Introduction

ulif.pynotify is a Python package that helps keeping track of changes in filesystem.

It therefore scans the filesystem starting at a given root and checks which of the found files were changed.

What does it mean that a file has changed? That depends on the filesystem scanner you are using. ulif.pynotify comes currently with two different scanners:

1. The plain scanner takes a path and a Unix timestamp as argument and then scans the given path (and all directories) for files and directories that were modified since the time given by the timestamp.
2. The pysqlite scanner is able to store scan results in an SQLite database and can therefore remember on second and further runs, which files/directories existed at a given prior point in time, which items were added or removed meanwhile.

All scanners can be deployed using the package API or a commandline script called pynotify.

Use of the API is explained in ulif.pynotify API.

Installing ulif.pynotify

You can install this package using easy_install or zc.buildout, optionally deploying virtualenv.

Requirements

• Python 2.x
• A C compiler like GCC if you want to use zc.buildout.

Using zc.buildout

The sources for released versions can be found on http://pypi.python.org/pypi/ulif.pynotify, the developer sources can be checked out via subversion from https://svn.gnufix.de/repos/main/ulif.pynotify.

Download the sources and eventually unpack them in a local directory. Change to that directory. Then, run:

$ python bootstrap/bootstrap.py
$ bin/buildout

This will generate scripts and directories in the local directory.

Using easy_install

If you don’t have easy_install already installed on your system, run:

$ wget http://peak.telecommunity.com/dist/ez_setup.py
$ python ez_setup.py

This will install easy_install in your $PATH.

If you’re using the system Python you need to perform the latter step as root user. If you want to install easy_install without root access, you can deploy virtualenv.

Afterwards, run:

$ easy_install ulif.pynotify

If the package is already installed on your system, you can update to the latest version by:

$ easy_install -U ulif.pynotify

easy_install will also install the pynotify commandline script.

Using the pynotify commandline script

The pynotify commandline script gives all options like this:

$ pynotify --help

If you call the script with a path only, it will display all files found in the respective directory:

$ pynotify some_dir /path/to/some_dir /path/to/some_dir/file1 /path/to/some_dir/file2

If you call the script with a timestamp (seconds since Unix epoch), it will display all files modified since then only:

$ pynotify -t 1285000000 some_dir
/path/to/some_dir/file1

If call the script with the --sqlite or -s option, the results will be stored in a local SQLite database:

$ pynotify -s some_dir
A /path/to/some_dir
A /path/to/some_dir/file1
A /path/to/some_dir/file2

Here we get a different output: The script tells us, that these files were (A)dded at the beginning of each line. This is normal for a first run on a directory. The following markers can appear:

A	file/directory added since last run of pynotify
M	file/directory modified since last run of pynotify
D	file/directory deleted since last run of pynotify

Unmodified files are not displayed. The scan results are stored in an SQLite database file pynotify.db in the local directory.

When we restart the script with the same options and from the same location, we normally will get no output until one file is modified. Afterwards we will see:

$ pynotify -s some_dir
M /path/to/some_dir/file1

If a file is deleted, this will also be noticed on further runs:

$ rm some_dir/file1
$ pynotify -s some_dir
D /path/to/some_dir/file1

If we want to make sure a certain database is used in runs, we can tell so by the --dbpath option:

$ pynotify -s --dbpath=/path/to/mydb.db some_dir
A /path/to/some_dir
A /path/to/some_dir/file1
A /path/to/some_dir/file2

If the database does not already exist, it will be created on first access attempt.