NAME

Acme::CPANModules::ReadingFilesBackward - Reading files backward (in reverse)

VERSION

This document describes version 0.002 of Acme::CPANModules::ReadingFilesBackward (from Perl distribution Acme-CPANModules-ReadingFilesBackward), released on 2020-03-01.

DESCRIPTION

Reading files backward (in reverse).

Probably the fastest way, if you are on a Unix system, is to use the tac command, which can read a file line by line in reverse order, or paragraph by paragraph, or character by character, or word by word, or by a custom separator string or regular expression. Example for using it from Perl:

open my $fh, "tac /etc/passwd |";
print while <$fh>;

Another convenient way is to use the Perl I/O layer PerlIO::reverse. It only does line-by-line reversing, but you can use the regular Perl API. You don't even have to use the module explicitly (but of course you have to get it installed first):

open my $fh, "<:reverse", "/etc/passwd";
print while <$fh>;

If your file is small (fits in your system's memory), you can also slurp the file contents first into an array (either line by line, or paragraph by paragraph, or what have you) and then simply reverse the array:

open my $fh, "<", "/etc/passwd";
my @lines = <$fh>;
print for reverse @lines;

If the above solutions do not fit your needs, there are also these modules which can help: File::ReadBackward, File::Bidirectional. File::ReadBackward is slightly faster than File::Bidirectional, but File::Bidirectional can read forward as well as backward. I now simply prefer PerlIO::reverse because I don't have to use a custom API for reading files.

INCLUDED MODULES

• PerlIO::reverse

• File::ReadBackward

• File::Bidirectional

FAQ

What are ways to use this module?

Aside from reading it, you can install all the listed modules using cpanmodules:

% cpanmodules ls-entries ReadingFilesBackward | cpanm -n

or Acme::CM::Get:

% perl -MAcme::CM::Get=ReadingFilesBackward -E'say $_->{module} for @{ $LIST->{entries} }' | cpanm -n

This module also helps lcpan produce a more meaningful result for lcpan related-mods when it comes to finding related modules for the modules listed in this Acme::CPANModules module.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Acme-CPANModules-ReadingFilesBackward.

SOURCE

Source repository is at https://github.com/perlancar/perl-Acme-CPANModules-ReadingFilesBackward.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Acme-CPANModules-ReadingFilesBackward

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.

SEE ALSO

Acme::CPANModules::PickingRandomLinesFromFile

Acme::CPANModules - about the Acme::CPANModules namespace

cpanmodules - CLI tool to let you browse/view the lists

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2020 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

cpanm Acme::CPANModules::ReadingFilesBackward

perl -MCPAN -e shell
install Acme::CPANModules::ReadingFilesBackward