statfs, fstatfs - get filesystem statistics


   #include <sys/vfs.h>    /* or <sys/statfs.h> */

   int statfs(const char *path, struct statfs *buf);
   int fstatfs(int fd, struct statfs *buf);


   The   statfs()   system   call  returns  information  about  a  mounted
   filesystem.  path is the  pathname  of  any  file  within  the  mounted
   filesystem.    buf   is   a  pointer  to  a  statfs  structure  defined
   approximately as follows:

       struct statfs {
           __fsword_t f_type;    /* Type of filesystem (see below) */
           __fsword_t f_bsize;   /* Optimal transfer block size */
           fsblkcnt_t f_blocks;  /* Total data blocks in filesystem */
           fsblkcnt_t f_bfree;   /* Free blocks in filesystem */
           fsblkcnt_t f_bavail;  /* Free blocks available to
                                    unprivileged user */
           fsfilcnt_t f_files;   /* Total file nodes in filesystem */
           fsfilcnt_t f_ffree;   /* Free file nodes in filesystem */
           fsid_t     f_fsid;    /* Filesystem ID */
           __fsword_t f_namelen; /* Maximum length of filenames */
           __fsword_t f_frsize;  /* Fragment size (since Linux 2.6) */
           __fsword_t f_flags;   /* Mount flags of filesystem
                                    (since Linux 2.6.36) */
           __fsword_t f_spare[xxx];
                           /* Padding bytes reserved for future use */

       Filesystem types:

          ADFS_SUPER_MAGIC      0xadf5
          AFFS_SUPER_MAGIC      0xadff
          BDEVFS_MAGIC          0x62646576
          BEFS_SUPER_MAGIC      0x42465331
          BFS_MAGIC             0x1badface
          BINFMTFS_MAGIC        0x42494e4d
          BTRFS_SUPER_MAGIC     0x9123683e
          CGROUP_SUPER_MAGIC    0x27e0eb
          CIFS_MAGIC_NUMBER     0xff534d42
          CODA_SUPER_MAGIC      0x73757245
          COH_SUPER_MAGIC       0x012ff7b7
          CRAMFS_MAGIC          0x28cd3d45
          DEBUGFS_MAGIC         0x64626720
          DEVFS_SUPER_MAGIC     0x1373
          DEVPTS_SUPER_MAGIC    0x1cd1
          EFIVARFS_MAGIC        0xde5e81e4
          EFS_SUPER_MAGIC       0x00414a53
          EXT_SUPER_MAGIC       0x137d
          EXT2_OLD_SUPER_MAGIC  0xef51
          EXT2_SUPER_MAGIC      0xef53
          EXT3_SUPER_MAGIC      0xef53
          EXT4_SUPER_MAGIC      0xef53
          FUSE_SUPER_MAGIC      0x65735546
          FUTEXFS_SUPER_MAGIC   0xbad1dea
          HFS_SUPER_MAGIC       0x4244
          HOSTFS_SUPER_MAGIC    0x00c0ffee
          HPFS_SUPER_MAGIC      0xf995e849
          HUGETLBFS_MAGIC       0x958458f6
          ISOFS_SUPER_MAGIC     0x9660
          JFFS2_SUPER_MAGIC     0x72b6
          JFS_SUPER_MAGIC       0x3153464a
          MINIX_SUPER_MAGIC     0x137f /* orig. minix */
          MINIX_SUPER_MAGIC2    0x138f /* 30 char minix */
          MINIX2_SUPER_MAGIC    0x2468 /* minix V2 */
          MINIX2_SUPER_MAGIC2   0x2478 /* minix V2, 30 char names */
          MINIX3_SUPER_MAGIC    0x4d5a /* minix V3 fs, 60 char names */
          MQUEUE_MAGIC          0x19800202
          MSDOS_SUPER_MAGIC     0x4d44
          NCP_SUPER_MAGIC       0x564c
          NFS_SUPER_MAGIC       0x6969
          NILFS_SUPER_MAGIC     0x3434
          NTFS_SB_MAGIC         0x5346544e
          OCFS2_SUPER_MAGIC     0x7461636f
          OPENPROM_SUPER_MAGIC  0x9fa1
          PIPEFS_MAGIC          0x50495045
          PROC_SUPER_MAGIC      0x9fa0
          PSTOREFS_MAGIC        0x6165676c
          QNX4_SUPER_MAGIC      0x002f
          QNX6_SUPER_MAGIC      0x68191122
          RAMFS_MAGIC           0x858458f6
          REISERFS_SUPER_MAGIC  0x52654973
          ROMFS_MAGIC           0x7275
          SELINUX_MAGIC         0xf97cff8c
          SMACK_MAGIC           0x43415d53
          SMB_SUPER_MAGIC       0x517b
          SOCKFS_MAGIC          0x534f434b
          SQUASHFS_MAGIC        0x73717368
          SYSFS_MAGIC           0x62656572
          SYSV2_SUPER_MAGIC     0x012ff7b6
          SYSV4_SUPER_MAGIC     0x012ff7b5
          TMPFS_MAGIC           0x01021994
          UDF_SUPER_MAGIC       0x15013346
          UFS_MAGIC             0x00011954
          USBDEVICE_SUPER_MAGIC 0x9fa2
          V9FS_MAGIC            0x01021997
          VXFS_SUPER_MAGIC      0xa501fcf5
          XENFS_SUPER_MAGIC     0xabba1974
          XENIX_SUPER_MAGIC     0x012ff7b4
          XFS_SUPER_MAGIC       0x58465342
          _XIAFS_SUPER_MAGIC    0x012fd16d

   Most    of     these     MAGIC     constants     are     defined     in
   /usr/include/linux/magic.h, and some are hardcoded in kernel sources.

