STAT(2) BSD STAT(2)
NAME
stat, lstat, fstat - get file status
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
int stat(path, buf)
const char *path;
struct stat *buf;
lstat(path, buf)
const char *path;
struct stat *buf;
int fstat(fildes, buf)
int fildes;
struct stat *buf;
DESCRIPTION
stat returns 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.
If the final component of path names a symbolic link, the link will be
traversed and the pathname resolution will continue.
lstat returns information about the file named by the path argument. If
the named file is a symbolic link, lstat returns information about the
symbolic link itself. In that case, the returned st_size field of the
stat structure contains the length of the link, the st_mode field
specifies that it is a link (s_iflink), and the remaining fields are set
to "default" values. Otherwise, the behavior of lstat is the same as
described for stat.
fstat obtains the same information about an open file referenced by the
file descriptor, fildes.
These functions update the time-related fields associated with the file
(or file descriptor) before writing into the stat structure.
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 */
long st_hostid[2] /* if non-zero: machine host identifier; uniquely */
/* identifies the node at which object resides */
long st_spare4[8]
};
For maximum portability, POSIX 1003.1 applications should restrict
themselves to using only the st_atime, st_ctime, st_dev, st_gid, st_ino,
st_mode, st_mtime, st_nlink, st_size and st_uid fields.
For maximum portability, XPG3 applications should restrict themselves to
using only the above fields and the st_rdev field.
The time members are defined as follows:
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).
Status information on file modes and file type are defined in sys/stat.h.
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 or path points to an empty
string.
[EACCES] Search permission is denied for a component of the path
prefix.
[ELOOP] Too many symbolic links were encountered in translating
the pathname.
[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.