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IO::Uncompress::Bunzip2(3pm)




NAME

       IO::Uncompress::Bunzip2 - Read bzip2 files/buffers


SYNOPSIS

           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

           my $status = bunzip2 $input => $output [,OPTS]
               or die "bunzip2 failed: $Bunzip2Error\n";

           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
               or die "bunzip2 failed: $Bunzip2Error\n";

           $status = $z->read($buffer)
           $status = $z->read($buffer, $length)
           $status = $z->read($buffer, $length, $offset)
           $line = $z->getline()
           $char = $z->getc()
           $char = $z->ungetc()
           $char = $z->opened()

           $data = $z->trailingData()
           $status = $z->nextStream()
           $data = $z->getHeaderInfo()
           $z->tell()
           $z->seek($position, $whence)
           $z->binmode()
           $z->fileno()
           $z->eof()
           $z->close()

           $Bunzip2Error ;

           # IO::File mode

           <$z>
           read($z, $buffer);
           read($z, $buffer, $length);
           read($z, $buffer, $length, $offset);
           tell($z)
           seek($z, $position, $whence)
           binmode($z)
           fileno($z)
           eof($z)
           close($z)


DESCRIPTION

       This module provides a Perl interface that allows the reading of bzip2
       files/buffers.

       For writing bzip2 files/buffers, see the companion module
       IO::Compress::Bzip2.


Functional Interface

       A top-level function, "bunzip2", is provided to carry out "one-shot"
       uncompression between buffers and/or files. For finer control over the
       uncompression process, see the "OO Interface" section.

           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

           bunzip2 $input_filename_or_reference => $output_filename_or_reference [,OPTS]
               or die "bunzip2 failed: $Bunzip2Error\n";

       The functional interface needs Perl5.005 or better.

   bunzip2 $input_filename_or_reference => $output_filename_or_reference [,
       OPTS]
       "bunzip2" expects at least two parameters, $input_filename_or_reference
       and $output_filename_or_reference.

       The $input_filename_or_reference parameter

       The parameter, $input_filename_or_reference, is used to define the
       source of the compressed data.

       It can take one of the following forms:

       A filename
            If the <$input_filename_or_reference> parameter is a simple
            scalar, it is assumed to be a filename. This file will be opened
            for reading and the input data will be read from it.

       A filehandle
            If the $input_filename_or_reference parameter is a filehandle, the
            input data will be read from it.  The string '-' can be used as an
            alias for standard input.

       A scalar reference
            If $input_filename_or_reference is a scalar reference, the input
            data will be read from $$input_filename_or_reference.

       An array reference
            If $input_filename_or_reference is an array reference, each
            element in the array must be a filename.

            The input data will be read from each file in turn.

            The complete array will be walked to ensure that it only contains
            valid filenames before any data is uncompressed.

       An Input FileGlob string
            If $input_filename_or_reference is a string that is delimited by
            the characters "<" and ">" "bunzip2" will assume that it is an
            input fileglob string. The input is the list of files that match
            the fileglob.

            See File::GlobMapper for more details.

       If the $input_filename_or_reference parameter is any other type,
       "undef" will be returned.

       The $output_filename_or_reference parameter

       The parameter $output_filename_or_reference is used to control the
       destination of the uncompressed data. This parameter can take one of
       these forms.

       A filename
            If the $output_filename_or_reference parameter is a simple scalar,
            it is assumed to be a filename.  This file will be opened for
            writing and the uncompressed data will be written to it.

       A filehandle
            If the $output_filename_or_reference parameter is a filehandle,
            the uncompressed data will be written to it.  The string '-' can
            be used as an alias for standard output.

       A scalar reference
            If $output_filename_or_reference is a scalar reference, the
            uncompressed data will be stored in
            $$output_filename_or_reference.

       An Array Reference
            If $output_filename_or_reference is an array reference, the
            uncompressed data will be pushed onto the array.

       An Output FileGlob
            If $output_filename_or_reference is a string that is delimited by
            the characters "<" and ">" "bunzip2" will assume that it is an
            output fileglob string. The output is the list of files that match
            the fileglob.

