morenines: A simple content change detector

morenines hashes your files and, later, can tell you if they have changed.

Much like Git, information about your files is stored in a repository, in a hidden directory named .morenines.

To start using morenines, you initialize a repository and then add paths to it. Later, you can verify that your files have not changed.

Morenines does not modify your files. It just tells you if they have changed.

Short Usage

$ cd ~/photos
$ mn init .
SUCCESS: Initialized empty morenines repository in /home/mnuser/photos/.morenines
$ mn add 2016/camping_trip
SUCCESS: Files added to repository:
  2016/camping_trip/DSC0003.jpg
  2016/camping_trip/DSC0003.jpg
  2016/camping_trip/DSC0003.jpg

# (time passes...)
$ mn status --verify
Changed files (hash differs from index):
  2016/camping_trip/DSC0003.jpg

If you haven't edited it, a JPEG should not change. So now you know that you need to restore DSC0003.jpg from a backup.

Usage

Starting out

We have some files.

$ cd ~/photos
$ ls -1
DSC0001.jpg
DSC0002.jpg
TEMPFILE.dat
notes.txt

Let's track those files. First, initialize the repository:

$ mn init
SUCCESS: Initialized empty morenines repository in /home/mnuser/photos/.morenines

And then, add the files to the repository:

$ mn add DSC0001.jpg DSC0002.jpg TEMPFILE.dat notes.txt
SUCCESS: Files added to repository:
  DSC0001.jpg
  DSC0002.jpg
  TEMPFILE.dat
  notes.txt

Adding and removing files

Now the files are tracked in the repository by their content. We can get the status of the repository:

$ mn status
Index is up-to-date (no changes)

If we add a file, we can then run mn status to see the change:

$ echo "a new file" > new_file.txt
$ mn status
New files (not in index):
  new_file.txt

We can add the new file:

$ mn add new_file.txt 
SUCCESS: Files added to repository:
  new_file.txt

Note that this does not do anything to new_file.txt; it merely reads new_file.txt, computes information about it, and stores that information in the repository.

We can also use status to seesee if a file is missing:

$ rm TEMPFILE.dat 
remove TEMPFILE.dat? y
$ mn status
Missing files:
  TEMPFILE.dat

If this is intentional, we can tell morenines to forget about that file:

$ mn remove TEMPFILE.dat
SUCCESS: Files removed from repository:
  TEMPFILE.dat

Note that this does not do anything to TEMPFILE.dat; it merely removes the information about TEMPFILE.dat from the repository.

Detecting changed files

Here's the meat of it. We can use the --verify option of the status command to re-hash the tracked files and see if their content has changed:

$ echo "some new content" >> notes.txt 
$ mn status
Index is up-to-date (no changes)
$ mn status --verify
Changed files (hash differs from index):
  notes.txt

Now you know that the content of notes.txt has changed. If this is unexpected, you know that you need to restore notes.txt from a backup.

If it was expected, however, you can communicate this to morenines by using remove and then add on that path:

$ mn remove notes.txt
SUCCESS: Files removed from repository:
  notes.txt
$ mn add notes.txt
SUCCESS: Files added to repository:
  notes.txt