NAME

stat, lstat, fstat, fstatat, — get file status

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/stat.h>

int
stat(const char *path, struct stat *sb);

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

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

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

int
fstatat(int fd, const char *path, struct stat *sb, 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 function 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. The fstat() function obtains the same information about an open file known by the file descriptor fd.

fstatat() works the same way as stat() (or lstat() if AT_SYMLINK_NOFOLLOW is set in flag) except if path is relative. In that case, it is looked up from a directory whose file descriptor was passed as fd. Search permission is required on this directory. fd can be set to AT_FDCWD in order to specify the current directory.

The sb argument is a pointer to a stat structure as defined by <sys/stat.h> and into which information is placed concerning the file.

The Standard Structure

The following standards-compliant fields are defined in the structure:

Type	Entry	Description
dev_t	st_dev	device ID containing the file
ino_t	st_ino	serial number of the file (inode number)
mode_t	st_mode	mode of the file
nlink_t	st_nlink	number of hard links to the file
uid_t	st_uid	user ID of the owner
gid_t	st_gid	group ID of the owner
dev_t	st_rdev	device type (character or block special)
off_t	st_size	size of the file 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
blksize_t	st_blksize	preferred I/O block size (fs-specific)
blkcnt_t	st_blocks	blocks allocated for the file

These are specified in the IEEE Std 1003.1-2004 (“POSIX.1”) standard. The st_ino and st_dev fields taken together uniquely identify the file within the system. Most of the types are defined in types(3).

The time-related fields are:

The size-related fields of the struct stat are as follows:

The status information word st_mode contains bits that define the access mode (see chmod(2)) and the type (see dirent(3)) of the file. The following macros can be used to test whether a file is of the specified type. The value m supplied to the macros is the value of st_mode.

The macros evaluate to a non-zero value if the test is true or to the value 0 if the test is false.

NetBSD Extensions

The following additional NetBSD specific fields are present:

Type	Entry	Description
long	st_atimensec	last access (nanoseconds)
long	st_mtimensec	last modification (nanoseconds)
long	st_ctimensec	last status change (nanoseconds)
time_t	st_birthtime	time of inode creation
long	st_birthtimensec	inode creation (nanoseconds)
uint32_t	st_flags	user defined flags for the file
uint32_t	st_gen	file generation number
uint32_t	st_spare[2]	implementation detail

However, if _NETBSD_SOURCE is furthermore defined, instead of the above, the following are present in the structure:

Type	Entry	Description
struct timespec	st_atimespec	time of last access
struct timespec	st_mtimespec	time of last modification
struct timespec	st_birthtimespec	time of creation
uint32_t	st_flags	user defined flags
uint32_t	st_gen	file generation number
uint32_t	st_spare[2]	implementation detail

In this case the following macros are provided for convenience:

#if defined(_NETBSD_SOURCE) 
  #define st_atime                st_atimespec.tv_sec 
  #define st_atimensec            st_atimespec.tv_nsec 
  #define st_mtime                st_mtimespec.tv_sec 
  #define st_mtimensec            st_mtimespec.tv_nsec 
  #define st_ctime                st_ctimespec.tv_sec 
  #define st_ctimensec            st_ctimespec.tv_nsec 
  #define st_birthtime            st_birthtimespec.tv_sec 
  #define st_birthtimensec        st_birthtimespec.tv_nsec 
#endif

The status information word st_flags has the following bits:

Constant	Description
UF_NODUMP	do not dump a file
UF_IMMUTABLE	file may not be changed
UF_APPEND	writes to file may only append
UF_OPAQUE	directory is opaque wrt. union
SF_ARCHIVED	file is archived
SF_IMMUTABLE	file may not be changed
SF_APPEND	writes to file may only append

For a description of the flags, see chflags(2).

RETURN VALUES

The stat(), lstat(), fstat(), and fstatat() functions return the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

COMPATIBILITY

Previous versions of the system used different types for the st_dev, st_uid, st_gid, st_rdev, st_size, st_blksize and st_blocks fields.

ERRORS

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

In addition, fstatat() will fail if:

fstat() will fail if:

STANDARDS

stat(), lstat(), and fstat() conform to IEEE Std 1003.1-2004 (“POSIX.1”). fstatat() conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

HISTORY

A stat() function call appeared in Version 2 AT&T UNIX. A lstat() function call appeared in 4.2BSD.

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 file serial number.

Manual browser: fstatat(2)