Add the Unix module and enable daemonization.

[dead/halcyon.git] / src / ExitCodes.hs

diff --git a/src/ExitCodes.hs b/src/ExitCodes.hs
index 7597a54723e0fa28d466f195f5161e60698ea3c4..65a519869cf3f88ecfa86c64c0353b4d0c9c4553 100644 (file)
--- a/src/ExitCodes.hs
+++ b/src/ExitCodes.hs
@@ -1,9 +1,20 @@
 -- | All exit codes that the program can return (excepting
 --   ExitSuccess).
-module ExitCodes ( exit_no_usernames )
+module ExitCodes (
+  exit_no_usernames,
+  exit_pidfile_exists )
 where
 
+
 -- | No usernames found on either the command-line or in a config
 --   file.
 exit_no_usernames :: Int
 exit_no_usernames = 1
+
+
+-- | When running as a daemon, the existence of a fixed PID file is
+--   used to determine whether or not the daemon is already
+--   running. If the PID file already exists, we shouldn't start.
+--
+exit_pidfile_exists :: Int
+exit_pidfile_exists = 2