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IO::AtomicFile(3)	       User Contributed Perl Documentation		IO::AtomicFile(3)

NAME
       IO::AtomicFile - write a file which is updated atomically

SYNOPSIS
	   use IO::AtomicFile;

	   ### Write a temp file, and have it install itself when closed:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!\n";
	   $FH->close || die "couldn't install atomic file: $!";

	   ### Write a temp file, but delete it before it gets installed:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!\n";
	   $FH->delete;

	   ### Write a temp file, but neither install it nor delete it:
	   my $FH = IO::AtomicFile->open("bar.dat", "w");
	   print $FH "Hello!\n";
	   $FH->detach;

DESCRIPTION
       This module is intended for people who need to update files reliably in the face of
       unexpected program termination.

       For example, you generally don't want to be halfway in the middle of writing /etc/passwd
       and have your program terminate!  Even the act of writing a single scalar to a filehandle
       is not atomic.

       But this module gives you true atomic updates, via rename().  When you open a file
       /foo/bar.dat via this module, you are actually opening a temporary file /foo/bar.dat..TMP,
       and writing your output there.	The act of closing this file (either explicitly via
       close(), or implicitly via the destruction of the object) will cause rename() to be
       called... therefore, from the point of view of the outside world, the file's contents are
       updated in a single time quantum.

       To ensure that problems do not go undetected, the "close" method done by the destructor
       will raise a fatal exception if the rename() fails.  The explicit close() just returns
       undef.

       You can also decide at any point to trash the file you've been building.

AUTHOR
   Primary Maintainer
       David F. Skoll (dfs@roaringpenguin.com).

   Original Author
       Eryq (eryq@zeegee.com).	President, ZeeGee Software Inc (http://www.zeegee.com).

REVISION
       $Revision: 1.2 $

perl v5.16.3				    2005-02-10				IO::AtomicFile(3)
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