1IO::Compress::Bzip2(3)User Contributed Perl DocumentationIO::Compress::Bzip2(3)
2
3
4

NAME

6       IO::Compress::Bzip2 - Write bzip2 files/buffers
7

SYNOPSIS

9           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
10
11           my $status = bzip2 $input => $output [,OPTS]
12               or die "bzip2 failed: $Bzip2Error\n";
13
14           my $z = IO::Compress::Bzip2->new( $output [,OPTS] )
15               or die "bzip2 failed: $Bzip2Error\n";
16
17           $z->print($string);
18           $z->printf($format, $string);
19           $z->write($string);
20           $z->syswrite($string [, $length, $offset]);
21           $z->flush();
22           $z->tell();
23           $z->eof();
24           $z->seek($position, $whence);
25           $z->binmode();
26           $z->fileno();
27           $z->opened();
28           $z->autoflush();
29           $z->input_line_number();
30           $z->newStream( [OPTS] );
31
32           $z->close() ;
33
34           $Bzip2Error ;
35
36           # IO::File mode
37
38           print $z $string;
39           printf $z $format, $string;
40           tell $z
41           eof $z
42           seek $z, $position, $whence
43           binmode $z
44           fileno $z
45           close $z ;
46

DESCRIPTION

48       This module provides a Perl interface that allows writing bzip2
49       compressed data to files or buffer.
50
51       For reading bzip2 files/buffers, see the companion module
52       IO::Uncompress::Bunzip2.
53

