Skip site navigation (1)Skip section navigation (2)

FreeBSD Manual Pages

  
 
  

home | help
IO::Compress::Bzip2(3) Perl Programmers	Reference Guide	IO::Compress::Bzip2(3)

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@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 v5.35.11			  2022-03-27		IO::Compress::Bzip2(3)

NAME | SYNOPSIS | DESCRIPTION | Functional Interface | OO Interface | Methods | Importing | EXAMPLES | SUPPORT | SEE ALSO | AUTHOR | MODIFICATION HISTORY | COPYRIGHT AND LICENSE

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=IO::Compress::Bzip2&sektion=3&manpath=FreeBSD+13.1-RELEASE+and+Ports>

home | help