Zeroer software effectively clears empty space on any disk.
The principle behind zeroer is simple: the utility writes huge zero-padded memory blocks to a file. This approach is similar to the one used by dd program, but zeroer dynamically reduces the blockwriter's buffer size when the disk is close to being full. This ensures that smaller fragments of unallocated partition space are also flushed, while the largest unallocated disk areas can be written with huge blocks for more speed.
It's worth noting that zeroer's principle may not work reliably on every file system, since the utility doesn't have precise knowledge of how a file system works. However, most file systems use a mix of centralized disk block addressing tables (e.g. inodes, file allocation table) and multiple peripheral directory/file descriptors. Zeroer has been multi-pass tested on UFS, FAT, and NTFS, and the results showed that zeroer operates quite reliably on these file systems.
To use zeroer, simply enter "zeroer filename" and choose the desired buffer size with the -b or --buffersize option. Overall, if you need a reliable utility to flush unallocated partition space without wiping existing files, zeroer seems to be a good choice.
Version 0.1: N/A