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


NAME
     stat, lstat, fstat - get file status

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

     stat(path, buf)
     char *path;
     struct stat *buf;

     lstat(path, buf)
     char *path;
     struct stat *buf;

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

DESCRIPTION
     Stat obtains information about the file 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 reachable.

     Lstat is like stat except in the case where the named file
     is a symbolic link, in which case lstat returns information
     about the link, while stat returns information about the
     file the link references.

     Fstat obtains the same information about an open file refer-
     enced by the argument descriptor, such as would be obtained
     by an open call.

     Buf is a pointer to a stat structure into which information
     is placed concerning the file.  The contents of the struc-
     ture pointed to by buf

	  struct stat {
	       dev_t  st_dev; /* device inode resides on */
	       ino_t  st_ino; /* this inode's number */
	       u_short	      st_mode;/* protection */
	       short  st_nlink;/* number or hard links to the file */
	       short  st_uid; /* user-id of owner */
	       short  st_gid; /* group-id of owner */
	       dev_t  st_rdev;/* the device type, for inode that is device */
	       off_t  st_size;/* total size of file */
	       time_t st_atime;/* file last access time */
	       int    st_spare1;
	       time_t st_mtime;/* file last modify time */
	       int    st_spare2;
	       time_t st_ctime;/* file last status change time */


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


	       int    st_spare3;
	       long   st_blksize;/* optimal blocksize for file system i/o ops */
	       long   st_blocks;/* actual number of blocks allocated */
	       long   st_spare4[2];
	 };

     st_atime	 Time when file data was last read or modified.
		 Changed by the following system calls: mknod(2),
		 utimes(2), read(2), and write(2).  For reasons
		 of efficiency, st_atime is not set when a direc-
		 tory is searched, although this would be more
		 logical.

     st_mtime	 Time when data was last modified.  It is not set
		 by changes of owner, group, link count, or mode.
		 Changed by the following system calls: mknod(2),
		 utimes(2), write(2).

     st_ctime	 Time when file status was last changed.  It is
		 set both both by writing and changing the i-
		 node.	Changed by the following system calls:
		 chmod(2) chown(2), link(2), mknod(2), rename(2),
		 unlink(2), utimes(2), write(2).

     The status information word st_mode has bits:
	  #define S_IFMT  0170000  /* type of file */
	  #define    S_IFDIR	   0040000/* directory */
	  #define    S_IFCHR	   0020000/* character special */
	  #define    S_IFBLK	   0060000/* block special */
	  #define    S_IFREG	   0100000/* regular */
	  #define    S_IFLNK	   0120000/* symbolic link */
	  #define    S_IFSOCK	   0140000/* socket */
	  #define S_ISUID 0004000  /* set user id on execution */
	  #define S_ISGID 0002000  /* set group id on execution */
	  #define S_ISVTX 0001000  /* save swapped text even after use */
	  #define S_IREAD 0000400  /* read permission, owner */
	  #define S_IWRITE	   0000200/* write permission, owner */
	  #define S_IEXEC 0000100  /* execute/search permission, owner */

     The mode bits 0000070 and 0000007 encode group and others
     permissions (see chmod(2)).

RETURN VALUE
     Upon successful completion a value of 0 is returned.  Other-
     wise, a value of -1 is returned and errno is set to indicate
     the error.

ERRORS
     Stat and lstat will fail if one or more of the following are
     true:

     [ENOTDIR]	    A component of the path prefix is not a


Printed 11/26/99	  May 12, 1986				2


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


		    directory.

     [EINVAL]	    The pathname contains a character with the
		    high-order bit set.

     [ENAMETOOLONG] A component of a pathname exceeded 255 char-
		    acters, or an entire path name exceeded 1023
		    characters.

     [ENOENT]	    The named file does not exist.

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

     [ELOOP]	    Too many symbolic links were encountered in
		    translating the pathname.

     [EFAULT]	    Buf or name points to an invalid address.

     [EIO]	    An I/O error occurred while reading from or
		    writing to the file system.

     Fstat will fail if one or both of the following are true:

     [EBADF]	    Fildes is not a valid open file descriptor.

     [EFAULT]	    Buf points to an invalid address.

     [EIO]	    An I/O error occurred while reading from or
		    writing to the file system.

CAVEAT
     The fields in the stat structure currently marked st_spare1,
     st_spare2, and st_spare3 are present in preparation for
     inode time stamps expanding to 64 bits.  This, however, can
     break certain programs that depend on the time stamps being
     contiguous (in calls to utimes(2)).

SEE ALSO
     chmod(2), chown(2), utimes(2)

BUGS
     Applying fstat to a socket (and thus to a pipe) returns a
     zero'd buffer, except for the blocksize field, and a unique
     device and inode number.


Printed 11/26/99	  May 12, 1986				3


 
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