FALLOCATE(1) User Commands FALLOCATE(1)NAMEfallocate - preallocate or deallocate space to a file
SYNOPSISfallocate [-n] [-p] [-o offset] -l length filename
DESCRIPTIONfallocate is used to manipulate the allocated disk space for a file,
either to deallocate or preallocate it. For filesystems which support
the fallocate system call, preallocation 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 effec‐
tively 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
Display help text and exit.
-V, --version
Display version information and exit.
AUTHORS
Eric Sandeen ⟨sandeen@redhat.com⟩
Karel Zak ⟨kzak@redhat.com⟩
SEE ALSOfallocate(2), posix_fallocate(3), truncate(1)AVAILABILITY
The fallocate command is part of the util-linux package and is avail‐
able from Linux Kernel Archive ⟨ftp://ftp.kernel.org/pub/linux/utils
/util-linux/⟩.
util-linux September 2011 FALLOCATE(1)