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fstat(2)

stat(2)                          System Calls                          stat(2)



NAME
       stat, lstat, fstat, fstatat - get file status

SYNOPSIS
       #include <fcntl.h>
       #include <sys/types.h>
       #include <sys/stat.h>

       int stat(const char *restrict path, struct stat *restrict buf);


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


       int fstat(int fildes, struct stat *buf);


       int fstatat(int fildes, const char *path, struct stat *buf,
            int flag);


DESCRIPTION
       The  stat()  function  obtains information about the file pointed to by
       path. Read, write, or execute permission  of  the  named  file  is  not
       required,  but  all  directories listed in the path name leading to the
       file must be searchable.


       The lstat() function obtains file attributes similar to stat(),  except
       when  the  named  file is a symbolic link; in that case lstat() returns
       information about the link, while stat() returns information about  the
       file the link references.


       The  fstat()  function  obtains information about an open file known by
       the  file  descriptor  fildes,  obtained  from  a  successful  open(2),
       creat(2), dup(2), fcntl(2), or pipe(2) function. If fildes references a
       shared memory object, the system updates in the stat structure  pointed
       to  by  the  buf argument only the st_uid, st_gid, st_size, and st_mode
       fields, and only the S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP,  S_IROTH,  and
       S_IWOTH file permission bits need be valid. The system can update other
       fields and flags. The fstat() function updates any pending time-related
       fields before writing to the stat structure.


       The  fstatat()  function obtains file attributes similar to the stat(),
       lstat(), and fstat() functions.  If the path  argument  is  a  relative
       path,  it  is  resolved relative to the fildes argument rather than the
       current working directory.  If path is absolute, the fildes argument is
       unused.   If  the fildes argument has the special value AT_FDCWD, rela‐
       tive paths are resolved from the current working directory. If  AT_SYM‐
       LINK_NOFOLLOW  is  set  in the flag argument, the function behaves like
       lstat()  and  does  not  automatically  follow  symbolic   links.   See
       fsattr(5). If _AT_TRIGGER is set in the  flag argument and the vnode is
       a trigger mount point, the mount is performed and the function  returns
       the attributes of the root of the mounted filesystem.


       The  buf  argument is a pointer to a stat structure into which informa‐
       tion is placed concerning the file. A stat structure includes the  fol‐
       lowing members:

         mode_t   st_mode;          /* File mode (see mknod(2)) */
         ino_t    st_ino;           /* File serial number */
         dev_t    st_dev;           /* ID of device containing */
                                    /* a directory entry for this file */
         dev_t    st_rdev;          /* ID of device */
                                    /* This entry is defined only for */
                                    /* char special or block special files */
         nlink_t  st_nlink;         /* Number of links */
         uid_t    st_uid;           /* User ID of the file's owner */
         gid_t    st_gid;           /* Group ID of the file's group */
         off_t    st_size;          /* File size in bytes */
         time_t   st_atime;         /* Time of last access */
         time_t   st_mtime;         /* Time of last data modification */
         time_t   st_ctime;         /* Time of last file status change */
                                    /* Times measured in seconds since */
                                    /* 00:00:00 UTC, Jan. 1, 1970 */
         long     st_blksize;       /* Preferred I/O block size */
         blkcnt_t st_blocks;        /* Number of 512 byte blocks allocated*/
         char     st_fstype[_ST_FSTYPSZ];
                                    /* Null-terminated type of filesystem */



       Descriptions of structure members are as follows:

       st_mode       The  mode  of the file as described for the mknod() func‐
                     tion. In addition to the modes described on the  mknod(2)
                     manual  page,  the mode of a file can also be S_IFSOCK if
                     the file is a socket, S_IFDOOR if the  file  is  a  door,
                     S_IFPORT  if the file is an event port, or S_IFLNK if the
                     file is a symbolic link. S_IFLNK can be  returned  either
                     by  lstat()  or  by  fstat() when the AT_SYMLINK_NOFOLLOW
                     flag is set.


       st_ino        This field uniquely identifies the file in a  given  file
                     system.  The pair  st_ino and  st_dev uniquely identifies
                     regular files.


       st_dev        This field uniquely identifies the file system that  con‐
                     tains  the  file.  Its  value may be used as input to the
                     ustat() function to determine more information about this
                     file  system.  No  other  meaning is associated with this
                     value.


