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NAME

       fallocate - preallocate space to a file.

SYNOPSIS

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

DESCRIPTION

       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.

OPTIONS

       -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.
              Suffixes  of  k,  m,  g, t, p, e may be specified to denote KiB,
              MiB, GiB, etc.

       -l, --length length
              Specifies the length of the allocation, in bytes.   Suffixes  of
              k,  m, g, t, p, e may be specified to denote KiB, MiB, GiB, etc.

AUTHORS

       Eric Sandeen <sandeen@redhat.com>
       Karel Zak <kzak@redhat.com>

SEE ALSO

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

AVAILABILITY

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