   The  f_flags is a bit mask indicating mount options for the filesystem.
   It contains zero or more of the following bits:

          Mandatory locking is permitted on the filesystem (see fcntl(2)).

          Do not update access times; see mount(2).

          Disallow access to device special files on this filesystem.

          Do not update directory access times; see mount(2).

          Execution of programs is disallowed on this filesystem.

          The set-user-ID and set-group-ID bits are ignored by exec(3) for
          executable files on this filesystem

          This filesystem is mounted read-only.

          Update atime relative to mtime/ctime; see mount(2).

          Writes  are  synched  to  the  filesystem  immediately  (see the
          description of O_SYNC in open(2)).

   Nobody knows what f_fsid is supposed to contain (but see below).

   Fields that are undefined for a particular filesystem are set to 0.

   fstatfs() returns the same information about an open file referenced by
   descriptor fd.


   On  success,  zero is returned.  On error, -1 is returned, and errno is
   set appropriately.


   EACCES (statfs()) Search permission is denied for a  component  of  the
          path prefix of path.  (See also path_resolution(7).)

   EBADF  (fstatfs()) fd is not a valid open file descriptor.

   EFAULT buf or path points to an invalid address.

   EINTR  This call was interrupted by a signal; see signal(7).

   EIO    An I/O error occurred while reading from the filesystem.

   ELOOP  (statfs())   Too   many   symbolic  links  were  encountered  in
          translating path.

          (statfs()) path is too long.

   ENOENT (statfs()) The file referred to by path does not exist.

   ENOMEM Insufficient kernel memory was available.

   ENOSYS The filesystem does not support this call.

          (statfs()) A component of the path  prefix  of  path  is  not  a

          Some  values  were  too  large to be represented in the returned


   Linux-specific.  The Linux statfs() was inspired by the 4.4BSD one (but
   they do not use the same structure).


   The  __fsword_t  type  used  for various fields in the statfs structure
   definition is a glibc internal type, not intended for public use.  This
   leaves  the  programmer  in a bit of a conundrum when trying to copy or
   compare  these  fields  to  local  variables  in  a   program.    Using
   unsigned int for such variables suffices on most systems.

   The  original  Linux  statfs()  and  fstatfs()  system  calls  were not
   designed with extremely large file sizes in mind.  Subsequently,  Linux
   2.6 added new statfs64() and fstatfs64() system calls that employ a new
   structure, statfs64.  The new structure contains the same fields as the
   original  statfs  structure,  but  the  sizes  of  various  fields  are
   increased, to accommodate large file sizes.   The  glibc  statfs()  and
   fstatfs()   wrapper   functions  transparently  deal  with  the  kernel

   Some  systems  have  only  <sys/vfs.h>,   other   systems   also   have
   <sys/statfs.h>,  where  the  former  includes  the latter.  So it seems
   including the former is the best choice.

   LSB has deprecated the library calls statfs() and fstatfs()  and  tells
   us to use statvfs(2) and fstatvfs(2) instead.

   The f_fsid field
   Solaris,  Irix  and  POSIX have a system call statvfs(2) that returns a
   struct statvfs (defined in <sys/statvfs.h>) containing an unsigned long
   f_fsid.   Linux,  SunOS, HP-UX, 4.4BSD have a system call statfs() that
   returns a struct statfs (defined in <sys/vfs.h>)  containing  a  fsid_t
   f_fsid,  where  fsid_t  is defined as struct { int val[2]; }.  The same
   holds for FreeBSD, except that it uses the include file <sys/mount.h>.

   The general idea is that f_fsid contains some random  stuff  such  that
   the  pair  (f_fsid,ino)  uniquely  determines  a  file.  Some operating
   systems use (a variation on) the device number, or  the  device  number
   combined  with the filesystem type.  Several operating systems restrict
   giving out the f_fsid field to the superuser  only  (and  zero  it  for
   unprivileged  users),  because  this field is used in the filehandle of
   the filesystem when NFS-exported, and  giving  it  out  is  a  security

   Under  some  operating  systems,  the  fsid  can  be used as the second
   argument to the sysfs(2) system call.


   From Linux 2.6.38 up to and including Linux 3.1, fstatfs() failed  with
   the error ENOSYS for file descriptors created by pipe(2).


   stat(2), statvfs(3), path_resolution(7)


   This  page  is  part of release 4.09 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


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