centos man page for fallocate

FALLOCATE(1)							   User Commands						      FALLOCATE(1)

NAME
       fallocate - preallocate space to a file

SYNOPSIS
       fallocate [-n] [-p] [-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 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.

OPTIONS
       The  length  and offset arguments may be followed by the multiplicative suffixes KiB=1024, MiB=1024*1024, and so on for GiB, TiB, PiB, EiB,
       ZiB and YiB (the "iB" is optional, e.g. "K" has the same meaning as "KiB") or the suffixes KB=1000, MB=1000*1000, and so on for GB, TB, PB,
       EB, ZB and YB.

       -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.

       -p, --punch-hole
	      Punch holes in the file, the range should not exceed the length of the file.

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

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

       -h, --help
	      Print help and exit.

       -V, --version
	      Print version and exit.

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 package and is available from Linux Kernel Archive <ftp://ftp.kernel.org/pub/linux/utils
       /util-linux/>.

util-linux							  September 2011						      FALLOCATE(1)