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`hdaemonize-0.4.3` ================= `hdaemonize` is a simple library that hides some of the complexities of writing UNIX daemons in Haskell. Obtaining ----------- The latest version is available (BSD license) at [GitHub](https://github.com/madhadron/hdaemonize). Using ------- The synopsis is: import System.Posix.Daemonize main = daemonize $ program This code will make `program` do what good daemons should do, that is, detach from the terminal, close file descriptors, create a new process group, and so on. If you want more functionality than that, it is available as a `serviced` function. Here is an example: import Control.Concurrent import System.Posix.Daemonize loop i log = do threadDelay $ 10^6 log (show i) writeFile "/tmp/counter" $ show i if i == 5 then undefined else loop (i + 1) log main = serviced (loop 0) Let us say this program is compiled as `mydaemon`. Then: # mydaemon start starts the service. A second call to start will complain that the program is already running. During its execution, mydaemon will simply write a new number to `/tmp/counter` every second, until it reaches 5. Then, an exception will be thrown. This exception will be caught by `hdaemonize`, and logged to `/var/log/daemon.log` or similar (this is depends on how `syslog` works on your platorm). `log (show i)` will leave messages in the same file. When the exception is thrown, the program will be restared in 5 seconds, and will start counting from 0 again. The following commands are also made available: # mydaemon stop # mydaemon restart Finally, `mydaemon` drops privileges. By default it changes the effective user and group ids to those of the `daemon` user, but it prefers to use those of `mydaemon`, if present. Changelog --------- * 0.4 * added support for a privileged action before dropping privileges * 0.3 * merged with updates by madhadron * 0.2 * provided documentation * backported to older GHC versions, tested on 6.8.1 * 0.1 * initial public release Authors ------- Anton Tayanovskyy <firstname.lastname@example.org>, bug reports and feature requests welcome. The code is originally based on a public posting by [Andre Nathan](http://sneakymustard.com/), used by permission.