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¶
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.
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
ftp://ftp.kernel.org/pub/linux/utils/util-linux/.