-ed, not the file that it refers to.

       fstat() is identical to stat(), except that the file to be stat-ed  is  specified  by  the
       file descriptor fd.

       All of these system calls return a stat structure, which contains the following fields:

           struct stat {
               dev_t     st_dev;     /* ID of device containing file */
               ino_t     st_ino;     /* inode number */
               mode_t    st_mode;    /* protection */
               nlink_t   st_nlink;   /* number of hard links */
               uid_t     st_uid;     /* user ID of owner */
               gid_t     st_gid;     /* group ID of owner */
               dev_t     st_rdev;    /* device ID (if special file) */
               off_t     st_size;    /* total size, in bytes */
               blksize_t st_blksize; /* blocksize for file system I/O */
               blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
               time_t    st_atime;   /* time of last access */
               time_t    st_mtime;   /* time of last modification */
               time_t    st_ctime;   /* time of last status change */

       The  st_dev  field  describes  the  device  on which this file resides.  (The major(3) and
       minor(3) macros may be useful to decompose the device ID in this field.)

       The st_rdev field describes the device that this file (inode) represents.

       The st_size field gives the size of the file (if it is a regular file or a symbolic  link)
       in  bytes.  The size of a symbolic link is the length of the pathname it contains, without
       a terminating null byte.

       The st_blocks field indicates the number of blocks allocated to the file, 512-byte  units.
       (This may be smaller than st_size/512 when the file has holes.)

       The  st_blksize  field  gives  the  "preferred"  blocksize  for efficient file system I/O.
       (Writing to a file in smaller chunks may cause an inefficient read-modify-rewrite.)

       Not all of the Linux file systems implement all of the  time  fields.   Some  file  system
       types  allow  mounting  in  such a way that file and/or directory accesses do not cause an
       update of the st_atime field.  (See noatime, nodiratime, and  relatime  in  mount(8),  and
       related  information  in  mount(2).)   In  addition,  st_atime is not updated if a file is
       opened with the O_NOATIME; see open(2).

       The field st_atime is changed by file  accesses,  for  example,  by  execve(2),  mknod(2),
       pipe(2),  utime(2)  and  read(2) (of more than zero bytes).  Other routines, like mmap(2),
       may or may not update st_atime.

       The field st_mtime is changed by file  modifications,  for  example,  by  mknod(2),  trun-
       cate(2),  utime(2) and write(2) (of more than zero bytes).  Moreover, st_mtime of a direc-
       tory is changed by the creation or deletion of files  in  that  directory.   The  st_mtime
       field is not changed for changes in owner, group, hard link count, or mode.

       The  field  st_ctime  is  changed by writing or by setting inode information (i.e., owner,
       group, link count, mode, etc.).

       The following POSIX macros are defined to check the file type using the st_mode field:

           S_ISREG(m)  is it a regular file?

           S_ISDIR(m)  directory?

           S_ISCHR(m)  character device?

           S_ISBLK(m)  block device?

           S_ISFIFO(m) FIFO (named pipe)?

           S_ISLNK(m)  symbolic link?  (Not in POSIX.1-1996.)

           S_ISSOCK(m) socket?  (Not in POSIX.1-1996.)

       The following flags are defined for the st_mode field:

           S_IFMT     0170000   bit mask for the file type bit fields
           S_IFSOCK   0140000   socket
           S_IFLNK    0120000   symbolic link
           S_IFREG    0100000   regular file
           S_IFBLK    0060000   block device
           S_IFDIR    0040000   directory
           S_IFCHR    0020000   character device
           S_IFIFO    0010000   FIFO
           S_ISUID    0004000   set-user-ID bit
           S_ISGID    0002000   set-group-ID bit (see below)
           S_ISVTX    0001000   sticky bit (see below)
           S_IRWXU    00700     mask for file owner permissions
           S_IRUSR    00400     owner has read permission
           S_IWUSR    00200     owner has write permission
           S_IXUSR    00100     owner has execute permission
           S_IRWXG    00070     mask for group permissions
           S_IRGRP    00040     group has read permission
           S_IWGRP    00020     group has write permission
           S_IXGRP    00010     group has execute permission
           S_IRWXO    00007     mask for permissions for others (not in group)
           S_IROTH    00004     others have read permission
           S_IWOTH    00002     others have write permission
           S_IXOTH    00001     others have execute permission

       The set-group-ID bit (S_ISGID) has several special uses.  For  a  directory  it  indicates
       that  BSD  semantics  is  to be used for that directory: files created there inherit their
       group ID from the directory, not from the effective group ID of the creating process,  and
       directories  created  there  will  also get the S_ISGID bit set.  For a file that does not
       have the group execution bit (S_IXGRP)  set,  the  set-group-ID  bit  indicates  mandatory
       file/record locking.

       The sticky bit (S_ISVTX) on a directory means that a file in that directory can be renamed
       or deleted only by the owner of the file, by the owner of the directory, and by  a  privi-
       leged process.

       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.

       EACCES Search  permission is denied for one of the directories in the path prefix of path.
              (See also path_resolution(7).)

       EBADF  fd is bad.

       EFAULT Bad address.

       ELOOP  Too many symbolic links encountered while traversing the path.

              path is too long.

       ENOENT A component of path does not exist, or path is an empty string.

       ENOMEM Out of memory (i.e., kernel memory).

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

              path 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.

       These system calls conform to SVr4, 4.3BSD, POSIX.1-2001.

       According  to  POSIX.1-2001, lstat() on a symbolic link need return valid information only
       in the st_size field and the file-type component of the st_mode field of the  stat  struc-
       ture.   POSIX.-2008 tightens the specification, requiring lstat() to return valid informa-
       tion in all fields except the permission 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.)  If you need to obtain the definition of the blkcnt_t  or  blksize_t
       types  from  <sys/stat.h>, then define _XOPEN_SOURCE with the value 500 or greater (before
       including any header files).

