fallocate

Reserve or deallocate disk space to files. The utility allocates space without zeroing.

Reserve a file taking up 700MB of disk space:

fallocate --length {{700M}} {{path/to/file}}

Shrink an already allocated file by 200MB:

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

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

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