script to watch a bunch of files and run a command if any changes are detected.

docs/watcher.py

@@ -0,0 +1,62 @@
+"""
+Watch a bunch of files and run a command if any changes are detected.
+
+Usage
+-----
+::
+
+    python watcher.py 'echo changes' one.py two.py
+
+To automatically keep Sphinx docs up to date::
+
+    python watcher.py 'make html' $(find . -name '*.rst')
+
+Problems
+--------
+
+ * The file checking would be way more efficient using inotify or whatever the
+   equivalent is on OS X.
+ * It doesn't handle bad input or spaces in filenames.
+
+But it works for me.
+"""
+import os
+import sys
+import time
+
+
+_mtimes = {}
+
+
+def timecheck(files):
+    """Return True if any of the files have changed."""
+    global _mtimes
+    for filename in files:
+        mtime = os.stat(filename).st_mtime
+        if filename not in _mtimes:
+            _mtimes[filename] = mtime
+        elif mtime != _mtimes[filename]:
+            _mtimes = {}
+            return True
+    else:
+        return False
+
+
+def watcher(command, files):
+    """Run ``command`` if any file in ``files`` changes."""
+    while True:
+        if timecheck(files):
+            os.system(command)
+        time.sleep(1)
+
+
+def main():
+    command, files = sys.argv[1], sys.argv[2:]
+    try:
+        watcher(command, files)
+    except KeyboardInterrupt:
+        pass
+
+
+if __name__ == '__main__':
+    main()