            When $output_filename_or_reference is an fileglob string,
            $input_filename_or_reference must also be a fileglob string.
            Anything else is an error.

            See File::GlobMapper for more details.

       If the $output_filename_or_reference parameter is any other type,
       "undef" will be returned.

   Notes
       When $input_filename_or_reference maps to multiple compressed
       files/buffers and $output_filename_or_reference is a single
       file/buffer, after uncompression $output_filename_or_reference will
       contain a concatenation of all the uncompressed data from each of the
       input files/buffers.

   Optional Parameters
       Unless specified below, the optional parameters for "bunzip2", "OPTS",
       are the same as those used with the OO interface defined in the
       "Constructor Options" section below.

       "AutoClose => 0|1"
            This option applies to any input or output data streams to
            "bunzip2" that are filehandles.

            If "AutoClose" is specified, and the value is true, it will result
            in all input and/or output filehandles being closed once "bunzip2"
            has completed.

            This parameter defaults to 0.

       "BinModeOut => 0|1"
            When writing to a file or filehandle, set "binmode" before writing
            to the file.

            Defaults to 0.

       "Append => 0|1"
            The behaviour of this option is dependent on the type of output
            data stream.

            o    A Buffer

                 If "Append" is enabled, all uncompressed data will be append
                 to the end of the output buffer. Otherwise the output buffer
                 will be cleared before any uncompressed data is written to
                 it.

            o    A Filename

                 If "Append" is enabled, the file will be opened in append
                 mode. Otherwise the contents of the file, if any, will be
                 truncated before any uncompressed data is written to it.

            o    A Filehandle

                 If "Append" is enabled, the filehandle will be positioned to
                 the end of the file via a call to "seek" before any
                 uncompressed data is written to it.  Otherwise the file
                 pointer will not be moved.

            When "Append" is specified, and set to true, it will append all
            uncompressed data to the output data stream.

            So when the output is a filehandle it will carry out a seek to the
            eof before writing any uncompressed data. If the output is a
            filename, it will be opened for appending. If the output is a
            buffer, all uncompressed data will be appended to the existing
            buffer.

            Conversely when "Append" is not specified, or it is present and is
            set to false, it will operate as follows.

            When the output is a filename, it will truncate the contents of
            the file before writing any uncompressed data. If the output is a
            filehandle its position will not be changed. If the output is a
            buffer, it will be wiped before any uncompressed data is output.

            Defaults to 0.

       "MultiStream => 0|1"
            If the input file/buffer contains multiple compressed data
            streams, this option will uncompress the whole lot as a single
            data stream.

            Defaults to 0.

       "TrailingData => $scalar"
            Returns the data, if any, that is present immediately after the
            compressed data stream once uncompression is complete.

            This option can be used when there is useful information
            immediately following the compressed data stream, and you don't
            know the length of the compressed data stream.

            If the input is a buffer, "trailingData" will return everything
            from the end of the compressed data stream to the end of the
            buffer.

            If the input is a filehandle, "trailingData" will return the data
            that is left in the filehandle input buffer once the end of the
            compressed data stream has been reached. You can then use the
            filehandle to read the rest of the input file.

            Don't bother using "trailingData" if the input is a filename.

            If you know the length of the compressed data stream before you
            start uncompressing, you can avoid having to use "trailingData" by
            setting the "InputLength" option.

   Examples
       To read the contents of the file "file1.txt.bz2" and write the
       uncompressed data to the file "file1.txt".

           use strict ;
           use warnings ;
           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

           my $input = "file1.txt.bz2";
           my $output = "file1.txt";
           bunzip2 $input => $output
               or die "bunzip2 failed: $Bunzip2Error\n";

       To read from an existing Perl filehandle, $input, and write the
       uncompressed data to a buffer, $buffer.

           use strict ;
           use warnings ;
           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;
           use IO::File ;

           my $input = new IO::File "<file1.txt.bz2"
               or die "Cannot open 'file1.txt.bz2': $!\n" ;
           my $buffer ;
           bunzip2 $input => \$buffer
               or die "bunzip2 failed: $Bunzip2Error\n";

