Defines the data structures returned by the stat family of subroutines.
The stat data structure in the /usr/include/sys/stat.h file returns information for the stat, fstat, lstat, statx, and fstatx subroutines.
The stat data structure contains the following fields:
| Item | Description |
|---|---|
| st_dev | Device that contains a directory entry for this file. |
| st_ino | Index of this file on its device. A file is uniquely identified by specifying the device on which it resides and its index on that device. |
| st_mode | File mode. The possible file mode values are given in the description of the /usr/include/sys/mode.h file. |
| st_nlink | Number of hard links (alternate directory entries) to the file created using the link subroutine. |
| st_access | Field is not implemented. All bits are returned as zero. |
| st_size | Number of bytes in a file (including any holes). This field also defines the position of the end-of-file mark for the file. The end-of-file mark is updated only by subroutines, for example the write subroutine. If the file is mapped by the shmat subroutine and a value is stored into a page past the end-of-file mark, that mark will be updated to include this page when the file is closed or forced to permanent storage. |
| st_rdev | ID of the device. This field is defined only for block or character special files. |
| st_atime | Time when file data was last accessed. st_atime and st_atime_n taken together represent the last file access time in number of seconds and nanoseconds since the epoch. |
| st_atime_n | Time when file data was last accessed. st_atime and st_atime_n taken together represent the last file access time in number of seconds and nanoseconds since the epoch. |
| st_mtime | Time when file data was last modified. st_mtime and st_mtime_n taken together represent the last file modification time in number of seconds and nanoseconds since the epoch. |
| st_mtime_n | Time when file data was last modified. st_mtime and st_mtime_n taken together represent the last file modification time in number of seconds and nanoseconds since the epoch. |
| st_ctime | Time when the file status was last changed. st_ctime and st_ctime_n taken together represent the last file status change in number of seconds and nanoseconds since the epoch. |
| st_ctime_n | Time when the file status was last changed. st_ctime and st_ctime_n taken together represent the last file status change in number of seconds and nanoseconds since the epoch. |
| st_blksize | Size, in bytes of each block of the file. |
| st_blocks | Number of blocks actually used by the file (measured in the units specified by the DEV_BSIZE constant). |
| st_gen | Generation number of this i-node. |
| st_type | Type of the v-node
for the object. This is one of the following
values, which are defined in the /usr/include/sys/vnode.h file:
|
| st_vfs | Virtual file system (VFS) ID, which identifies the VFS that contains the file. By comparing this value with the VFS numbers returned by the mntctl subroutine, the name of the host where the file resides can be identified. |
| st_vfstype | File-system type, as defined in the /usr/include/sys/vmount.h file. |
| st_flag |
Flag indicating whether the file or the directory is a virtual
mount point. This flag can have the following values:
|
| st_uid | File owner ID. |
| st_gid | File group ID. |
The stat64 data structure in the /usr/include/sys/stat.h file returns information for the stat64, fstat64, and lstat64 subroutines. The stat64 structure contains the same fields as the stat structure, with the exception of the following field:
| Item | Description |
|---|---|
| st_size | Number of bytes in a file. The st_size field is a 64-bit quantity, allowing file sizes greater than OFF_MAX. The st_size field of the stat64 structure is of the type off64_t. |
For remote files, the st_atime, st_mtime, and st_ctime fields contain the time at the server.
The value of the st_atime field can be changed by the following subroutines:
The values of the st_ctime and st_mtime fields can be set by the following subroutines:
In addition, the shmdt subroutine can change the st_mtime field, and the chmod, fchmod, chown, chownx, fchown, and fchownx subroutines can change the st_ctime field.
Because they can create a new object, the open, openx, creat, symlink, mknod, mkdir, and pipe subroutines can set the st_atime, st_ctime, and st_mtime fields.