       st_rdev       This field should be used  only  by  administrative  com‐
                     mands.  It  is  valid only for block special or character
                     special files and only has meaning on  the  system  where
                     the file was configured.


       st_nlink      This  field  should  be  used only by administrative com‐
                     mands.


       st_uid        The user ID of the file's owner.


       st_gid        The group ID of the file's group.


       st_size       For regular files, this is the address of the end of  the
                     file. For block special or character special, this is not
                     defined. See also pipe(2).


       st_atime      Time when file data was last accessed. Some of the  func‐
                     tions  that  change  this  member  are: creat(), mknod(),
                     pipe(), utime(2), and read(2).


       st_mtime      Time when data was last modified. Some of  the  functions
                     that  change  this  member are: creat(), mknod(), pipe(),
                     utime(), and write(2).


       st_ctime      Time when file status was last changed. Some of the func‐
                     tions  that  change  this member are: chmod(2), chown(2),
                     creat(2),   link(2),   mknod(2),   pipe(2),    rename(2),
                     unlink(2), utime(2), and write(2).


       st_blksize    A  hint  as  to  the "best" unit size for I/O operations.
                     This field is not defined for block special or  character
                     special files.


       st_blocks     The  total  number  of  physical blocks of size 512 bytes
                     actually allocated on disk. This field is not defined for
                     block special or character special files.


       st_fstype     A null-teminated string that uniquely identifies the type
                     of the filesystem that contains the file.


RETURN VALUES
       Upon successful completion, 0 is returned. Otherwise,  −1  is  returned
       and errno is set to indicate the error.

ERRORS
       The stat(), fstat(), lstat(), and fstatat() functions will fail if:

       EIO          An error occurred while reading from the file system.


       EOVERFLOW    The  file  size in bytes or the number of blocks allocated
                    to the file or the file serial  number  cannot  be  repre‐
                    sented correctly in the structure pointed to by buf.



       The stat(), lstat(), and fstatat() functions will fail if:

       EACCES          Search permission is denied for a component of the path
                       prefix.


       EFAULT          The  buf or path argument points to an illegal address.


       EINTR           A signal was caught during the execution of the  stat()
                       or lstat() function.


       ELOOP           A  loop exists in symbolic links encountered during the
                       resolution of the path argument.


       ENAMETOOLONG    The length of the path argument exceeds {PATH_MAX},  or
                       the length of a path component exceeds {NAME_MAX} while
                       _POSIX_NO_TRUNC is in effect.


       ENOENT          A component of path does not name an existing  file  or
                       path is an empty string.


       ENOLINK         The  path  argument  points to a remote machine and the
                       link to that machine is no longer active.


       ENOTDIR         A component of the path prefix is not a  directory,  or
                       the fildes argument does not refer to a valid directory
                       when given a non-null relative path.



       The fstat() and fstatat() functions will fail if:

       EBADF      The fildes argument is not a valid open file descriptor. The
                  fildes  argument  to fstatat() can also have the valid value
                  of AT_FDCWD.


       EFAULT     The buf argument points to an illegal address.


       EINTR      A signal was caught during  the  execution  of  the  fstat()
                  function.


       ENOLINK    The  fildes argument points to a remote machine and the link
                  to that machine is no longer active.



       The stat(), fstat(), and lstat() functions may fail if:

       EOVERFLOW    One of the members is too  large  to  store  in  the  stat
                    structure pointed to by buf.



       The stat() and lstat() functions may fail if:

       ELOOP           More than {SYMLOOP_MAX} symbolic links were encountered
                       during the resolution of the path argument.


       ENAMETOOLONG    As a result of encountering a symbolic link in  resolu‐
                       tion of thepath argument, the length of the substituted
                       pathname strings exceeds {PATH_MAX}.



       The stat() and fstatat() functions may fail if:

       ENXIO    The path argument names a character or  block  device  special
                file  and the corresponding I/O device has been retired by the
                fault management framework.


EXAMPLES
       Example 1 Use stat() to obtain file status information.


       The following example shows how to obtain file status information for a
       file named /home/cnd/mod1. The structure variable buffer is defined for
       the stat structure.


         #include <sys/types.h>
         #include <sys/stat.h>
         #include <fcntl.h>
         struct stat buffer;
         int         status;
         ...
         status = stat("/home/cnd/mod1", &buffer);


       Example 2 Use stat() to get directory information.


