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



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 v5.10.0                      2008-06-29               IO::AtomicFile(3pm)