phpMan > man > 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
    Dianne Skoll (dfs AT roaringpenguin.com).

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

REVISION
    $Revision: 1.2 $