zerofree(8) on Linux
The text 4c9221acf0fe, as Debian 8 (Jessie) shipped it.
zero free blocks from ext2, ext3 and ext4 file-systems
Flags it lists
-
-f -
-n -
-v
The text 4c9221acf0fe, as Debian 8 (Jessie) shipped it.
zero free blocks from ext2, ext3 and ext4 file-systems
-f
-n
-v