File::Update - update/modify/mutate a file only on change in contents.


version 0.0.2


    use Path::Tiny qw/ path /;
    use File::Update qw/ write_on_change /;

    my $text = "Updated on " . strftime("%Y-%m-%d", time) . "\n";

    write_on_change(path("dated-file.txt"), \$text);


version 0.0.2


write_on_change($path, \"new contents")

Accepts a Path::Tiny like object and a reference to a string that contains the new contents. Writes the new content only if it is different from the existing one in the file.

modify_on_change($path, sub { my $t = shift; return $$t =~ s/old/new/g;})

Accepts a subroutine reference that accepts the reference to the existing content, can mutate it and if it returns a true value, the new text is written to the file.

write_on_change_no_utf8($path, \"new contents")

Like write_on_change() but while using Path::Tiny's non-utf8 methods.


Shlomi Fish <>


This software is Copyright (c) 2018 by Shlomi Fish.

This is free software, licensed under:

  The MIT (X11) License


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.



You can find documentation for this module with the perldoc command.

  perldoc File::Update


The following websites have more information about this module, and may be of help to you. As always, in addition to those websites please use your favorite search engine to discover more resources.

Bugs / Feature Requests

Please report any bugs or feature requests by email to bug-file-update at, or through the web interface at You will be automatically notified of any progress on the request by the system.

Source Code

The code is open to the world, and available for you to hack on. Please feel free to browse it and play with it, or whatever. If you want to contribute patches, please send me a diff or prod me to pull from your repository :)

  git clone