STAT(2) BSD 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 pathname 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 referenced 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 structure pointed to by buf is
as follows:
struct stat
{
dev_t st_dev; /* device inode resides on */
ino_t st_ino; /* this inode's number */
unsigned short st_mode; /* protection */
short st_nlink; /* number or hard links to the file */
short st_rfu1; /* reserved to apollo */
uid_t st_uid; /* user-id of owner */
short st_rfu2; /* reserved to apollo */
gid_t st_gid; /* group-id of owner */
long st_rfu3; /* reserved to apollo */
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 */
int st_spare3;
long st_blksize; /* optimal blocksize for file system i/o ops */
long st_blocks; /* actual number of blocks allocated */
long st_rfu4[5]; /* reserved to apollo */
long st_spare4[11]; /* reserved to apollo */
};
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 directory 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 inode. 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 0010000 /* socket */
#define S_IFIFO S_IFSOCK /* for sys5.3 compatibility */
#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)).
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 directory.
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire pathname 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.
NOTES
The fields in the stat structure currently marked st_spare1, st_spare2,
and st_spare3 are intended to allow future expansion of inode time stamps
to 64 bits. Their existence may cause problems for programs that depend
on the time stamps being contiguous (in calls to utimes(2)).
SEE ALSO
chmod(2), chown(2), utimes(2)
DIAGNOSTICS
A successful call returns 0. A failed call returns -1 and sets errno as
indicated under "Errors."
BUGS
Applying fstat to a socket (and thus to a pipe) returns a zeroed buffer,
except for the blocksize field, and a unique device and inode number.