fallocate

Reserve or deallocate disk space to files. The utility allocates space without zeroing. More information: https://manned.org/fallocate.

• Reserve a file taking up 700 MiB of disk space:

fallocate --length 700M path/to/file

• Shrink an already allocated file by 200 MiB:

fallocate --collapse-range --length 200M path/to/file

• Shrink 20 MB of space after 100 MiB in a file:

fallocate --collapse-range --offset 100M --length 20M path/to/file