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stat

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 refer-
     ences.


     The fstat() function obtains information about an open  file
     known  by  the  file descriptor fildes, obtained from a suc-
     cessful 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()  func-
     tion  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, relative
     paths are resolved from the current  working  directory.  If
     AT_SYMLINK_NOFOLLOW  is  set in the flag argument, the func-
     tion 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
     information  is placed concerning the file. A stat structure
     includes the following 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()  function.  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  contains 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  administra-
                   tive commands. It is valid only for block spe-
                   cial or character special files and  only  has
                   meaning  on the system where the file was con-
                   figured.


     st_nlink
                   This field should be used only by  administra-
                   tive commands.


     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 charac-
                   ter special, this is  not  defined.  See  also
                   pipe(2).


     st_atime
                   Time when file data was last accessed. Some of
                   the  functions  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 functions 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  identi-
                   fies  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 represented correctly in  the  struc-
                  ture 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 ille-
                     gal 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 com-
                     ponent     exceeds     {NAME_MAX}      while
                     _POSIX_NO_TRUNC is in effect.


     ENOENT
                     A component of path does not name an  exist-
                     ing 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   resolution  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 infor-
     mation  for a file named /home/cnd/mod1. The structure vari-
     able 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 infor-
     mation  for a file named /home/cnd/mod1. The structure vari-
     able  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  infor-
     mation.


     The following example shows how to obtain status information
     for  a  symbolic  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  cal-
     ling  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  permissions  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  attri-
     butes:



     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)
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