       To uncompress all files in the directory "/my/home" that match
       "*.txt.bz2" and store the compressed data in the same directory

           use strict ;
           use warnings ;
           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

           bunzip2 '</my/home/*.txt.bz2>' => '</my/home/#1.txt>'
               or die "bunzip2 failed: $Bunzip2Error\n";

       and if you want to compress each file one at a time, this will do the
       trick

           use strict ;
           use warnings ;
           use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;

           for my $input ( glob "/my/home/*.txt.bz2" )
           {
               my $output = $input;
               $output =~ s/.bz2// ;
               bunzip2 $input => $output
                   or die "Error compressing '$input': $Bunzip2Error\n";
           }


OO Interface

   Constructor
       The format of the constructor for IO::Uncompress::Bunzip2 is shown
       below

           my $z = new IO::Uncompress::Bunzip2 $input [OPTS]
               or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";

       Returns an "IO::Uncompress::Bunzip2" object on success and undef on
       failure.  The variable $Bunzip2Error will contain an error message on
       failure.

       If you are running Perl 5.005 or better the object, $z, returned from
       IO::Uncompress::Bunzip2 can be used exactly like an IO::File
       filehandle.  This means that all normal input file operations can be
       carried out with $z.  For example, to read a line from a compressed
       file/buffer you can use either of these forms

           $line = $z->getline();
           $line = <$z>;

       The mandatory parameter $input is used to determine the source of the
       compressed data. This parameter can take one of three forms.

       A filename
            If the $input parameter is a scalar, it is assumed to be a
            filename. This file will be opened for reading and the compressed
            data will be read from it.

       A filehandle
            If the $input parameter is a filehandle, the compressed data will
            be read from it.  The string '-' can be used as an alias for
            standard input.

       A scalar reference
            If $input is a scalar reference, the compressed data will be read
            from $$input.

   Constructor Options
       The option names defined below are case insensitive and can be
       optionally prefixed by a '-'.  So all of the following are valid

           -AutoClose
           -autoclose
           AUTOCLOSE
           autoclose

       OPTS is a combination of the following options:

       "AutoClose => 0|1"
            This option is only valid when the $input parameter is a
            filehandle. If specified, and the value is true, it will result in
            the file being closed once either the "close" method is called or
            the IO::Uncompress::Bunzip2 object is destroyed.

            This parameter defaults to 0.

       "MultiStream => 0|1"
            Allows multiple concatenated compressed streams to be treated as a
            single compressed stream. Decompression will stop once either the
            end of the file/buffer is reached, an error is encountered
            (premature eof, corrupt compressed data) or the end of a stream is
            not immediately followed by the start of another stream.

            This parameter defaults to 0.

       "Prime => $string"
            This option will uncompress the contents of $string before
            processing the input file/buffer.

            This option can be useful when the compressed data is embedded in
            another file/data structure and it is not possible to work out
            where the compressed data begins without having to read the first
            few bytes. If this is the case, the uncompression can be primed
            with these bytes using this option.

       "Transparent => 0|1"
            If this option is set and the input file/buffer is not compressed
            data, the module will allow reading of it anyway.

            In addition, if the input file/buffer does contain compressed data
            and there is non-compressed data immediately following it, setting
            this option will make this module treat the whole file/buffer as a
            single data stream.

            This option defaults to 1.

       "BlockSize => $num"
            When reading the compressed input data, IO::Uncompress::Bunzip2
            will read it in blocks of $num bytes.

            This option defaults to 4096.

       "InputLength => $size"
            When present this option will limit the number of compressed bytes
            read from the input file/buffer to $size. This option can be used
            in the situation where there is useful data directly after the
            compressed data stream and you know beforehand the exact length of
            the compressed data stream.

            This option is mostly used when reading from a filehandle, in
            which case the file pointer will be left pointing to the first
            byte directly after the compressed data stream.

            This option defaults to off.

       "Append => 0|1"
            This option controls what the "read" method does with uncompressed
            data.

