srm is a secure replacement for rm(1). Unlike the standard rm, it
overwrites the data in the target files before unlinking them. This
prevents command-line recovery of the data by examining the raw block
device. It may also help to frustrate a physical examination of the
disk, although it's unlikely that it can completely protect against
this type of recovery.

srm uses algorithms found in "Secure Deletion of Data from Magnetic
and Solid- State Memory" by Peter Gutmann and THC Secure Delete (the
overwrite, truncate, rename, unlink sequence).

Please note that srm will only work on file systems that overwrite
blocks in place. In particular, it will *NOT* work on reiserfs or
the vast majority of journaled file systems. It should work on ext2,
FAT-based file systems, and the BSD native file system. On ext3, srm
will try to disable the journaling of data (please see the verbose
output if this fails).