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IO::Compress::Bzip2(3perl)       Perl Programmers Reference Guide      IO::Compress::Bzip2(3perl)

NAME
       IO::Compress::Bzip2 - Write bzip2 files/buffers

SYNOPSIS
           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

           my $status = bzip2 $input => $output [,OPTS]
               or die "bzip2 failed: $Bzip2Error\n";

           my $z = IO::Compress::Bzip2->new( $output [,OPTS] )
               or die "bzip2 failed: $Bzip2Error\n";

           $z->print($string);
           $z->printf($format, $string);
           $z->write($string);
           $z->syswrite($string [, $length, $offset]);
           $z->flush();
           $z->tell();
           $z->eof();
           $z->seek($position, $whence);
           $z->binmode();
           $z->fileno();
           $z->opened();
           $z->autoflush();
           $z->input_line_number();
           $z->newStream( [OPTS] );

           $z->close() ;

           $Bzip2Error ;

           # IO::File mode

           print $z $string;
           printf $z $format, $string;
           tell $z
           eof $z
           seek $z, $position, $whence
           binmode $z
           fileno $z
           close $z ;

DESCRIPTION
       This module provides a Perl interface that allows writing bzip2 compressed data to files
       or buffer.

       For reading bzip2 files/buffers, see the companion module IO::Uncompress::Bunzip2.

Functional Interface
       A top-level function, "bzip2", is provided to carry out "one-shot" compression between
       buffers and/or files. For finer control over the compression process, see the "OO
       Interface" section.

           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

           bzip2 $input_filename_or_reference => $output_filename_or_reference [,OPTS]
               or die "bzip2 failed: $Bzip2Error\n";

       The functional interface needs Perl5.005 or better.

   bzip2 $input_filename_or_reference => $output_filename_or_reference [, OPTS]
       "bzip2" expects at least two parameters, $input_filename_or_reference and
       $output_filename_or_reference and zero or more optional parameters (see "Optional
       Parameters")

       The $input_filename_or_reference parameter

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

       An Input FileGlob string
            If $input_filename_or_reference is a string that is delimited by the characters "<"
            and ">" "bzip2" 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
       compressed 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 compressed data will be
            written to it.

       A filehandle
            If the $output_filename_or_reference parameter is a filehandle, the compressed 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 compressed data will be
            stored in $$output_filename_or_reference.

       An Array Reference
            If $output_filename_or_reference is an array reference, the compressed 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 ">" "bzip2" 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 files/buffers and
       $output_filename_or_reference is a single file/buffer the input files/buffers will be
       stored in $output_filename_or_reference as a concatenated series of compressed data
       streams.

   Optional Parameters
       The optional parameters for the one-shot function "bzip2" are (for the most part)
       identical to those used with the OO interface defined in the "Constructor Options"
       section. The exceptions are listed below

       "AutoClose => 0|1"
            This option applies to any input or output data streams to "bzip2" 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 "bzip2" has completed.

            This parameter defaults to 0.

       "BinModeIn => 0|1"
            This option is now a no-op. All files will be read in binmode.

       "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 compressed data will be append to the end of the
                 output buffer. Otherwise the output buffer will be cleared before any compressed
                 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 compressed 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 compressed 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 compressed 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 compressed data. If the output is a filename, it will be opened for appending. If
            the output is a buffer, all compressed 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 compressed 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 compressed data is
            output.

            Defaults to 0.

   Examples
       Here are a few example that show the capabilities of the module.

       Streaming

       This very simple command line example demonstrates the streaming capabilities of the
       module.  The code reads data from STDIN, compresses it, and writes the compressed data to
       STDOUT.

           $ echo hello world | perl -MIO::Compress::Bzip2=bzip2 -e 'bzip2 \*STDIN => \*STDOUT' >output.bz2

       The special filename "-" can be used as a standin for both "\*STDIN" and "\*STDOUT", so
       the above can be rewritten as

           $ echo hello world | perl -MIO::Compress::Bzip2=bzip2 -e 'bzip2 "-" => "-"' >output.bz2

       Compressing a file from the filesystem

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

           use strict ;
           use warnings ;
           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

           my $input = "file1.txt";
           bzip2 $input => "$input.bz2"
               or die "bzip2 failed: $Bzip2Error\n";

       Reading from a Filehandle and writing to an in-memory buffer

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

           use strict ;
           use warnings ;
           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
           use IO::File ;

           my $input = IO::File->new( "<file1.txt" )
               or die "Cannot open 'file1.txt': $!\n" ;
           my $buffer ;
           bzip2 $input => \$buffer
               or die "bzip2 failed: $Bzip2Error\n";

       Compressing multiple files

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

           use strict ;
           use warnings ;
           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

           bzip2 '</my/home/*.txt>' => '<*.bz2>'
               or die "bzip2 failed: $Bzip2Error\n";

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

           use strict ;
           use warnings ;
           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

           for my $input ( glob "/my/home/*.txt" )
           {
               my $output = "$input.bz2" ;
               bzip2 $input => $output
                   or die "Error compressing '$input': $Bzip2Error\n";
           }

OO Interface
   Constructor
       The format of the constructor for "IO::Compress::Bzip2" is shown below

           my $z = IO::Compress::Bzip2->new( $output [,OPTS] )
               or die "IO::Compress::Bzip2 failed: $Bzip2Error\n";

       It returns an "IO::Compress::Bzip2" object on success and undef on failure.  The variable
       $Bzip2Error will contain an error message on failure.

