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  allo-
       cating 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)  suf-
       fixes  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 effec-
              tively allocate blocks past EOF, which can  be  removed  with  a

       -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 <sandeen@redhat.com>
       Karel Zak <kzak@redhat.com>

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

       The  fallocate  command is part of the util-linux package and is avail-
       able from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

util-linux                         July 2009                      FALLOCATE(1)
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