statvfs(3)

NAME

   statvfs, fstatvfs - get filesystem statistics

SYNOPSIS

   #include <sys/statvfs.h>

   int statvfs(const char *path, struct statvfs *buf);
   int fstatvfs(int fd, struct statvfs *buf);

DESCRIPTION

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

       struct statvfs {
           unsigned long  f_bsize;    /* Filesystem block size */
           unsigned long  f_frsize;   /* Fragment size */
           fsblkcnt_t     f_blocks;   /* Size of fs in f_frsize units */
           fsblkcnt_t     f_bfree;    /* Number of free blocks */
           fsblkcnt_t     f_bavail;   /* Number of free blocks for
                                         unprivileged users */
           fsfilcnt_t     f_files;    /* Number of inodes */
           fsfilcnt_t     f_ffree;    /* Number of free inodes */
           fsfilcnt_t     f_favail;   /* Number of free inodes for
                                         unprivileged users */
           unsigned long  f_fsid;     /* Filesystem ID */
           unsigned long  f_flag;     /* Mount flags */
           unsigned long  f_namemax;  /* Maximum filename length */
       };

   Here  the types fsblkcnt_t and fsfilcnt_t are defined in <sys/types.h>.
   Both used to be unsigned long.

   The field f_flag is a bit mask indicating  various  options  that  were
   employed  when  mounting  this filesystem.  It contains zero or more of
   the following flags:

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

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

   ST_NODEV
          Disallow access to device special files on this filesystem.

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

   ST_NOEXEC
          Execution of programs is disallowed on this filesystem.

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

   ST_RDONLY
          This filesystem is mounted read-only.

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

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

   It is unspecified whether all  members  of  the  returned  struct  have
   meaningful values on all filesystems.

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

RETURN VALUE

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

ERRORS

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

   EBADF  (fstatvfs()) 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  (statvfs())  Too  many  symbolic  links  were   encountered   in
          translating path.

   ENAMETOOLONG
          (statvfs()) path is too long.

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

   ENOMEM Insufficient kernel memory was available.

   ENOSYS The filesystem does not support this call.

   ENOTDIR
          (statvfs())  A  component  of  the  path prefix of path is not a
          directory.

   EOVERFLOW
          Some values were too large to be  represented  in  the  returned
          struct.

ATTRIBUTES

   For   an   explanation   of   the  terms  used  in  this  section,  see
   attributes(7).

   ┌──────────────────────┬───────────────┬─────────┐
   │Interface             │ Attribute     │ Value   │
   ├──────────────────────┼───────────────┼─────────┤
   │statvfs(), fstatvfs() │ Thread safety │ MT-Safe │
   └──────────────────────┴───────────────┴─────────┘

CONFORMING TO

   POSIX.1-2001, POSIX.1-2008.

   Only the  ST_NOSUID  and  ST_RDONLY  flags  of  the  f_flag  field  are
   specified  in  POSIX.1.   To obtain definitions of the remaining flags,
   one must define _GNU_SOURCE.

NOTES

   The Linux kernel has system calls statfs(2) and fstatfs(2)  to  support
   this library call.

   In  glibc  versions  before  2.13,  statvfs() populated the bits of the
   f_flag field by scanning  the  mount  options  shown  in  /proc/mounts.
   However,  starting  with  Linux 2.6.36, the underlying statfs(2) system
   call provides the necessary information  via  the  f_flags  field,  and
   since  glibc  version 2.13, the statvfs() function will use information
   from that field rather than scanning /proc/mounts.

   The glibc implementations of

      pathconf(path, _PC_REC_XFER_ALIGN);
      pathconf(path, _PC_ALLOC_SIZE_MIN);
      pathconf(path, _PC_REC_MIN_XFER_SIZE);

   respectively use the f_frsize, f_frsize, and f_bsize fields returned by
   a call to statvfs() with the argument path.

SEE ALSO

   statfs(2)

COLOPHON

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