            If set to 1, all uncompressed data will be appended to the output
            parameter of the "read" method.

            If set to 0, the contents of the output parameter of the "read"
            method will be overwritten by the uncompressed data.

            Defaults to 0.

       "Strict => 0|1"
            This option is a no-op.

       "Small => 0|1"
            When non-zero this options will make bzip2 use a decompression
            algorithm that uses less memory at the expense of increasing the
            amount of time taken for decompression.

            Default is 0.

   Examples
       TODO


Methods

   read
       Usage is

           $status = $z->read($buffer)

       Reads a block of compressed data (the size of the compressed block is
       determined by the "Buffer" option in the constructor), uncompresses it
       and writes any uncompressed data into $buffer. If the "Append"
       parameter is set in the constructor, the uncompressed data will be
       appended to the $buffer parameter. Otherwise $buffer will be
       overwritten.

       Returns the number of uncompressed bytes written to $buffer, zero if
       eof or a negative number on error.

   read
       Usage is

           $status = $z->read($buffer, $length)
           $status = $z->read($buffer, $length, $offset)

           $status = read($z, $buffer, $length)
           $status = read($z, $buffer, $length, $offset)

       Attempt to read $length bytes of uncompressed data into $buffer.

       The main difference between this form of the "read" method and the
       previous one, is that this one will attempt to return exactly $length
       bytes. The only circumstances that this function will not is if end-of-
       file or an IO error is encountered.

       Returns the number of uncompressed bytes written to $buffer, zero if
       eof or a negative number on error.

   getline
       Usage is

           $line = $z->getline()
           $line = <$z>

       Reads a single line.

       This method fully supports the use of the variable $/ (or
       $INPUT_RECORD_SEPARATOR or $RS when "English" is in use) to determine
       what constitutes an end of line. Paragraph mode, record mode and file
       slurp mode are all supported.

   getc
       Usage is

           $char = $z->getc()

       Read a single character.

   ungetc
       Usage is

           $char = $z->ungetc($string)

   getHeaderInfo
       Usage is

           $hdr  = $z->getHeaderInfo();
           @hdrs = $z->getHeaderInfo();

       This method returns either a hash reference (in scalar context) or a
       list or hash references (in array context) that contains information
       about each of the header fields in the compressed data stream(s).

   tell
       Usage is

           $z->tell()
           tell $z

       Returns the uncompressed file offset.

   eof
       Usage is

           $z->eof();
           eof($z);

       Returns true if the end of the compressed input stream has been
       reached.

   seek
           $z->seek($position, $whence);
           seek($z, $position, $whence);

       Provides a sub-set of the "seek" functionality, with the restriction
       that it is only legal to seek forward in the input file/buffer.  It is
       a fatal error to attempt to seek backward.

       Note that the implementation of "seek" in this module does not provide
       true random access to a compressed file/buffer. It  works by
       uncompressing data from the current offset in the file/buffer until it
       reaches the uncompressed offset specified in the parameters to "seek".
       For very small files this may be acceptable behaviour. For large files
       it may cause an unacceptable delay.

       The $whence parameter takes one the usual values, namely SEEK_SET,
       SEEK_CUR or SEEK_END.

       Returns 1 on success, 0 on failure.

   binmode
       Usage is

           $z->binmode
           binmode $z ;

       This is a noop provided for completeness.

   opened
           $z->opened()

       Returns true if the object currently refers to a opened file/buffer.

   autoflush
           my $prev = $z->autoflush()
           my $prev = $z->autoflush(EXPR)

       If the $z object is associated with a file or a filehandle, this method
       returns the current autoflush setting for the underlying filehandle. If
       "EXPR" is present, and is non-zero, it will enable flushing after every
       write/print operation.

       If $z is associated with a buffer, this method has no effect and always
       returns "undef".

       Note that the special variable $| cannot be used to set or retrieve the
       autoflush setting.

   input_line_number
           $z->input_line_number()
           $z->input_line_number(EXPR)

       Returns the current uncompressed line number. If "EXPR" is present it
       has the effect of setting the line number. Note that setting the line
       number does not change the current position within the file/buffer
       being read.

