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

IO::Compress::Bzip2(3p) Perl Programmers Reference Guide #

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

NNAAMMEE #

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

SSYYNNOOPPSSIISS #

     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 ;

DDEESSCCRRIIPPTTIIOONN #

 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.

FFuunnccttiioonnaall IInntteerrffaaccee 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.

bbzziipp22 $$iinnppuutt__ffiilleennaammee__oorr__rreeffeerreennccee ==>> $$oouuttppuutt__ffiilleennaammee__oorr__rreeffeerreennccee [[,,

OOPPTTSS]] #

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

 _T_h_e _$_i_n_p_u_t___f_i_l_e_n_a_m_e___o_r___r_e_f_e_r_e_n_c_e _p_a_r_a_m_e_t_e_r

 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 _i_n_p_u_t
      _f_i_l_e_g_l_o_b _s_t_r_i_n_g. 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.

 _T_h_e _$_o_u_t_p_u_t___f_i_l_e_n_a_m_e___o_r___r_e_f_e_r_e_n_c_e _p_a_r_a_m_e_t_e_r

 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 _o_u_t_p_u_t
      _f_i_l_e_g_l_o_b _s_t_r_i_n_g. 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.

NNootteess 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.

OOppttiioonnaall PPaarraammeetteerrss 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.

      •    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.

      •    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.

      •    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 _a_p_p_e_n_d 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.

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

 _S_t_r_e_a_m_i_n_g

 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

 _C_o_m_p_r_e_s_s_i_n_g _a _f_i_l_e _f_r_o_m _t_h_e _f_i_l_e_s_y_s_t_e_m

 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";

 _R_e_a_d_i_n_g _f_r_o_m _a _F_i_l_e_h_a_n_d_l_e _a_n_d _w_r_i_t_i_n_g _t_o _a_n _i_n_-_m_e_m_o_r_y _b_u_f_f_e_r

 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";

 _C_o_m_p_r_e_s_s_i_n_g _m_u_l_t_i_p_l_e _f_i_l_e_s

 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";
     }

OOOO IInntteerrffaaccee CCoonnssttrruuccttoorr 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.

CCoonnssttrruuccttoorr OOppttiioonnss “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.

      •    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.

      •    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.

      •    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.

EExxaammpplleess

TODO #

MMeetthhooddss pprriinntt 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.

pprriinnttff Usage is

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

 Compresses and outputs the contents of the $data parameter.

 Returns true if successful.

ssyysswwrriittee 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.

wwrriittee 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.

fflluusshh Usage is

     $z->flush;

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

TODO #

 Returns true on success.

tteellll Usage is

     $z->tell()
     tell $z

 Returns the uncompressed file offset.

eeooff Usage is

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

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

sseeeekk $z->seek($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.

bbiinnmmooddee Usage is

     $z->binmode
     binmode $z ;

 This is a noop provided for completeness.

ooppeenneedd $z->opened()

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

aauuttoofflluusshh 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".

 NNoottee that the special variable $| ccaannnnoott be used to set or retrieve the
 autoflush setting.

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

 This method always returns "undef" when compressing.

ffiilleennoo $z->fileno() fileno($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".

cclloossee $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.

nneewwSSttrreeaamm(([[OOPPTTSS]])) 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.

IImmppoorrttiinngg 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) ;

EEXXAAMMPPLLEESS #

AAppaacchhee::::GGZZiipp RReevviissiitteedd See IO::Compress::FAQ

WWoorrkkiinngg wwiitthh NNeett::::FFTTPP See IO::Compress::FAQ

SSUUPPPPOORRTT #

 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>.

SSEEEE AALLSSOO #

 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

AAUUTTHHOORR #

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

MMOODDIIFFIICCAATTIIOONN HHIISSTTOORRYY #

 See the Changes file.

CCOOPPYYRRIIGGHHTT AANNDD LLIICCEENNSSEE #

 Copyright (c) 2005-2022 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 v5.36.3 2023-02-15 IO::Compress::Bzip2(3p)