Python API and shell utilities to monitor file system events.
Works on 3.6+.
A simple program that uses watchdog to monitor directories specified as command-line arguments and logs events generated:
import sys
import time
import logging
from watchdog.observers import Observer
from watchdog.events import LoggingEventHandler
if __name__ == "__main__":
logging.basicConfig(level=logging.INFO,
format='%(asctime)s - %(message)s',
datefmt='%Y-%m-%d %H:%M:%S')
path = sys.argv[1] if len(sys.argv) > 1 else '.'
event_handler = LoggingEventHandler()
observer = Observer()
observer.schedule(event_handler, path, recursive=True)
observer.start()
try:
while True:
time.sleep(1)
finally:
observer.stop()
observer.join()Watchdog comes with an optional utility script called watchmedo.
Please type watchmedo --help at the shell prompt to
know more about this tool.
Here is how you can log the current directory recursively
for events related only to *.py and *.txt files while
ignoring all directory events:
watchmedo log \
--patterns="*.py;*.txt" \
--ignore-directories \
--recursive \
--verbose \
.You can use the shell-command subcommand to execute shell commands in
response to events:
watchmedo shell-command \
--patterns="*.py;*.txt" \
--recursive \
--command='echo "${watch_src_path}"' \
.Please see the help information for these commands by typing:
watchmedo [command] --helpwatchmedo can read tricks.yaml files and execute tricks within them in
response to file system events. Tricks are actually event handlers that
subclass watchdog.tricks.Trick and are written by plugin authors. Trick
classes are augmented with a few additional features that regular event handlers
don't need.
An example tricks.yaml file:
tricks:
- watchdog.tricks.LoggerTrick:
patterns: ["*.py", "*.js"]
- watchmedo_webtricks.GoogleClosureTrick:
patterns: ['*.js']
hash_names: true
mappings_format: json # json|yaml|python
mappings_module: app/javascript_mappings
suffix: .min.js
compilation_level: advanced # simple|advanced
source_directory: app/static/js/
destination_directory: app/public/js/
files:
index-page:
- app/static/js/vendor/jquery*.js
- app/static/js/base.js
- app/static/js/index-page.js
about-page:
- app/static/js/vendor/jquery*.js
- app/static/js/base.js
- app/static/js/about-page/**/*.jsThe directory containing the tricks.yaml file will be monitored. Each trick
class is initialized with its corresponding keys in the tricks.yaml file as
arguments and events are fed to an instance of this class as they arrive.
Install from PyPI using pip:
$ python -m pip install -U watchdog
# or to install the watchmedo utility:
$ python -m pip install -U "watchdog[watchmedo]"Install from source:
$ python -m pip install -e .
# or to install the watchmedo utility:
$ python -m pip install -e ".[watchmedo]"The watchmedo script depends on PyYAML which links with LibYAML,
which brings a performance boost to the PyYAML parser. However, installing
LibYAML is optional but recommended. On macOS, you can use homebrew
to install LibYAML:
$ brew install libyamlOn Linux, use your favorite package manager to install LibYAML. Here's how you do it on Ubuntu:
$ sudo apt install libyaml-devOn Windows, please install PyYAML using the binaries they provide.
You can browse the latest release documentation online.
Fork the repository on GitHub and send a pull request, or file an issue ticket at the issue tracker. For general help and questions use the official mailing list or ask on stackoverflow with tag python-watchdog.
Create and activate your virtual environment, then:
python -m pip install pytest pytest-cov python -m pip install -e ".[watchmedo]" python -m pytest tests
If you are making a substantial change, add an entry to the "Unreleased" section of the changelog.
- Linux 2.6 (inotify)
- macOS (FSEvents, kqueue)
- FreeBSD/BSD (kqueue)
- Windows (ReadDirectoryChangesW with I/O completion ports; ReadDirectoryChangesW worker threads)
- OS-independent (polling the disk for directory snapshots and comparing them periodically; slow and not recommended)
Note that when using watchdog with kqueue, you need the
number of file descriptors allowed to be opened by programs
running on your system to be increased to more than the
number of files that you will be monitoring. The easiest way
to do that is to edit your ~/.profile file and add
a line similar to:
ulimit -n 1024
This is an inherent problem with kqueue because it uses file descriptors to monitor files. That plus the enormous amount of bookkeeping that watchdog needs to do in order to monitor file descriptors just makes this a painful way to monitor files and directories. In essence, kqueue is not a very scalable way to monitor a deeply nested directory of files and directories with a large number of files.
Vim does not modify files unless directed to do so. It creates backup files and then swaps them in to replace the files you are editing on the disk. This means that if you use Vim to edit your files, the on-modified events for those files will not be triggered by watchdog. You may need to configure Vim appropriately to disable this feature.
When you want to watch changes in CIFS, you need to explicitly tell watchdog to
use PollingObserver, that is, instead of letting watchdog decide an
appropriate observer like in the example above, do:
from watchdog.observers.polling import PollingObserver as Observer
Watchdog is licensed under the terms of the Apache License, version 2.0.
Copyright 2011 Yesudeep Mangalapilly.
Copyright 2012 Google, Inc & contributors.
Project source code is available at Github. Please report bugs and file enhancement requests at the issue tracker.
Too many people tried to do the same thing and none did what I needed Python to do: