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STAT(2)                    Linux Programmer's ManualSTAT(2)NAME       stat, fstat, lstat, fstatat - get file statusSYNOPSIS       #include <sys/types.h>       #include <sys/stat.h>       #include <unistd.h>       int stat(const char *pathname, struct stat *statbuf);       int fstat(int fd, struct stat *statbuf);       int lstat(const char *pathname, struct stat *statbuf);       #include <fcntl.h>           /* Definition of AT_* constants */       #include <sys/stat.h>       int fstatat(int dirfd, const char *pathname, struct stat *statbuf,                   int flags);   Feature Test Macro Requirements for glibc (seefeature_test_macros(7)):       lstat():           /* glibc 2.19 and earlier */ _BSD_SOURCE               || /* Since glibc 2.20 */ _DEFAULT_SOURCE               || _XOPEN_SOURCE >= 500               || /* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200112L       fstatat():           Since glibc 2.10:               _POSIX_C_SOURCE >= 200809L           Before glibc 2.10:               _ATFILE_SOURCEDESCRIPTION       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 it refers to.       fstat() is identical to stat(), except that the file about which infor-       mation is to be retrieved is specified by the file descriptor fd.   The stat structure       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;        /* File type and mode */               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;     /* Block size for filesystem I/O */               blkcnt_t  st_blocks;      /* Number of 512B blocks allocated */               /* Since Linux 2.6, the kernel supports nanosecond                  precision for the following timestamp fields.                  For the details before Linux 2.6, see NOTES. */               struct timespec st_atim;  /* Time of last access */               struct timespec st_mtim;  /* Time of last modification */               struct timespec st_ctim;  /* Time of last status change */           #define st_atime st_atim.tv_sec      /* Backward compatibility */           #define st_mtime st_mtim.tv_sec           #define st_ctime st_ctim.tv_sec           };       Note: the order of fields in the stat structure varies somewhat  across       architectures.   In  addition,  the  definition above does not show the       padding bytes that may be present between some fields on various archi-       tectures.  Consult the glibc and kernel source code if you need to know       the details.       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 callingchmod(2) orchown(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 fields in the stat structure are as follows:       st_dev This  field  describes  the  device  on which this file resides.              (Themajor(3) andminor(3) macros may be useful to decompose the              device ID in this field.)       st_ino This field contains the file's inode number.       st_mode              This  field  contains  the file type and mode.  Seeinode(7) for              further information.       st_nlink              This field contains the number of hard links to the file.       st_uid This field contains the user ID of the owner of the file.       st_gid This field contains the ID of the group owner of the file.       st_rdev              This field describes the device that this  file  (inode)  repre-              sents.       st_size              This  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.       st_blksize              This field  gives  the  "preferred"  block  size  for  efficient              filesystem I/O.       st_blocks              This field indicates the number of blocks allocated to the file,              in 512-byte units.  (This may be smaller than  st_size/512  when              the file has holes.)       st_atime              This is the file's last access timestamp.       st_mtime              This is the file's last modification timestamp.       st_ctime              This is the file's last status change timestamp.       For further information on the above fields, seeinode(7).   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, operate on the file referred to              by dirfd (which may have been obtained using theopen(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              if it is a directory that is an automount  point.   This  allows              the  caller  to  gather attributes of an automount point (rather              than the location it would mount).  Since Linux 4.14, also don't              instantiate a nonexistent name in an on-demand directory such as              used for automounter indirect maps.  This flag can  be  used  in              tools  that  scan  directories to prevent mass-automounting of a              directory of automount points.  The AT_NO_AUTOMOUNT flag has  no              effect  if  the mount point has already been mounted over.  This              flag is Linux-specific; define _GNU_SOURCE to obtain its defini-              tion.  Both stat() and lstat() act as though AT_NO_AUTOMOUNT was              set.       AT_SYMLINK_NOFOLLOW              If pathname is a symbolic link, do not dereference  it:  instead              return information about the link itself, like lstat().  (By de-              fault, fstatat() dereferences symbolic links, like stat().)       Seeopenat(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 appropriately.ERRORS       EACCES Search  permission  is  denied for one of the directories in the              path prefix of pathname.  (See alsopath_resolution(7).)       EBADF  fd is not a valid open file descriptor.       EFAULT Bad address.       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.       EOVERFLOW              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.       The following additional errors can occur for fstatat():       EBADF  dirfd is not a valid file descriptor.       EINVAL Invalid flag specified in flags.       ENOTDIR              pathname is relative and dirfd is a file descriptor referring to              a file other than a directory.VERSIONS       fstatat() was added to Linux in  kernel  2.6.16;  library  support  was       added to glibc in version 2.4.CONFORMING TO       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.)NOTES   Timestamp fields       Older  kernels and older standards did not support nanosecond timestamp       fields.   Instead,  there  were   three   timestamp   fields--st_atime,       st_mtime,  and  st_ctime--typed as time_t that recorded timestamps with       one-second precision.       Since kernel 2.5.48, the stat structure supports nanosecond  resolution       for the three file timestamp fields.  The nanosecond components of each       timestamp are available via names of the form st_atim.tv_nsec, if suit-       able feature test macros are defined.  Nanosecond timestamps were stan-       dardized in POSIX.1-2008, and, starting with version  2.12,  glibc  ex-       poses the nanosecond component names if _POSIX_C_SOURCE is defined with       the value 200809L or greater, or  _XOPEN_SOURCE  is  defined  with  the       value  700 or greater.  Up to and including glibc 2.19, the definitions       of the nanoseconds  components  are  also  defined  if  _BSD_SOURCE  or       _SVID_SOURCE  is defined.  If none of the aforementioned macros are de-       fined, then the nanosecond values are exposed with names  of  the  form       st_atimensec.   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 pad-              ding.       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 ac-              commodate 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  applica-       tions,  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().EXAMPLE       The following program calls lstat() 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>       #include <sys/sysmacros.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:  [%lx,%lx]\n",                (long) major(sb.st_dev), (long) 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:            %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 ALSOls(1),stat(1),access(2),chmod(2),chown(2),readlink(2),statx(2),utime(2),capabilities(7),inode(7),symlink(7)COLOPHON       This  page  is  part of release 5.05 of the Linux man-pages project.  A       description of the project, information about reporting bugs,  and  the       latest     version     of     this    page,    can    be    found    at       https://www.kernel.org/doc/man-pages/.Linux                             2019-03-06STAT(2)