Module Daemon

module Daemon: Daemon

type redirect_fds = [ `Dev_null
       | `Do_not_redirect
       | `File_append of string
       | `File_truncate of string ] 

val daemonize : ?redirect_stdout:redirect_fds ->
       ?redirect_stderr:redirect_fds ->
       ?cd:string -> ?umask:int -> unit -> unit

daemonize ?(redirect_stdout=`Dev_null) ?(redirect_stderr=`Dev_null) ?(cd = "/") ?umask=[0] () makes the current executing process a daemon, and dups "/dev/null", redirect_stdout, redirect_stderr to stdin/stdout/stderr. redirect_stdout and redirect_stderr default to /dev/null. See Chapter 13 of Advanced Programming in the UNIX Environment Second Edition by Stephens and Rago for more details.
Raises Failure if fork was unsuccessful.

val daemonize_wait : ?redirect_stdout:redirect_fds ->
       ?redirect_stderr:redirect_fds ->
       ?cd:string -> ?umask:int -> unit -> unit -> unit

daemonize_wait ?(cd = "/") ?(umask=0) () makes the executing process a daemon, but delays full detachment from the calling shell/process until the returned "release" closure is called.

Any output to stdout/stderr before the "release" closure is called will get sent out normally. After "release" is called, "/dev/null", redirect_stdout, and redirect_stderr gets dup'd to stdin/stdout/stderr. redirect_stdout and redirect_stderr default to /dev/null.

Note that calling release will adjust SIGPIPE handling, so you should not rely on the delivery of this signal during this time.

daemonize_wait allows you to daemonize and then start async, but still have stdout/stderr go to the controlling terminal during startup. By default, when you daemonize, toplevel exceptions during startup would get sent to /dev/null. With daemonize_wait, toplevel exceptions can go to the terminal until you call release.
Raises Failure if fork was unsuccessful.