       The contents of $/ are used to determine what constitutes a line
       terminator.

   fileno
           $z->fileno()
           fileno($z)

       If the $z object is associated with a file or a filehandle, "fileno"
       will return the underlying file descriptor. Once the "close" method is
       called "fileno" will return "undef".

       If the $z object is associated with a buffer, this method will return
       "undef".

   close
           $z->close() ;
           close $z ;

       Closes the output file/buffer.

       For most versions of Perl this method will be automatically invoked if
       the IO::Uncompress::Bunzip2 object is destroyed (either explicitly or
       by the variable with the reference to the object going out of scope).
       The exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In
       these cases, the "close" method will be called automatically, but not
       until global destruction of all live objects when the program is
       terminating.

       Therefore, if you want your scripts to be able to run on all versions
       of Perl, you should call "close" explicitly and not rely on automatic
       closing.

       Returns true on success, otherwise 0.

       If the "AutoClose" option has been enabled when the
       IO::Uncompress::Bunzip2 object was created, and the object is
       associated with a file, the underlying file will also be closed.

   nextStream
       Usage is

           my $status = $z->nextStream();

       Skips to the next compressed data stream in the input file/buffer. If a
       new compressed data stream is found, the eof marker will be cleared and
       $.  will be reset to 0.

       Returns 1 if a new stream was found, 0 if none was found, and -1 if an
       error was encountered.

   trailingData
       Usage is

           my $data = $z->trailingData();

       Returns the data, if any, that is present immediately after the
       compressed data stream once uncompression is complete. It only makes
       sense to call this method once the end of the compressed data stream
       has been encountered.

       This option can be used when there is useful information immediately
       following the compressed data stream, and you don't know the length of
       the compressed data stream.

       If the input is a buffer, "trailingData" will return everything from
       the end of the compressed data stream to the end of the buffer.

       If the input is a filehandle, "trailingData" will return the data that
       is left in the filehandle input buffer once the end of the compressed
       data stream has been reached. You can then use the filehandle to read
       the rest of the input file.

       Don't bother using "trailingData" if the input is a filename.

       If you know the length of the compressed data stream before you start
       uncompressing, you can avoid having to use "trailingData" by setting
       the "InputLength" option in the constructor.


Importing

       No symbolic constants are required by this IO::Uncompress::Bunzip2 at
       present.

       :all Imports "bunzip2" and $Bunzip2Error.  Same as doing this

                use IO::Uncompress::Bunzip2 qw(bunzip2 $Bunzip2Error) ;


EXAMPLES

   Working with Net::FTP
       See IO::Compress::FAQ


SEE ALSO

       Compress::Zlib(3), IO::Compress::Gzip(3), IO::Uncompress::Gunzip(3),
       IO::Compress::Deflate(3), IO::Uncompress::Inflate(3),
       IO::Compress::RawDeflate(3), IO::Uncompress::RawInflate(3),
       IO::Compress::Bzip2(3), IO::Compress::Lzma(3),
       IO::Uncompress::UnLzma(3), IO::Compress::Xz(3),
       IO::Uncompress::UnXz(3), IO::Compress::Lzop(3),
       IO::Uncompress::UnLzop(3), IO::Compress::Lzf(3),
       IO::Uncompress::UnLzf(3), IO::Uncompress::AnyInflate(3),
       IO::Uncompress::AnyUncompress(3)

       IO::Compress::FAQ(3)

       File::GlobMapper(3), Archive::Zip(3), Archive::Tar(3), IO::Zlib(3)

       The primary site for the bzip2 program is http://www.bzip.org.

       See the module Compress::Bzip2(3)


AUTHOR

       This module was written by Paul Marquess, "pmqs@cpan.org".


MODIFICATION HISTORY

       See the Changes file.


COPYRIGHT AND LICENSE

       Copyright (c) 2005-2017 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.



perl v5.26.1                      2017-07-18      IO::Uncompress::Bunzip2(3pm)

perl 5.26.1 - Generated Sun Nov 5 15:08:59 CST 2017
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