       POSIX.1-1990 did not describe the S_IFMT, S_IFSOCK, S_IFLNK,  S_IFREG,  S_IFBLK,  S_IFDIR,
       S_IFCHR, S_IFIFO, S_ISVTX constants, but instead demanded the use of the macros S_ISDIR(),
       etc.  The S_IF* constants are present in POSIX.1-2001 and later.

       The S_ISLNK() and S_ISSOCK() macros are not in  POSIX.1-1996,  but  both  are  present  in
       POSIX.1-2001; the former is from SVID 4, the latter from SUSv2.

       UNIX  V7  (and  later  systems) had S_IREAD, S_IWRITE, S_IEXEC, where POSIX prescribes the
       synonyms S_IRUSR, S_IWUSR, S_IXUSR.

   Other systems
       Values that have been (or are) in use on various systems:

       hex    name       ls   octal    description
       f000   S_IFMT          170000   mask for file type

       0000                   000000   SCO out-of-service inode; BSD
                                       unknown type; SVID-v2 and XPG2 have
                                       both 0 and 0100000 for ordinary file
       1000   S_IFIFO    p|   010000   FIFO (named pipe)
       2000   S_IFCHR    c    020000   character special (V7)
       3000   S_IFMPC         030000   multiplexed character special (V7)
       4000   S_IFDIR    d/   040000   directory (V7)
       5000   S_IFNAM         050000   XENIX named special file with two
                                       subtypes, distinguished by st_rdev
                                       values 1, 2
       0001   S_INSEM    s    000001   XENIX semaphore subtype of IFNAM
       0002   S_INSHD    m    000002   XENIX shared data subtype of IFNAM
       6000   S_IFBLK    b    060000   block special (V7)
       7000   S_IFMPB         070000   multiplexed block special (V7)
       8000   S_IFREG    -    100000   regular (V7)
       9000   S_IFCMP         110000   VxFS compressed
       9000   S_IFNWK    n    110000   network special (HP-UX)
       a000   S_IFLNK    l@   120000   symbolic link (BSD)
       b000   S_IFSHAD        130000   Solaris shadow inode for ACL (not
                                       seen by user space)
       c000   S_IFSOCK   s=   140000   socket (BSD; also "S_IFSOC" on VxFS)
       d000   S_IFDOOR   D>   150000   Solaris door
       e000   S_IFWHT    w%   160000   BSD whiteout (not used for inode)
       0200   S_ISVTX         001000   sticky bit: save swapped text even
                                       after use (V7)
                                       reserved (SVID-v2)
                                       On nondirectories: don't cache this
                                       file (SunOS)
                                       On directories: restricted deletion
                                       flag (SVID-v4.2)
       0400   S_ISGID         002000   set-group-ID on execution (V7)
                                       for directories: use BSD semantics
                                       for propagation of GID
       0400   S_ENFMT         002000   System V file locking enforcement
                                       (shared with S_ISGID)
       0800   S_ISUID         004000   set-user-ID on execution (V7)
       0800   S_CDF           004000   directory is a context dependent
                                       file (HP-UX)

       A sticky command appeared in Version 32V AT&T UNIX.

       Since  kernel 2.5.48, the stat structure supports nanosecond resolution for the three file
       timestamp fields.  Glibc exposes the nanosecond component of each field using names of the
       form  st_atim.tv_nsec  if  the  _BSD_SOURCE or _SVID_SOURCE feature test macro is defined.
       These fields are specified in POSIX.1-2008, and, starting with version  2.12,  glibc  also
       exposes these field names if _POSIX_C_SOURCE is defined with the value 200809L or greater,
       or _XOPEN_SOURCE is defined with the value 700 or greater.  If none of the  aforementioned
       macros  are defined, then the nanosecond values are exposed with names of the form st_ati-
       mensec.  On file systems that do not support subsecond timestamps, the  nanosecond  fields
       are returned with the value 0.

       On  Linux, lstat() will generally not trigger automounter action, whereas stat() will (but
       see fstatat(2)).

       For most files under the /proc directory, stat() does not return  the  file  size  in  the
       st_size field; instead the field is returned with the value 0.

   Underlying kernel interface
       Over  time,  increases in the size of the stat structure have led to three successive ver-
       sions of stat(): sys_stat()  (slot  __NR_oldstat),  sys_newstat()  (slot  __NR_stat),  and
       sys_stat64()  (new  in  kernel  2.4; slot __NR_stat64).  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 bina-
       ries.  Similar remarks apply for fstat() and lstat().

       The following program calls stat() and displays  selected  fields  in  the  returned  stat

       #include <sys/types.h>
       #include <sys/stat.h>
       #include <time.h>
       #include <stdio.h>
       #include <stdlib.h>

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

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

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

           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:            %ld\n", (long) sb.st_ino);

           printf("Mode:                     %lo (octal)\n",
                   (unsigned long) sb.st_mode);

           printf("Link count:               %ld\n", (long) sb.st_nlink);
           printf("Ownership:                UID=%ld   GID=%ld\n",
                   (long) sb.st_uid, (long) sb.st_gid);

           printf("Preferred I/O block size: %ld bytes\n",
                   (long) sb.st_blksize);
           printf("File size:                %lld bytes\n",
                   (long long) sb.st_size);
           printf("Blocks allocated:         %lld\n",
                   (long long) 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));


       access(2),  chmod(2),  chown(2),  fstatat(2), readlink(2), utime(2), capabilities(7), sym-

       This page is part of release 3.53 of the Linux man-pages project.  A  description  of  the
       project,     and    information    about    reporting    bugs,    can    be    found    at

Linux                                       2012-11-11                                    STAT(2)

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