stat(2) System Calls Manual stat(2)
Name
stat, lstat, fstat - get file status
Syntax
#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
The system call obtains information about the file path. Read, write, or execute permission of the named file is not required, but all
directories specified in the path name that leads to the file must be reachable.
The system call is like except when a named file is a symbolic link. In this instance, returns information about the link; returns infor-
mation about the file that is referenced by the link.
The system call and the system call obtain the same information about an open file referenced by the argument descriptor.
The buf is a pointer to a structure. Information about a file is placed in the structure. The contents of the structure pointed to by buf
includes the following:
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 */
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;
u_long st_gennum; /* file generation number */
};
st_atime The time when file data was last accessed. This is changed by the system calls and For efficiency, st_atime is not set when a
directory is searched.
st_mtime The time when data was last modified. It is not set by changes of owner, group, link count, or mode. It is changed by the
system calls and
st_ctime The time when file status was last changed. It is set by writing and changing the i-node. It can be changed by the following
system calls: and
The status information word st_mode has the following 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_IFIFO 0010000 /* FIFO - named pipe */
#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. For further information, see
When fd is associated with a pipe, returns a buffer with only st_blksize set.
Environment
SYSTEM_FIVE
Unlike the System V definition, ELOOP is a possible error condition.
Restrictions
Applying to a socket returns a zeroed buffer and [EOPNOTSUPP].
The fields in the stat structure marked st_spare1, st_spare2, and st_spare3 are used when inode time stamps expand to 64 bits. This, how-
ever, can break certain programs that depend on the time stamps being contiguous in calls to
Return Values
Upon successful completion, a value of zero (0) is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
Diagnostics
The and system calls fail if any of the following is true:
[EACCES] Search permission is denied for a component of the path prefix.
[EFAULT] The buf or name points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to the file system.
[ELOOP] Too many symbolic links were encountered in translating the pathname.
[ENAMETOOLONG] A component of a pathname exceeds 255 characters, or an entire path name exceeds 1023 characters.
[ENOENT] The named file does not exist or path points to an empty string and the environment defined is POSIX or SYSTEM_FIVE.
[ENOTDIR] A component of the path prefix is not a directory.
The system call fails if one or more of the following are true:
[EBADF] The fildes is not a valid open file descriptor.
[EFAULT] The buf points to an invalid address.
[EIO] An I/O error occurred while reading from or writing to the file system.
[EOPNOTSUPP] The file descriptor points to a socket.
[ETIMEDOUT] A connect request or remote file operation failed because the connected party did not respond after a period of time deter-
mined by the communications protocol.
See Also
chmod(2), chown(2), link(2), mknod(2), read(2), unlink(2), utimes(2), write(2)
stat(2)