Secure Deletion of Data from Magnetic and Solid-State Memory
Secure Deletion of Data from Magnetic and Solid-State Memory `shred': Remove files more securely `shred' overwrites devices or files, to help prevent even very expensive hardware from recovering the data. Ordinarily when you remove a file (*note rm invocation::), the data is not actually destroyed. Only the index listing where the file is stored is destroyed, and the storage is made available for reuse. There are undelete utilities that will attempt to reconstruct the index and can bring the file back if the parts were not reused. On a busy system with a nearly-full drive, space can get reused in a few seconds. But there is no way to know for sure. If you have sensitive data, you may want to be sure that recovery is not possible by actually overwriting the file with non-sensitive data. The best way to remove something irretrievably is to destroy the media it's on with acid, melt it down, or the like. For cheap removable media like floppy disks, this is the preferred