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

NAME
       stat, fstat, lstat - get	file status

SYNOPSIS
       #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)):

       lstat():
	   _BSD_SOURCE || _XOPEN_SOURCE	>= 500 ||
	   _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
	   || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L

DESCRIPTION
       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)	repre-
       sents.

       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  ineffi-
       cient 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  ex-
       ecve(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), truncate(2), utime(2) and write(2) (of	more than zero bytes).
       Moreover, st_mtime of a directory is changed by the creation  or	 dele-
       tion 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  informa-
       tion (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	direc-
       tory  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  di-
       rectory can be renamed or deleted only by the owner of the file,	by the
       owner of	the directory, and by a	privileged process.

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

ERRORS
       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.

       ENAMETOOLONG
	      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).

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

       EOVERFLOW
	      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 exam-
	      ple,  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.

CONFORMING TO
       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 structure.  POSIX.-2008 tightens the
       specification, requiring	lstat()	to return  valid  information  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 de-
       manded 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 un-
				       known 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.

NOTES
       Since  kernel 2.5.48, the stat structure	supports nanosecond resolution
       for the three file timestamp fields.  Glibc exposes the nanosecond com-
       ponent  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  de-
       fined,  then  the  nanosecond values are	exposed	with names of the form
       st_atimensec.  On file systems that  do	not  support  subsecond	 time-
       stamps, 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  versions  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 de-
       tails 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.   Similar  remarks  apply  for  fstat()  and
       lstat().

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

       #include	<sys/types.h>
       #include	<sys/stat.h>
       #include	<time.h>
       #include	<stdio.h>
       #include	<stdlib.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 (stat(argv[1], &sb) == -1) {
	       perror("stat");
	       exit(EXIT_FAILURE);
	   }

	   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));

	   exit(EXIT_SUCCESS);
       }

SEE ALSO
       access(2), chmod(2), chown(2), fstatat(2), readlink(2), utime(2), capa-
       bilities(7), symlink(7)

COLOPHON
       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 http://www.kernel.org/doc/man-pages/.

Linux				  2012-11-11			       STAT(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | EXAMPLE | SEE ALSO | COLOPHON

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