Provided by: perforate_1.2-5.1_amd64 
NAME
zum - free disk space by making holes in files
SYNOPSIS
zum [FILE]...
DESCRIPTION
zum reads a files list on the command line and attempts to perforate these files. Perforation means,
that series of `0' bytes are replaced by lseek(2)s, thus giving the file system a chance of not
allocating real disk space for those bytes.
EXAMPLE
find . -type f -print0 | xargs -0 zum
If you zum under /boot, where your kernel image lives, your system will become unbootable unless you run
lilo again.
AUTHOR
Oleg Kibirev <oleg@gd.cs.CSUFresno.edu>. Manual page by Heiko Schlittermann <heiko@lotte.sax.de>.