Source URL: https://www.bttr-software.de/freesoft/antivir.htm

MD5SUM — Calculate and verify MD5 hash values for files.

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[added 2000-08-09, updated 2005-12-09]

This program, originally for Unix, will calculate an MD5 value for a given file and also allows you to check the values against an existing, valid value to determine if the file has been changed/corrupted. MD5SUM is most often used to validate the integrity of transferred files which have a reference MD5 value stored on the server. But I employ it as a cheap, antiviral "checksum comparer" for files on my local hard drive. 16-bit program, w/ source in package.

As a simple usage example, first generate a file (TEST.MD5) holding a baseline MD5 value for a given file (MY.ZIP):

MD5SUM -b MY.ZIP >TEST.MD5
(-b: assume binary file). To check the MD5 value of the file at a later date (or to validate copy of file) use,
MD5SUM -b -c TEST.MD5
If the values match, output will be:
"C:\MY.ZIP: OK"
If new value doesn't match:
"C:\MY.ZIP: FAILED"
Notes: MD5SUM doesn't accept wildcards – if you want to obtain many file values at once, write an appropriate batch file. For an entire drive, you could use an easy batch helper like Locate to collect baseline values, e.g., all *.exe files on drive C, write a batch similar to:

locate C:*.exe /o:"MD5SUM -b &F>>BASELN.MD5"> MD5DRV.BAT
Run MD5DRV.BAT at any time, or just replace the  /o  switch above with  /c  to execute immediately.
Run
MD5SUM -c BASELN.MD5
after MD5DRV.BAT, to compare later values against baselines.
Authors: Branko Lankester, Netherlands; Colin Plumb, Canada (1993). Compilation & docs by Michael Paul Johnson (1995, 2000).

Versions       	
1995-02-04:	
Unnumbered release
2000-08-14:	
Revised documentation
Download md5sum.zip (34K). ftp://ebible.org/pub/public/md5sum.zip

For a 32-bit version w/ Win9x LFN support, see GNU Textutils – Summarizing Files.