snappify

snappify is used to create and maintain directory snapshots. It includes a number of low-level utlities and a high-level wrapper.

Create a snapshot

Creating a snapshot is as easy as changing to the directory you want to take a snapshot of and running snappify init then snappify snap.

# cd /home/user
# snappify init
initializing snappify repository in /home/user/.snappify
# snappify snap
created snapshot 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83

4e1243bd22c66e76c2ba9eddc1f91394e57f9f83 is the randomly generated ID of the snapshot that is used to reference the snapshot in other actions. You can create a more friendly reference to the snapshot by creating an alias.

# snappify alias foo 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
foo -> 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83

When creating the snapshot, you can also specify an alias.

# snappify snap foo
created snapshot 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83 (foo)

A special alias last always references the last snapshot created. snappify alias will show you all the aliases.

# snappify alias
last -> 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83
foo -> 4e1243bd22c66e76c2ba9eddc1f91394e57f9f83

In lieu of an alias, snapshots can also be referenced by partial IDs. For example, the above snapshot could be referenced as 4e12. There is no limit to how few characters to use. Be aware, however, that if two snapshots match the partial ID, the newest one will be used. You can use snappify-alias to determine which snapshot will be used for a given partial ID.

# snappify alias 4e12
4e1243bd22c66e76c2ba9eddc1f91394e57f9f83

Checking for changes

A summary of the changes made since the last snapshot can be viewed using snappify status. It will display whether files are new (n), modified (m) or deleted (d).

# rm temp.txt
# snappify status
d temp.txt
# snappify status 7b82
d temp.txt
m bar.txt

If no snapshot is specified, last is assumed.

You can see the changes that have been made to each file using snappify diff. This will produce a diff for each file that has changed. If no snapshot is defined, last is assumed.

# snappify diff
--- /home/user/.snappify/snaps/1feed73104b827183ac3eddb290012cc3d3c532a/bar.txt  2013-02-23 23:31:04.000000000 -0800
+++ /home/user/bar.txt  2013-02-25 13:39:11.520759306 -0800
@@ -0,0 +1,2 @@
+Hello world!
+Hello again!

You can see the changes for a specific file by specifying it.

# snappify diff bar.txt

To see the changes for files since an older snapshot, specify the snapshot.

# snappify diff 4e12
..or..
# snappify diff 4e12 bar.txt

Restoring a snapshot

To restore a snapshot, run snappify restore and pass the snapshot ID or a valid alias.

# snappify restore foo

If no snapshot is specified, the snapshot reference by the last alias will be used.

# ls
helloWorld.txt        bar.txt
# snappify snap
created snapshot 9054fbe0b622c638224d50d20824d2ff6782e308
# rm helloWorld.txt
# ls
bar.txt
# snappify restore
restored snapshot 9054fbe0b622c638224d50d20824d2ff6782e308 into /snapshot/directory
# ls
helloWorld.txt        bar.txt

Snapshot storage

Running snappify init creates a new directory called .snappify in the current directory. All snapshots are stored within the .snappify directory. This directory is called the repository. Over time, the repository may accumulate a lot of snapshots. To refresh the repository you can run snappify clean, which will delete all the snapshots. You can list all the snapshots in the repository by running snappify list.

# snappify list
2013-02-22.15:02:38 8404516183a4734a7965e0a6fcf829c71f0b0cda /home/user
2013-02-23.13:38:56 9343d53a70a4be629ffa662b3b6cce3bcbc9005d /home/user
2013-02-25.17:30:21 1feed73104b827183ac3eddb290012cc3d3c532a /home/user
# snappify clean
# snappify list