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 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 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 ⟨[email protected]⟩
Karel Zak ⟨[email protected]⟩
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)
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