same: a tool to find duplicate lines of code - Revived Java code
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same: a tool to find duplicate lines of code

"Mechanical means can't prove good code, but they can often prove bad code.""

This is the beginning of a nifty tool to combat Copy & Paste attacks.

Some example output showing places in pry that are duplicated. Note that this is with the default settings. Here are the options:


  • -f filter filter all files with this filter (none, trim, baan, java)
  • -m minimalSize minimal fragment length [default: 10]

The trim filter is especially useful, since much duplication gets indented/outdented immediately after copy and pasting. The same script actualy defaults this to on, but you can override it with -f none (though I doubt you'll ever really want to).

There should be more filters (and rewriting this from Java would make better filtration possible.) For now, you can rely on VCS and do like this (using zsh's recursive globbing):

sed -i 's/\s*end//' **/*.rb
same -m 3 **/*.rb
git checkout .

See how it uses a more aggressive -m limit. This can be very informative, but it's usually nice to start with the default of 10 then zoom in from there. You can also benefit from -m 1, but it takes good pre-filtering.


You have to have a Java Runtime Environment. For Gentoo, I emerged dev-java/icedtea-bin, and for SuSE Linux I installed java-1_6_0-openjdk. OS X comes with one by default as far as I know.


Currently, it has this odd deal where the file has to live in the same dir as the same script. Here's a quick way to get it to work:

cp bin/* ~/bin/

Or, you can just run it from the cloned dir, e.g.:

cd ~/src
git clone
cd my-proj
~/src/same/bin/same **/*.c

So that means you could, in your ~/.bashrc or ~/.zshrc:

alias same=~/src/same/bin/same

Note that I (☈king) am no Java pro, so if you have any problems, I'd love to help walk you through them and make this README better. Or, of course, if you are the Java pro, I'd like to hear about best practices for deploying a script like this.


This software is open source, under the GNU Public License. See GPL.txt.


Huge thanks to Marnix Klooster, who wrote the original. This is his Thanks:

Thanks to Baan for giving me the opportunity to write this software, and to make it open source.

All feedback is welcome at

Groetjes, <>< Marnix

Marnix Klooster