write PID to file

dataLogger.py

@@ -9,6 +9,8 @@ from pycomm_helper.alarm import AnalogAlarm, bitAlarm
 import traceback
 import json
 import requests
+import os
+import sys
 
 from requests.packages.urllib3.exceptions import InsecureRequestWarning
 from requests.packages.urllib3.exceptions import InsecurePlatformWarning
@@ -16,6 +18,7 @@ from requests.packages.urllib3.exceptions import InsecurePlatformWarning
 requests.packages.urllib3.disable_warnings(InsecureRequestWarning)
 requests.packages.urllib3.disable_warnings(InsecurePlatformWarning)
 
+
 # DEFAULTS
 API_METHOD = "https"
 API_ADDRESS = "localhost"
@@ -316,4 +319,16 @@ def main():
             print("Error during loop: {}".format(e))
             traceback.print_exc()
 if __name__ == '__main__':
-    main()
+    pid = str(os.getpid())
+    pidfile = "/root/datalogger.pid"
+
+    if os.path.isfile(pidfile):
+        print "%s already exists, exiting" % pidfile
+        sys.exit()
+
+    try:
+        file(pidfile, 'w').write(pid)
+        main()
+    except IOError:
+        print("Unable to write the PID to {}. Running the datalogger anyway.".format(pidfile))
+        main()