NAME
File::Symlink::Atomic - an atomic drop-in replacement for CORE::symlink
VERSION
version 0.002
SYNOPSIS
use File::Symlink::Atomic; # imports replacement symlink
symlink "target", "name1"; # easy peasy
symlink "bullseye", "name1"; # now atomic
DESCRIPTION
Actually creating a symlink is not problematic, but making an existing
one point at a new target may not be atomic on your system. For example,
on Linux, the system does "unlink" and then "symlink". In between, no
symlink exists. If something goes wrong, you're left with nothing.
In your shell, you probably want to do something like:
mkdir old-target new target # Create your targets
ln -s old-target link # Create your initial symlink
# ln -sf new-target link # NOT atomic!
ln -s new-target link-tmp && mv -Tf link-tmp link
Moving the symlink to the new name makes it atomic, because under the
hood, the "mv" command does "rename", which is guaranteed to be atomic
by POSIX
File::Symlink::Atomic attempts to do the same thing in Perl what the
command shown above does for your shell.
FUNCTIONS
symlink OLDFILE,NEWFILE
Creates a new filename symbolically linked to the old filename. Returns
1 for success, 0 otherwise. This drop-in replacement for "CORE::symlink"
creates a symlink with a temporary name, then renames it to the name you
requested - this ensures that if a symlink by the requested name already
existed, then its target is updated atomically.
CAVEATS
This module is not guaranteed to be portable. I have no idea what this
will do on any platform other than Linux. Feel free to run the test
suite to find out!
AVAILABILITY
The project homepage is
The latest version of this module is available from the Comprehensive
CPAN site near you, or see
SOURCE
The development version is on github at
BUGS AND LIMITATIONS
You can make new bug reports, and view existing ones, through the web
AUTHOR
Mike Doherty <doherty@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 by Mike Doherty.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.