-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | utilities for UNIX daemon writing
--   
--   Provides two functions that help writing better UNIX daemons,
--   daemonize and serviced: daemonize does what a daemon should do
--   (forking and closing descriptors), while serviced does that and more
--   (syslog interface, PID file writing, start-stop-restart command line
--   handling, dropping privileges).
@package hdaemonize
@version 0.2

module System.Posix.Daemonize

-- | The simplest possible interface to syslog.
type Logger = String -> IO ()

-- | A program is any IO computation. It also accepts a syslog handle.
type Program = Logger -> IO ()

-- | Daemonizes a given IO computation by forking twice, closing standard
--   file descriptors, blocking sigHUP, setting file creation mask,
--   starting a new session, and changing the working directory to root.
daemonize :: IO () -> IO ()

-- | Turns a program into a UNIX daemon (system service) ready to be
--   deployed to <i>etc</i>rc.d or similar startup folder. The resulting
--   program handles command-line arguments (start, stop, or restart).
--   
--   With start option it writes out a PID to <i>var</i>run/$name.pid where
--   $name is the executable name. If PID already exists, it refuses to
--   start, guaranteeing there is only one live instance.
--   
--   With stop option it reads the PID from <i>var</i>run/$name.pid and
--   terminates the corresponding process (first a soft kill, SIGTERM, then
--   a hard kill, SIGKILL).
--   
--   Another addition over the daemonize function is dropping privileges.
--   If a system user and group with a name that matches the executable
--   name exist, privileges are dropped to that user and group. Otherwise,
--   they are dropped to the standard daemon user and group.
--   
--   Finally, exceptions in the program are caught, logged to syslog, and
--   the program restarted.
serviced :: Program -> IO ()