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 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.

-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. 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/.