first commit

CRONS/lock.php

@@ -0,0 +1,43 @@
+<?php
+
+// sudo mkdir /run/php
+// sudo chmod a+rw /run/php
+ 
+function lock_pid_file($fn=NULL) {
+	if ($fn==NULL) {
+		$fn = '/run/php/'.basename($_SERVER['PHP_SELF'], '.php').'.pid';
+	}
+	$lock_file = fopen($fn, 'c');
+	$got_lock = flock($lock_file, LOCK_EX | LOCK_NB, $wouldblock);
+	if ($lock_file === false || (!$got_lock && !$wouldblock)) {
+    throw new Exception(
+        "Unexpected error opening or locking lock file. Perhaps you " .
+        "don't  have permission to write to the lock file or its " .
+        "containing directory?"
+    );
+	}
+	else if (!$got_lock && $wouldblock) {
+    exit("Another instance is already running; terminating.\n");
+	}
+	// Lock acquired; let's write our PID to the lock file for the convenience
+	// of humans who may wish to terminate the script.
+	ftruncate($lock_file, 0);
+	fwrite($lock_file, getmypid() . "\n");
+
+	/*
+    The main body of your script goes here.
+	*/
+	return $lock_file;
+}
+
+function unlock_pid_file($lock_file) {
+	// All done; we blank the PID file and explicitly release the lock 
+	// (although this should be unnecessary) before terminating.
+	ftruncate($lock_file, 0);
+	flock($lock_file, LOCK_UN);
+}
+
+/*
+vi:ts=2
+*/
+