       The following example fragment gets status information for  each  entry
       in a directory. The call to the stat() function stores file information
       in the stat structure pointed to by statbuf. The lines that follow  the
       stat() call format the fields in the stat structure for presentation to
       the user of the program.


         #include <sys/types.h>
         #include <sys/stat.h>
         #include <dirent.h>
         #include <pwd.h>
         #include <grp.h>
         #include <time.h>
         #include <locale.h>
         #include <langinfo.h>
         #include <stdio.h>
         #include <stdint.h>
         struct dirent *dp;
         struct stat   statbuf;
         struct passwd *pwd;
         struct group  *grp;
         struct tm     *tm;
         char          datestring[256];
         ...
         /* Loop through directory entries */
         while ((dp = readdir(dir)) != NULL) {
             /* Get entry's information. */
             if (stat(dp->d_name, &statbuf) == -1)
             continue;

              /* Print out type, permissions, and number of links. */
              printf("%10.10s", sperm (statbuf.st_mode));
              printf("%4d", statbuf.st_nlink);

              /* Print out owners name if it is found using getpwuid(). */
              if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
                 printf(" %-8.8s", pwd->pw_name);
              else
                 printf(" %-8d", statbuf.st_uid);

              /* Print out group name if it's found using getgrgid(). */
              if ((grp = getgrgid(statbuf.st_gid)) != NULL)
                 printf(" %-8.8s", grp->gr_name);
              else
                 printf(" %-8d", statbuf.st_gid);

              /* Print size of file. */
              printf(" %9jd", (intmax_t)statbuf.st_size);
              tm = localtime(&statbuf.st_mtime);

              /* Get localized date string. */
              strftime(datestring, sizeof(datestring), nl_langinfo(D_T_FMT), tm);

              printf(" %s %s\n", datestring, dp->d_name);
          }


       Example 3 Use fstat() to obtain file status information.


       The following example shows how to obtain file status information for a
       file named /home/cnd/mod1. The structure variable buffer is defined for
       the stat structure. The /home/cnd/mod1 file is opened  with  read/write
       privileges and is passed to the open file descriptor fildes.


         #include <sys/types.h>
         #include <sys/stat.h>
         #include <fcntl.h>
         struct stat buffer;
         int         status;
         ...
         fildes = open("/home/cnd/mod1", O_RDWR);
         status = fstat(fildes, &buffer);


       Example 4 Use lstat() to obtain symbolic link status information.


       The following example shows how to obtain status information for a sym‐
       bolic link named  /modules/pass1.  The  structure  variable  buffer  is
       defined  for  the  stat  structure.  If the path argument specified the
       filename for the file pointed to by the symbolic link (/home/cnd/mod1),
       the results of calling the function would be the same as those returned
       by a call to the stat() function.


         #include <sys/stat.h>
         struct stat buffer;
         int         status;
         ...
         status = lstat("/modules/pass1", &buffer);


USAGE
       If chmod() or fchmod() is used to change the file group  owner  permis‐
       sions  on a file with non-trivial ACL entries, only the ACL mask is set
       to the new permissions and the  group  owner  permission  bits  in  the
       file's  mode  field (defined in mknod(2)) are unchanged.  A non-trivial
       ACL entry is one whose meaning cannot be represented in the file's mode
       field  alone.  The new ACL mask permissions  might change the effective
       permissions for additional users and groups that have  ACL  entries  on
       the file.


       The stat(), fstat(), and lstat() functions have transitional interfaces
       for 64-bit file offsets.  See lf64(5).

ATTRIBUTES
       See attributes(5) for descriptions of the following attributes:




       tab()  box;  cw(2.75i)  |cw(2.75i)  lw(2.75i)   |lw(2.75i)   ATTRIBUTE
       TYPEATTRIBUTE  VALUE _ Interface StabilityCommitted _ MT-LevelAsync-
       Signal-Safe _ Standard See below.



       For stat(), fstat(), and lstat(), see standards(5).

SEE ALSO
       access(2), chmod(2), chown(2), creat(2),  link(2),  mknod(2),  pipe(2),
       read(2),   time(2),   unlink(2),   utime(2),   write(2),   fattach(3C),
       stat.h(3HEAD), attributes(5), fsattr(5), lf64(5), standards(5)



SunOS 5.11                        25 Mar 2015                          stat(2)
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