Package: infi.watchdog
Python API and shell utilities to monitor file system events.Example API UsageA 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)
    except KeyboardInterrupt:
        observer.stop()
    observer.join()Shell UtilitiesWatchdog comes with a utility script calledwatchmedo.
Please typewatchmedo--helpat the shell prompt to
know more about this tool.Here is how you can log the current directory recursively
for events related only to*.pyand*.txtfiles while
ignoring all directory events:watchmedo log \
    --patterns="*.py;*.txt" \
    --ignore-directories \
    --recursive \
    .You can use theshell-commandsubcommand 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] --helpAboutwatchmedoTrickswatchmedocan readtricks.yamlfiles and execute tricks within them in
response to file system events. Tricks are actually event handlers that
subclasswatchdog.tricks.Trickand are written by plugin authors. Trick
classes are augmented with a few additional features that regular event handlers
don’t need.An exampletricks.yamlfile: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 thetricks.yamlfile will be monitored. Each trick
class is initialized with its corresponding keys in thetricks.yamlfile as
arguments and events are fed to an instance of this class as they arrive.Tricks will be included in the 0.5.0 release. I need community input about them.
Please file enhancement requests at theissue tracker.InstallationInstalling from PyPI usingpip:pip install watchdogInstalling from PyPI usingeasy_install:easy_install watchdogInstalling from source:python setup.py installInstallation CaveatsThewatchmedoscript depends onPyYAMLwhich links withLibYAML,
which brings a performance boost to the PyYAML parser. However, installingLibYAMLis optional but recommended. On Mac OS X, you can usehomebrewto install LibYAML:brew install libyamlOn Linux, use your favorite package manager to install LibYAML. Here’s how you
do it on Ubuntu:sudo aptitude install libyaml-devOn Windows, please installPyYAMLusing the binaries they provide.DocumentationYou can browse the latest releasedocumentationonline.Supported PlatformsLinux 2.6 (inotify)Mac OS X (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~/.profilefile and add
a line similar to:ulimit -n 1024This 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.About using watchdog with editors like VimVim 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 to appropriately to disable
this feature.DependenciesPython 2.5 or above.XCode(only on Mac OS X)PyYAMLarghselect_backport(select.kqueue replacement for Python2.5/2.6 on BSD/Mac OS X)pathtoolsLicensingWatchdog is licensed under the terms of theApache License, version 2.0.Copyright 2011Yesudeep Mangalapilly.Copyright 2012 Google, Inc.Projectsource codeis available at Github. Please report bugs and file
enhancement requests at theissue tracker.Why Watchdog?Too many people tried to do the same thing and none did what I needed Python
to do:pnotifyunison fsmonitorfsmonitorguardpyinotifyinotify-toolsjnotifytreewalkerfile.monitorpyfilesystem