Fix use of a variable before it is initialised, introduced by change

[p5sagit/p5-mst-13.2.git] / ext / Compress / Zlib / pod / FAQ.pod

=head1 NAME

Compress::Zlib::FAQ -- Frequently Asked Questions about Compress::Zlib

=head1 DESCRIPTION

Common questions answered.

=head2 Compatibility with Unix compress/uncompress.

Although C<Compress::Zlib> has a pair of functions called C<compress> and
C<uncompress>, they are I<not> related to the Unix programs of the same
name. The C<Compress::Zlib> module is not compatible with Unix
C<compress>.

If you have the C<uncompress> program available, you can use this to read
compressed files

    open F, "uncompress -c $filename |";
    while (<F>)
    {
        ...

Alternatively, if you have the C<gunzip> program available, you can use
this to read compressed files

    open F, "gunzip -c $filename |";
    while (<F>)
    {
        ...

and this to write compress files, if you have the C<compress> program
available

    open F, "| compress -c $filename ";
    print F "data";
    ...
    close F ;

=head2 Accessing .tar.Z files

The C<Archive::Tar> module can optionally use C<Compress::Zlib> (via the
C<IO::Zlib> module) to access tar files that have been compressed with
C<gzip>. Unfortunately tar files compressed with the Unix C<compress>
utility cannot be read by C<Compress::Zlib> and so cannot be directly
accessed by C<Archive::Tar>.

If the C<uncompress> or C<gunzip> programs are available, you can use one
of these workarounds to read C<.tar.Z> files from C<Archive::Tar>

Firstly with C<uncompress>

    use strict;
    use warnings;
    use Archive::Tar;

    open F, "uncompress -c $filename |";
    my $tar = Archive::Tar->new(*F);
    ...

and this with C<gunzip>

    use strict;
    use warnings;
    use Archive::Tar;

    open F, "gunzip -c $filename |";
    my $tar = Archive::Tar->new(*F);
    ...

Similarly, if the C<compress> program is available, you can use this to
write a C<.tar.Z> file

    use strict;
    use warnings;
    use Archive::Tar;
    use IO::File;

    my $fh = new IO::File "| compress -c >$filename";
    my $tar = Archive::Tar->new();
    ...
    $tar->write($fh);
    $fh->close ;

=head2 Accessing Zip Files

This module does not support reading/writing zip files.

Support for reading/writing zip files is included with the
C<IO::Compress::Zip> and C<IO::Uncompress::Unzip> modules.

The primary focus of the C<IO::Compress::Zip> and C<IO::Uncompress::Unzip>
modules is to provide an C<IO::File> compatible streaming read/write
interface to zip files/buffers. They are not fully flegged archivers. If
you are looking for an archiver check out the C<Archive::Zip> module. You
can find it on CPAN at 

    http://www.cpan.org/modules/by-module/Archive/Archive-Zip-*.tar.gz    

=head1 SEE ALSO

L<Compress::Zlib>, L<IO::Compress::Gzip>, L<IO::Uncompress::Gunzip>, L<IO::Compress::Deflate>, L<IO::Uncompress::Inflate>, L<IO::Compress::RawDeflate>, L<IO::Uncompress::RawInflate>, L<IO::Compress::Bzip2>, L<IO::Uncompress::Bunzip2>, L<IO::Compress::Lzop>, L<IO::Uncompress::UnLzop>, L<IO::Compress::Lzf>, L<IO::Uncompress::UnLzf>, L<IO::Uncompress::AnyInflate>, L<IO::Uncompress::AnyUncompress>

L<Compress::Zlib::FAQ|Compress::Zlib::FAQ>

L<File::GlobMapper|File::GlobMapper>, L<Archive::Zip|Archive::Zip>,
L<Archive::Tar|Archive::Tar>,
L<IO::Zlib|IO::Zlib>

=head1 AUTHOR

This module was written by Paul Marquess, F<pmqs@cpan.org>. 

=head1 MODIFICATION HISTORY

See the Changes file.

=head1 COPYRIGHT AND LICENSE

Copyright (c) 2005-2008 Paul Marquess. All rights reserved.

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