md5i - yet another MD5 file integrity checker

This Java program creates an MD5 database of all files in a directory structure, and then allows you to easily recheck the contents of the directory and notify you if any files has changed. It does not (currently) detect removed files. It only computes MD5 sum if the "last modified" timestamp of the file has changed since the last run, unless the -nomtime option is used.

Sample usage (Windows)

(Using the "md5.bat" script)

C:\md5itest>echo foobar > c:\tmp\foobar

C:\md5itest>md5i -scan c:\tmp

C:\md5itest>md5i -check c:\tmp

C:\md5itest>echo gazonk > c:\tmp\foobar

C:\md5itest>md5i -check c:\tmp
[NOT OK] c:\tmp\foobar
Old MD5: 5e963b88334c3c4487572cce68496989
New MD5: 4fec417bec4554de6c345df96b084e96
Old timestamp: Wed Dec 22 13:04:49 CET 2004
New timestamp: Wed Dec 22 13:05:35 CET 2004
Action: I=ignore, U=update database (default: I)?  u

C:\md5itest>md5i -check c:\tmp



md5i [-db <file>] [-v] [-nomtime] [[-updatedb] -scan <dir>] [[-alwaysignore] -check]

Generic options:
         -db FILE       uses FILE to store file data (default: ~/.md5database)
         -v             verbose: outputs progress information
         -nomtime       ignore file timestamps

Scan options:
         -scan DIR      scans DIR and all sub-directories
         -updatedb      updates the database instead of creating a new

Check uptions
         -check DIR     checks all files in DIR and its sub-directories
         -alwaysignore  Don't prompt on modified files: only report and ignore      

Download and use

A file containing the compiled Java code and Windows and Unix wrapper scripts can be downloaded here:
The source can be downloaded here: md5i-src-20041222.tar
The file md5i is the Unix wrapper script and md5i.bat is for Windows. The Unix shell script checks for $JAVA_HOME while the Windows batch file assumes that the java.exe executable is in your %PATH%. Also, on Unix you'll have to "chmod +x md5i" first and if you want to be able to run it from other locations, you'll have to edit the script to set JARPATH to the location of the md5i.jar file. The program will always exit with a non-zero exit code if any files has been modified.

GUI version

The good thing about commuting by train is that you basically have a lot of time that you spend being very bored. And boredom fosters creativity. Sort of. So during the trip home from Stockholm, I hacked this extremely bare-bones GUI for MD5i. I have only made a Java Web Start package of it, so far. As with my other GUI applications, it works on Windows and probably Linux. Launch it by clicking the link below:

Start MD5i GUI

To use, first chose a folder and then click "Build database". On subsequent runs, you click "Check" to check if the folder contents has changed.
Screenshots: main dialog, notification that a file has been changed.


Many, I'm sure. No warranties, yada yada.


Rasmus Sten created this after a suggestion from Santeri. There are many other improvements that can be done. For example, the use of a faster MD5 implementation (as in Duper) would speed up things considerably. The code is free to do whatever you want with. If you want to build a GUI, check out the main() method on the MD5Integrity class, which demonstrates what has to be done.