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DirDiff is a powerful tool to scan, compare, synchronize and replicate files. It was originally designed for internal use at Cloanto for backup management and to simplify the maintenance of software master disks. Over the years, new features were implemented, the file comparison engine was enhanced and a graphical interface was added.
DirDiff can be used to compare (and optionally update) two disks. Several options can be set to finely tune this process.
DirDiff can be used to copy some files from hard disk to floppy, then use the floppy on another computer (for example at home), and from time to time automatically move the files which have changed to whichever medium contains the older version.
DirDiff can be used to compare bootable disks against new versions of the Amiga Workbench disks. It can selectively compare only the files used in both disks, skipping icon files if desired. So only messages regarding relevant files are generated. If desired, DirDiff can upgrade the system files on work disks in the same process.
When copying tens, or hundreds of Mbytes from one device to another, errors are more likely to occur and pass undetected than with normal, interactive use. Using DirDiff, at Cloanto we discovered faulty I/O configurations which caused only one or two bytes out of 100 million to be corrupt. We now always use DirDiff after each step in the preparation of master disks, both for floppy disks and for CD-ROMs, to make absolutely sure that no errors have occurred. When it finds certain errors, DirDiff does an additional check to make sure that the storage medium gives consistent results. It even double-checks the RAM locations it uses.
DirDiff is an invaluable tool to back-up a hard disk to a slower device, such as a magneto-optical disk, because it can copy only the files which have changed. Results can be achieved faster and in a less resource-consuming way. To make the process bullet-proof, the source directory can be locked, and differing files can be force-copied from hard disk to the optical disk even if they have an older date. Files from older backups which become unused can be deleted in the process. The combined use of these functions can deliver identical copies at a fraction of the time a standard "Copy" procedure would normally require.
DirDiff can detect even subtle differences between two items, such as a directory renamed from "WBStartup" to "WBStartup". Before DirDiff reports that two directories are identical, it checks not only the contents, but also the attribute bits, file comments, dates and exact names of all items.
DirDiff can scan a directory or disk and give an electronic signature (for example "DD5-A89CE287"), derived from the contents of all files. This short code can then be used to refer to a particular disk or product release without detailing the entire contents. For example, two distant offices which want to verify if they have the same version of a disk can execute DirDiff separately, and then check the signature in a phone call taking only a few seconds. Or the signature can be used as a reference in a licensing agreement, as a confirmation of what is being licensed.
DirDiff includes additional checksum capabilities, and features such as clearing of unused blocks on a device (useful when it is desirable that others do not "undelete" data on a medium which was considered safe to give away).
This software is included with the Personal Suite. Version 5.1 is available in the Download section.