Provided by: util-linux_2.20.1-5.1ubuntu20_amd64 bug


       fallocate - preallocate space to a file


       fallocate [-n] [-o offset] -l length filename


       fallocate  is  used  to  preallocate  blocks to a file.  For filesystems which support the
       fallocate system call, this is done quickly by  allocating  blocks  and  marking  them  as
       uninitialized,  requiring  no  IO to the data blocks.  This is much faster than creating a
       file by filling it with zeros.

       As of the Linux Kernel v2.6.31, the fallocate system call is supported by the btrfs, ext4,
       ocfs2, and xfs filesystems.

       The exit code returned by fallocate is 0 on success and 1 on failure.


       The  length  and  offset arguments may be followed by binary (2^N) suffixes KiB, MiB, GiB,
       TiB, PiB and EiB (the "iB" is optional, e.g. "K" has the same meaning as "KiB") or decimal
       (10^N) suffixes KB, MB, GB, PB and EB.

       -h, --help
              Print help and exit.

       -n, --keep-size
              Do not modify the apparent length of the file. This may effectively allocate blocks
              past EOF, which can be removed with a truncate.

       -o, --offset offset
              Specifies the beginning offset of the allocation, in bytes.

       -l, --length length
              Specifies the length of the allocation, in bytes.


       Eric Sandeen <>
       Karel Zak <>


       fallocate(2), posix_fallocate(3), truncate(1)


       The  fallocate  command  is  part  of  the  util-linux  package  and  is  available   from