NAME

stat – get file status

SYNOPSIS

#include <sys/stat.h>

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

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

DESCRIPTION

The stat() function obtains information about the named file and write it to the area pointed to by the buf argument. The path argument points to a pathname naming a file. All directories listed in the path name leading to the file must be searchable.

The fstat() function obtains information about an open file associated with the file descriptor fildes, and writes it to the area pointed to by buf.

The buf argument is a pointer to a stat structure into which information is placed concerning the file.

The contents of the structure pointed to by buf include the following members:

mode_t  st_mode;        /* File mode */
ino_t   st_ino;         /* Inode number */
dev_t   st_dev;         /* ID of device containing */
                        /* a directory entry for this file */
dev_t   st_rdev;        /* ID of device */
                        /* This entry is defined only for */
                        /* char special or block special files */
nlink_t st_nlink;       /* Number of links */
uid_t   st_uid;         /* User ID of the file's owner */
gid_t   st_gid;         /* Group ID of the file's group */
off_t   st_size;        /* File size 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 */
                        /* Times measured in seconds since */
                        /* 00:00:00 UTC, Jan. 1, 1970 */
long    st_blksize;     /* Preferred I/O block size */
long    st_blocks;      /* Number st_blksize blocks allocated */

st_mode

The mode of the file specifies both the permissions to use and the type of node to be created. It should be a combination (using bitwise OR) of one of the file types and the permissions for the node.

The file type and the permissions are specified in stat.h. The permissions of the created node are (mode & ~umask). Symbolic links are not supported so the mode of a file may not be S_IFLNK.

st_ino

This field uniquely identifies the file in a given file system. The pair st_ino and st_dev uniquely identifies regular files.

st_dev

This field uniquely identifies the file system that contains the file. Its value may be used as input to the ustat() function to determine more information about this file system. No other meaning is associated with this value.

st_rdev

This field should be used only by administrative commands. It is valid only for block special or character special files and only has meaning on the system where the file was configured.

st_nlink

This field should be used only by administrative commands.

st_uid

The user ID of the file’s owner.

st_gid

The group ID of the file’s group.

st_size

For regular files, this is the address of the end of the file. For block special or character special, this is not defined.

st_atime

Time when file data was last accessed. Changed by the following function: read .

st_mtime

Time when data was last modified. Changed by the following function: write .

st_ctime

Time when file status was last changed. Changed by the following functions: chmod(), link(), unlink(), and write().

st_blksize

A hint as to the “best” unit size for I/O operations. This field is not defined for block-special or character-special files.

st_blocks

The total number of physical blocks of size 512 bytes actually allocated on disk. This field is not defined for block-special or character-special files.

RETURN VALUES

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

ERRORS

These functions are members of Unison’s IOLIB family of functions. IOLIB is implemented as a message passing and generalized interface layer. Each Unison I/O server is responsible for its own error reporting.

For an exact list of error codes returned by a particular server, refer to that server’s documentation in the Unison Programmer’s Guide for each specific platform.

Servers may implement these errors codes in response to these functions.

stat() fails if one or more of the following are true:

EACCES

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

EFAULT

buf or path points to an illegal address.

EMULTIHOP

Components of path require hopping to multiple remote machines and the file system does not allow it.

ENAMETOOLONG

The length of the path argument exceeds {PATH_MAX}, or the length of a path component exceeds {NAME_MAX} while {_POSIX_NO_TRUNC} is in effect.

ENOENT

The named file does not exist or is the null pathname.

ENOLINK

path points to a remote machine and the link to that machine is no longer active.

ENOTDIR

A component of the path prefix is not a directory.

SEE ALSO

chmod(), link(), read(), unlink(), write(),