Proc::Daemon

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Daemon(3)	     User Contributed Perl Documentation	    Daemon(3)



NAME
       Proc::Daemon - Run Perl program as a daemon process

SYNOPSIS
	   use Proc::Daemon;
	   Proc::Daemon::Init;

DESCRIPTION
       This module contains the routine Init which can be called by a Perl
       program to initialize itself as a daemon.  A daemon is a process that
       runs in the background with no controlling terminal.  Generally
       servers (like FTP and HTTP servers) run as daemon processes.  Note, do
       not make the mistake that a daemon == server.

       The Proc::Daemon::Init function does the following:

       1   Forks a child and exits the parent process.

       2   Becomes a session leader (which detaches the program from the con-
	   trolling terminal).

       3   Forks another child process and exits first child.  This prevents
	   the potential of acquiring a controlling terminal.

       4   Changes the current working directory to "/".

       5   Clears the file creation mask.

       6   Closes all open file descriptors.

       You will notice that no logging facility, or other functionality is
       performed.  Proc::Daemon::Init just performs the main steps to ini-
       tialize a program as daemon.  Since other funtionality can vary
       depending on the nature of the program, Proc::Daemon leaves the imple-
       mentation of other desired functionality to the caller, or other mod-
       ule/library (like Sys::Syslog).

       There is no meaningful return value Proc::Daemon::Init.	If an error
       occurs in Init so it cannot perform the above steps, than it croaks
       with an error message.  One can prevent program termination by using
       eval.

OTHER FUNCTIONS
       Proc::Daemon also defines some other functions.	These functions can
       be imported into the callers name space if the function names are
       specified during the use declaration:

       Fork

       Fork is like the built-in fork, but will try to fork if at all possi-
       ble, retrying if necessary.  If not possible, Fork will croak.

       OpenMax

       OpenMax returns the maximum file descriptor number.  If undetermined,
       64 will be returned.

NOTES
       ·   Proc::Daemon::init is still available for backwards capatibilty.
	   However, it will not perform the double fork, and will return the
	   session ID.

AUTHOR
       Earl Hood, earl@earlhood.com

       http://www.earlhood.com/

CREDITS
       Implementation of Proc::Daemon derived from the following sources:

       ·   Advanced Programming in the UNIX Environment, by W. Richard
	   Stevens.  Addison-Wesley, Copyright 1992.

       ·   UNIX Network Progamming, Vol 1, by W. Richard Stevens.  Prentice-
	   Hall PTR, Copyright 1998.

DEPENDENCIES
       Carp, POSIX.

SEE ALSO
       POSIX, Sys::Syslog



perl v5.8.8			  2003-06-19			    Daemon(3)