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STAT(2)                          System calls                          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 *file_name, struct stat *buf);
       int fstat(int filedes, struct stat *buf);
       int lstat(const char *file_name, struct stat *buf);

DESCRIPTION
       These functions return information about the specified file.  You do
       not need any access rights to the file to get this information but you
       need search rights to all directories named in the path leading to the
       file.

       stat stats the file pointed to by file_name and fills in buf.

       lstat is identical to stat, except in the case of a symbolic link,
       where the link itself is stat-ed, not the file that it refers to.

       fstat is identical to stat, only the open file pointed to by filedes
       (as returned by open(2)) is stat-ed in place of file_name.

       They all return a stat structure, which contains the following fields:

              struct stat {
                  dev_t         st_dev;      /* device */
                  ino_t         st_ino;      /* inode */
                  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 type (if inode device) */
                  off_t         st_size;     /* total size, in bytes */
                  blksize_t     st_blksize;  /* blocksize for filesystem I/O */
                  blkcnt_t      st_blocks;   /* number of 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 change */
              };

       The value st_size gives the size of the file (if it is a regular file
       or a symlink) in bytes. The size of a symlink is the length of the
       pathname it contains, without trailing NUL.

       The value st_blocks gives the size of the file in 512-byte blocks.
       (This may be smaller than st_size/512 e.g. when the file has holes.)
       The value st_blksize 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 filesystems implement all of the time fields.
       Some file system types allow mounting in such a way that file accesses
       do not cause an update of the st_atime field. (See `noatime' in
       mount(8).)

       The field st_atime is changed by file accesses, e.g. 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, e.g. 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
       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:

              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?

              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   bitmask for the file type bitfields
       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 UID bit
       S_ISGID    0002000   set GID 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 permisson
       S_IXOTH    00001     others have execute permission

       The set GID 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 gid 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, it 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 root.

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

ERRORS
       EBADF  filedes is bad.

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

       ENOTDIR
              A component of the path is not a directory.

       ELOOP  Too many symbolic links encountered while traversing the path.

       EFAULT Bad address.

       EACCES Permission denied.

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

       ENAMETOOLONG
              File name too long.

CONFORMING TO
       The stat and fstat calls conform to SVr4, SVID, POSIX, X/OPEN, BSD 4.3.
       The lstat call conforms to 4.3BSD and SVr4.  SVr4 documents additional
       fstat error conditions EINTR, ENOLINK, and EOVERFLOW.  SVr4 documents
       additional stat and lstat error conditions EACCES, EINTR, EMULTIHOP,
       ENOLINK, and EOVERFLOW.  Use of the st_blocks and st_blksize fields may
       be less portable. (They were introduced in BSD.  Are not specified by
       POSIX. The interpretation differs between systems, and possibly on a
       single system when NFS mounts are involved.)

       POSIX does not describe the S_IFMT, S_IFSOCK, S_IFLNK, S_IFREG,
       S_IFBLK, S_IFDIR, S_IFCHR, S_IFIFO, S_ISVTX bits, but instead demands
       the use of the macros S_ISDIR(), etc. The S_ISLNK and S_ISSOCK macros
       are not in POSIX.1-1996, but both will be in the next POSIX standard;
       the former is from SVID 4v2, 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 userspace)
       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 non-directories: 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   SysV file locking enforcement (shared w/ 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.

SEE ALSO
       chmod(2), chown(2), readlink(2), utime(2)

Linux                             1998-05-13                           STAT(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | OTHER SYSTEMS | SEE ALSO

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