What is MD5?

MD5 refers to the MD5 Message Digest Algorithm∞. MD5 hashes are often used to check if a file downloaded correctly, if the MD5 hashes are different, then the file is corrupted or a different version. A MD5 hash (or checksum) is typically a 32-character hexadecimal number that can result from running the md5sum program against a particular file. Since any difference between two files results in two different values, MD5 values can be used to determine that the file (e.g. puppy-release.iso) you downloaded is an exact copy of the original file. The file with the MD5 value usually has the same name as the file you downloaded, but it ends with an additional .md5 and/or .txt extension (e.g. puppy-release.iso.md5.txt).

(An MD5 check is not necessary with a BitTorrent download as Bitttorrent automatically checks and corrects any errors.)

Verify MD5 checksum using Linux or DOS:

Type (in the same directory where the files are and using the actual filename):
md5sum -c puppy-release.iso.md5.txt

If you're using DOS or DOS-based versions of Windows (Windows 95, 98 & ME included) you can use this MS-DOS compatible application (only 48K): md5sum.exe∞. Right-click on the file name and save it to the folder that your downloaded file is in.

Create a MD5 checksum file using the standard command line utility:

Type: md5sum puppy-puplet.iso > puppy-puplet.iso.md5

For more see the md5sum documentation∞.

MD5sums for Windows∞

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