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Potential Virus[edit]

This article links to an external .exe file at the bottom, with no proper explanation. I sication submission, and that this is an attempt to trick those looking for the solution to the problem. Upon downloading the file, my virus checker did not detect any threat from it, but executing the file does nothing special, and the source of the file is also questionable. — Preceding unsigned comment added by SargerasReborn (talkcontribs) 15:28, 12 April 2011 (UTC)

I removed the link. —Preceding unsigned comment added by (talk) 18:41, 20 April 2011 (UTC)
Linking .exe files from wikipedia articles is bad practice. Would be nice if wikimedia software automatically blocked those links. Jaho (talk) 18:52, 12 September 2011 (UTC)

What MD5 stands for[edit]

What does md5 stand for?

From MD5: MD5 (Message-Digest algorithm 5)
Also see RFC 1321. --Teratornis 19:26, 22 January 2007 (UTC)

Qualifying the "exact copy" claim[edit]

Two non-identical files have a very low but non-zero probability of generating the same MD5 hash. I clarified this in Md5sum#Usage, which previously stated that if two copies of a file produce the same MD5 hash, they must be identical. That is virtually always true but is not absolutely guaranteed to be true. This is trivially easy to recognize from the fact that there are more possible files than MD5 hashes, because MD5 hashes have a fixed length, and files can be of any length. See RFC 1321 for more about the computational effort of constructing two non-identical files with the same MD5 hash (and thus something about the probability that two randomly-chosen non-identical files will have the same MD5 hash). --Teratornis 19:26, 22 January 2007 (UTC)

How does it work?[edit]

Perhaps more description about the summing process itself instead of glossing over it's purpose and then giving a usage synopsis. —Preceding unsigned comment added by Memotype (talkcontribs) 16:25, 26 September 2007 (UTC)

The requested information is in MD5, which is a more logical place, and properly linked from this article. Jaho (talk) 18:46, 12 September 2011 (UTC)
Unfortunately, the MD5 article I looked at is only about encrypting a string, and does not say how to generate the string to encrypt from a file. I think it has something to do with reading each byte of a file and MD5ing those bytes... somehow... I'm not really sure ... if only there were an explanation here of the standard for how to generate what is MD5ed when making a file checksum, I would know! Maybe a brief explanation of what is done next (i.e. an algorithm combines all the bytes in an array of bytes down to a 128 bit string) with a link to a more detailed explanation in the MD5 article. — Preceding unsigned comment added by (talk) 19:05, 19 April 2015 (UTC)

Broken Link[edit]

Anyone have a new link to md5-paper.pdf? Should it be removed? JohnMccabeDansted (talk) 17:30, 28 January 2008 (UTC)

The current tag stating "This article reads like a man-page"[edit]

I personally don't think that this article reads like a man page (even though it does give a few usage examples) and, unfortunately, the editor who added the tag left no suggestions on the talk page (he or she was editing from an IP address, so it is doubtful he or she could be contacted about it).  :-( I am inclined to remove it. What do others think? --Iamunknown 20:52, 16 February 2008 (UTC)

Made easier usage examples[edit]

The usage examples which were there before assumed that the person knows what he's doing. Hence added couple of usage examples which will make it easier for newbies to do the same. If anybody has any issues, please connect with me before deleting/changing the same. [[User:Shirishag75|Shirishag75]] (talk) 07:32, 16 March 2008 (UTC)

Wikipedia is not a repository for how-to information[edit]

Sorry folks, but how-to info should go elsewhere. The "usage examples" were more than usage examples - they smacked of how-to. As most of this article was howto - and blatantly read like a howto ("you can run this command," "you can just do this with these arguments," etc.) - I felt compelled to axe most of the article. The usage examples weren't really of much use in explaining the program or its point per se. Tjvanwyk (talk) 22:11, 13 April 2008 (UTC)

I don't know what the suppressed examples looked like : but I dare say, Wikipedia is NOT an expert-only project. It HAS TO be readable by ordinary, non expert, people !!! Ptyxs (talk) 21:05, 20 April 2011 (UTC)
Removed the excessive and irrelevant examples (leaving two basic ones). Removed the {example farm} tag. Jaho (talk) 18:56, 12 September 2011 (UTC)

External Links[edit]

1. Started this section to discuss external links.

2. Reviewed the existing external links and have added a link to MD5 Command Line Message Digest Utility link. The page has been around for years, is stable, and updated. The program itself (both Windows and Linux) are stable as well. A good overall resource. —Preceding unsigned comment added by (talk) 19:37, 18 July 2008 (UTC)

wrong statement[edit]

The article says "it is not possible to compute a checksum for an entire directory. You have to recursively check every single file", but this is wrong! On my system md5sum calculates a checksum for a directory, just with "md5sum * > file.md5", and checks with "md5sum -c file.md5" —Preceding unsigned comment added by (talk) 22:47, 24 November 2010 (UTC)


Someone needs to translate this article into English. "find directory -type f -print0 | xargs -0 md5sum >> file.md5" is unintelligible to the vast majority of English speakers. James Galloway (talk) 19:13, 30 November 2010 (UTC)

I disagree. There are countless articles in other fields such as chemistry and mathematics that have examples that are not necessarily readable by the vast majority of English speakers. Take, for example, the article on Pyridine. There are formulas and reactions there that are "unintelligible" to an average English speaker. The use of the "find" commands referenced in the article are probably at the same level of complexity as most of the chemical reaction formulas I've come across. Johnson.eric.d (talk) 16:06, 3 June 2011 (UTC)

Possibly there's an error in the usage examples (?)[edit]

I'm wondering what the -s option in the usage examples stands for (find -s ...). Maybe the examples refer to an outdated version of find, because I tried on three different systems that claim to be POSIX compliant, and on none of them the -s option was recognized. BR Bert (talk) 20:26, 11 July 2011 (UTC)

-s Cause find to traverse the file hierarchies in lexicographical order, i.e., alphabetical order within each directory. Note: ‘find -s’ and ‘find | sort’ may give different results. This may not be POSIX.

Proposed merge with Sha1sum[edit]

These are basically the same article. On many systems the programs are even hardlinks to each other! Voomoo (talk) 04:01, 5 July 2014 (UTC)


Should be MD5sum. 2602:306:CDE5:5090:59A5:F276:AB51:3AEE (talk) 01:42, 20 July 2016 (UTC)