       If you are running Perl 5.005 or better the object, $z, returned from IO::Compress::Bzip2
       can be used exactly like an IO::File filehandle.  This means that all normal output file
       operations can be carried out with $z.  For example, to write to a compressed file/buffer
       you can use either of these forms

           $z->print("hello world\n");
           print $z "hello world\n";

       The mandatory parameter $output is used to control the destination of the compressed data.
       This parameter can take one of these forms.

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

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

       A scalar reference
            If $output is a scalar reference, the compressed data will be stored in $$output.

       If the $output parameter is any other type, "IO::Compress::Bzip2"::new will return undef.

   Constructor Options
       "OPTS" is any combination of zero or more the following options:

       "AutoClose => 0|1"
            This option is only valid when the $output parameter is a filehandle. If specified,
            and the value is true, it will result in the $output being closed once either the
            "close" method is called or the "IO::Compress::Bzip2" object is destroyed.

            This parameter defaults to 0.

       "Append => 0|1"
            Opens $output in append mode.

            The behaviour of this option is dependent on the type of $output.

            o    A Buffer

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

            o    A Filename

                 If $output is a filename and "Append" is enabled, the file will be opened in
                 append mode. Otherwise the contents of the file, if any, will be truncated
                 before any compressed data is written to it.

            o    A Filehandle

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

            This parameter defaults to 0.

       "BlockSize100K => number"
            Specify the number of 100K blocks bzip2 uses during compression.

            Valid values are from 1 to 9, where 9 is best compression.

            The default is 1.

       "WorkFactor => number"
            Specifies how much effort bzip2 should take before resorting to a slower fallback
            compression algorithm.

            Valid values range from 0 to 250, where 0 means use the default value 30.

            The default is 0.

       "Strict => 0|1"
            This is a placeholder option.

   Examples
       TODO

Methods
   print
       Usage is

           $z->print($data)
           print $z $data

       Compresses and outputs the contents of the $data parameter. This has the same behaviour as
       the "print" built-in.

       Returns true if successful.

   printf
       Usage is

           $z->printf($format, $data)
           printf $z $format, $data

       Compresses and outputs the contents of the $data parameter.

       Returns true if successful.

   syswrite
       Usage is

           $z->syswrite $data
           $z->syswrite $data, $length
           $z->syswrite $data, $length, $offset

       Compresses and outputs the contents of the $data parameter.

       Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

   write
       Usage is

           $z->write $data
           $z->write $data, $length
           $z->write $data, $length, $offset

       Compresses and outputs the contents of the $data parameter.

       Returns the number of uncompressed bytes written, or "undef" if unsuccessful.

   flush
       Usage is

           $z->flush;

       Flushes any pending compressed data to the output file/buffer.

       TODO

       Returns true on success.

   tell
       Usage is

           $z->tell()
           tell $z

       Returns the uncompressed file offset.

   eof
       Usage is

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

       Returns true if the "close" method has been called.

   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 output file/buffer.  It is a fatal error to attempt to seek
       backward.

       Empty parts of the file/buffer will have NULL (0x00) bytes written to them.

       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)

       This method always returns "undef" when compressing.

   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 ;

       Flushes any pending compressed data and then closes the output file/buffer.

       For most versions of Perl this method will be automatically invoked if the
       IO::Compress::Bzip2 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::Compress::Bzip2 object was
       created, and the object is associated with a file, the underlying file will also be
       closed.

   newStream([OPTS])
       Usage is

           $z->newStream( [OPTS] )

       Closes the current compressed data stream and starts a new one.

       OPTS consists of any of the options that are available when creating the $z object.

       See the "Constructor Options" section for more details.

Importing
       No symbolic constants are required by IO::Compress::Bzip2 at present.

       :all Imports "bzip2" and $Bzip2Error.  Same as doing this

                use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;

EXAMPLES
   Apache::GZip Revisited
       See IO::Compress::FAQ

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

SUPPORT
       General feedback/questions/bug reports should be sent to
       <https://github.com/pmqs/IO-Compress/issues> (preferred) or
       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.

SEE ALSO
       Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate,
       IO::Uncompress::Inflate, IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
       IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma, IO::Compress::Xz,
       IO::Uncompress::UnXz, IO::Compress::Lzip, IO::Uncompress::UnLzip, IO::Compress::Lzop,
       IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Compress::Zstd,
       IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress

       IO::Compress::FAQ

       File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib

       The primary site for the bzip2 program is <https://sourceware.org/bzip2/>.

       See the module Compress::Bzip2

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

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2021 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 v5.34.0                                2023-11-23                 IO::Compress::Bzip2(3perl)

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