fallocate
preallocate space to a file
see also :
truncate
Synopsis
fallocate
[-n] [-o offset]
-l length filename
add an example, a script, a trick and tips
examples
source
fallocate -l 512m /mnt/swap
chmod 600 /mnt/swap
mkswap /mnt/swap
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
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.
availability
The fallocate command is part of the util-linux package and is
available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
see also
fallocate,
posix_fallocate, truncate
authors
Eric Sandeen
<sandeen[:at:]redhat[:dot:]com>
Karel Zak <kzak[:at:]redhat[:dot:]com>