Dpkg::Compression::FileHandle man page on ElementaryOS

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Dpkg::Compression::FileHandle(3) libdpkg-perl Dpkg::Compression::FileHandle(3)

       Dpkg::Compression::FileHandle - object dealing transparently with file

	   use Dpkg::Compression::FileHandle;

	   $fh = Dpkg::Compression::FileHandle->new(filename => 'sample.gz');
	   print $fh "Something\n";
	   close $fh;

	   $fh = Dpkg::Compression::FileHandle->new();
	   open($fh, '>', 'sample.bz2');
	   print $fh "Something\n";
	   close $fh;

	   $fh = Dpkg::Compression::FileHandle->new();
	   $fh->open('sample.xz', 'w');

	   $fh = Dpkg::Compression::FileHandle->new(filename => 'sample.gz');
	   my @lines = <$fh>;
	   close $fh;

	   $fh = Dpkg::Compression::FileHandle->new();
	   open($fh, '<', 'sample.bz2');
	   my @lines = <$fh>;
	   close $fh;

	   $fh = Dpkg::Compression::FileHandle->new();
	   $fh->open('sample.xz', 'r');
	   my @lines = $fh->getlines();

       Dpkg::Compression::FileHandle is an object that can be used like any
       filehandle and that deals transparently with compressed files. By
       default, the compression scheme is guessed from the filename but you
       can override this behaviour with the method "set_compression".

       If you don't open the file explicitly, it will be auto-opened on the
       first read or write operation based on the filename set at creation
       time (or later with the "set_filename" method).

       Once a file has been opened, the filehandle must be closed before being
       able to open another file.

       The standard functions acting on filehandles should accept a
       Dpkg::Compression::FileHandle object transparently including "open"
       (only when using the variant with 3 parameters), "close", "binmode",
       "eof", "fileno", "getc", "print", "printf", "read", "sysread", "say",
       "write", "syswrite", "seek", "sysseek", "tell".

       Note however that "seek" and "sysseek" will only work on uncompressed
       files as compressed files are really pipes to the compressor programs
       and you can't seek on a pipe.

FileHandle METHODS
       The object inherits from FileHandle so all methods that work on this
       object should work for Dpkg::Compression::FileHandle too. There may be
       exceptions though.

       my $fh = Dpkg::Compression::FileHandle->new(%opts)
	   Creates a new filehandle supporting on-the-fly
	   compression/decompression.  Supported options are "filename",
	   "compression", "compression_level" (see respective set_* functions)
	   and "add_comp_ext". If "add_comp_ext" evaluates to true, then the
	   extension corresponding to the selected compression scheme is
	   automatically added to the recorded filename. It's obviously
	   incompatible with automatic detection of the compression method.

	   Ensure the file is opened in the requested mode ("r" for read and
	   "w" for write). Opens the file with the recorded filename if
	   needed. If the file is already open but not in the requested mode,
	   then it errors out.

	   Defines the compression method used. $comp should one of the
	   methods supported by Dpkg::Compression or "none" or "auto". "none"
	   indicates that the file is uncompressed and "auto" indicates that
	   the method must be guessed based on the filename extension used.

	   Indicate the desired compression level. It should be a value
	   accepted by the function "compression_is_valid_level" of

       $fh->set_filename($name, [$add_comp_ext])
	   Use $name as filename when the file must be opened/created. If
	   $add_comp_ext is passed, it indicates whether the default extension
	   of the compression method must be automatically added to the
	   filename (or not).

       my $file = $fh->get_filename()
	   Returns the filename that would be used when the filehandle must be
	   opened (both in read and write mode). This function errors out if
	   "add_comp_ext" is enabled while the compression method is set to
	   "auto". The returned filename includes the extension of the
	   compression method if "add_comp_ext" is enabled.

       $ret = $fh->use_compression()
	   Returns "0" if no compression is used and the compression method
	   used otherwise. If the compression is set to "auto", the value
	   returned depends on the extension of the filename obtained with the
	   get_filename method.

       my $real_fh = $fh->get_filehandle()
	   Returns the real underlying filehandle. Useful if you want to pass
	   it along in a derived object.

       If you want to create an object that inherits from
       Dpkg::Compression::FileHandle you must be aware that the object is a
       reference to a GLOB that is returned by Symbol::gensym() and as such
       it's not a HASH.

       You can store internal data in a hash but you have to use
       "*$self-"{...}> to access the associated hash like in the example

	   sub set_option {
	       my ($self, $value) = @_;
	       *$self->{option} = $value;

       Raphaƫl Hertzog <hertzog@debian.org>

1.17.5				  2013-12-10  Dpkg::Compression::FileHandle(3)

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