Scroll to navigation

USTAT(2) Linux Programmer's Manual USTAT(2)


ustat - get filesystem statistics


#include <sys/types.h>
#include <unistd.h>    /* libc[45] */
#include <ustat.h>     /* glibc2 */
int ustat(dev_t dev, struct ustat *ubuf);


ustat() returns information about a mounted filesystem. dev is a device number identifying a device containing a mounted filesystem. ubuf is a pointer to a ustat structure that contains the following members:

daddr_t f_tfree;      /* Total free blocks */
ino_t   f_tinode;     /* Number of free inodes */
char    f_fname[6];   /* Filsys name */
char    f_fpack[6];   /* Filsys pack name */

The last two fields, f_fname and f_fpack, are not implemented and will always be filled with null bytes ('\0').


On success, zero is returned and the ustat structure pointed to by ubuf will be filled in. On error, -1 is returned, and errno is set appropriately.


ubuf points outside of your accessible address space.
dev does not refer to a device containing a mounted filesystem.
The mounted filesystem referenced by dev does not support this operation, or any version of Linux before 1.3.16.


Since version 2.28, glibc no longer provides a wrapper for this system call.




ustat() is deprecated and has been provided only for compatibility. All new programs should use statfs(2) instead.

HP-UX notes

The HP-UX version of the ustat structure has an additional field, f_blksize, that is unknown elsewhere. HP-UX warns: For some filesystems, the number of free inodes does not change. Such filesystems will return -1 in the field f_tinode. For some filesystems, inodes are dynamically allocated. Such filesystems will return the current number of free inodes.


stat(2), statfs(2)


This page is part of release 5.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

2019-03-06 Linux