Functional Interface

55       A top-level function, "bzip2", is provided to carry out "one-shot"
56       compression between buffers and/or files. For finer control over the
57       compression process, see the "OO Interface" section.
58
59           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
60
61           bzip2 $input_filename_or_reference => $output_filename_or_reference [,OPTS]
62               or die "bzip2 failed: $Bzip2Error\n";
63
64       The functional interface needs Perl5.005 or better.
65
66   bzip2 $input_filename_or_reference => $output_filename_or_reference [,
67       OPTS]
68       "bzip2" expects at least two parameters, $input_filename_or_reference
69       and $output_filename_or_reference and zero or more optional parameters
70       (see "Optional Parameters")
71
72       The $input_filename_or_reference parameter
73
74       The parameter, $input_filename_or_reference, is used to define the
75       source of the uncompressed data.
76
77       It can take one of the following forms:
78
79       A filename
80            If the $input_filename_or_reference parameter is a simple scalar,
81            it is assumed to be a filename. This file will be opened for
82            reading and the input data will be read from it.
83
84       A filehandle
85            If the $input_filename_or_reference parameter is a filehandle, the
86            input data will be read from it.  The string '-' can be used as an
87            alias for standard input.
88
89       A scalar reference
90            If $input_filename_or_reference is a scalar reference, the input
91            data will be read from $$input_filename_or_reference.
92
93       An array reference
94            If $input_filename_or_reference is an array reference, each
95            element in the array must be a filename.
96
97            The input data will be read from each file in turn.
98
99            The complete array will be walked to ensure that it only contains
100            valid filenames before any data is compressed.
101
102       An Input FileGlob string
103            If $input_filename_or_reference is a string that is delimited by
104            the characters "<" and ">" "bzip2" will assume that it is an input
105            fileglob string. The input is the list of files that match the
106            fileglob.
107
108            See File::GlobMapper for more details.
109
110       If the $input_filename_or_reference parameter is any other type,
111       "undef" will be returned.
112
113       The $output_filename_or_reference parameter
114
115       The parameter $output_filename_or_reference is used to control the
116       destination of the compressed data. This parameter can take one of
117       these forms.
118
119       A filename
120            If the $output_filename_or_reference parameter is a simple scalar,
121            it is assumed to be a filename.  This file will be opened for
122            writing and the compressed data will be written to it.
123
124       A filehandle
125            If the $output_filename_or_reference parameter is a filehandle,
126            the compressed data will be written to it.  The string '-' can be
127            used as an alias for standard output.
128
129       A scalar reference
130            If $output_filename_or_reference is a scalar reference, the
131            compressed data will be stored in $$output_filename_or_reference.
132
133       An Array Reference
134            If $output_filename_or_reference is an array reference, the
135            compressed data will be pushed onto the array.
136
137       An Output FileGlob
138            If $output_filename_or_reference is a string that is delimited by
139            the characters "<" and ">" "bzip2" will assume that it is an
140            output fileglob string. The output is the list of files that match
141            the fileglob.
142
143            When $output_filename_or_reference is an fileglob string,
144            $input_filename_or_reference must also be a fileglob string.
145            Anything else is an error.
146
147            See File::GlobMapper for more details.
148
149       If the $output_filename_or_reference parameter is any other type,
150       "undef" will be returned.
151
152   Notes
153       When $input_filename_or_reference maps to multiple files/buffers and
154       $output_filename_or_reference is a single file/buffer the input
155       files/buffers will be stored in $output_filename_or_reference as a
156       concatenated series of compressed data streams.
157
158   Optional Parameters
159       The optional parameters for the one-shot function "bzip2" are (for the
160       most part) identical to those used with the OO interface defined in the
161       "Constructor Options" section. The exceptions are listed below
162
163       "AutoClose => 0|1"
164            This option applies to any input or output data streams to "bzip2"
165            that are filehandles.
166
167            If "AutoClose" is specified, and the value is true, it will result
168            in all input and/or output filehandles being closed once "bzip2"
169            has completed.
170
171            This parameter defaults to 0.
172
173       "BinModeIn => 0|1"
174            This option is now a no-op. All files will be read in binmode.
175
176       "Append => 0|1"
177            The behaviour of this option is dependent on the type of output
178            data stream.
179
180            •    A Buffer
181
182                 If "Append" is enabled, all compressed data will be append to
183                 the end of the output buffer. Otherwise the output buffer
184                 will be cleared before any compressed data is written to it.
185
186            •    A Filename
187
188                 If "Append" is enabled, the file will be opened in append
189                 mode. Otherwise the contents of the file, if any, will be
190                 truncated before any compressed data is written to it.
191
192            •    A Filehandle
193
194                 If "Append" is enabled, the filehandle will be positioned to
195                 the end of the file via a call to "seek" before any
196                 compressed data is written to it.  Otherwise the file pointer
197                 will not be moved.
198
199            When "Append" is specified, and set to true, it will append all
200            compressed data to the output data stream.
201
202            So when the output is a filehandle it will carry out a seek to the
203            eof before writing any compressed data. If the output is a
204            filename, it will be opened for appending. If the output is a
205            buffer, all compressed data will be appended to the existing
206            buffer.
207
208            Conversely when "Append" is not specified, or it is present and is
209            set to false, it will operate as follows.
210
211            When the output is a filename, it will truncate the contents of
212            the file before writing any compressed data. If the output is a
213            filehandle its position will not be changed. If the output is a
214            buffer, it will be wiped before any compressed data is output.
215
216            Defaults to 0.
217
218   Examples
219       Here are a few example that show the capabilities of the module.
220
221       Streaming
222
223       This very simple command line example demonstrates the streaming
224       capabilities of the module.  The code reads data from STDIN, compresses
225       it, and writes the compressed data to STDOUT.
226
227           $ echo hello world | perl -MIO::Compress::Bzip2=bzip2 -e 'bzip2 \*STDIN => \*STDOUT' >output.bz2
228
229       The special filename "-" can be used as a standin for both "\*STDIN"
230       and "\*STDOUT", so the above can be rewritten as
231
232           $ echo hello world | perl -MIO::Compress::Bzip2=bzip2 -e 'bzip2 "-" => "-"' >output.bz2
233
234       Compressing a file from the filesystem
235
236       To read the contents of the file "file1.txt" and write the compressed
237       data to the file "file1.txt.bz2".
238
239           use strict ;
240           use warnings ;
241           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
242
243           my $input = "file1.txt";
244           bzip2 $input => "$input.bz2"
245               or die "bzip2 failed: $Bzip2Error\n";
246
247       Reading from a Filehandle and writing to an in-memory buffer
248
249       To read from an existing Perl filehandle, $input, and write the
250       compressed data to a buffer, $buffer.
251
252           use strict ;
253           use warnings ;
254           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
255           use IO::File ;
256
257           my $input = IO::File->new( "<file1.txt" )
258               or die "Cannot open 'file1.txt': $!\n" ;
259           my $buffer ;
260           bzip2 $input => \$buffer
261               or die "bzip2 failed: $Bzip2Error\n";
262
263       Compressing multiple files
264
265       To compress all files in the directory "/my/home" that match "*.txt"
266       and store the compressed data in the same directory
267
268           use strict ;
269           use warnings ;
270           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
271
272           bzip2 '</my/home/*.txt>' => '<*.bz2>'
273               or die "bzip2 failed: $Bzip2Error\n";
274
275       and if you want to compress each file one at a time, this will do the
276       trick
277
278           use strict ;
279           use warnings ;
280           use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
281
282           for my $input ( glob "/my/home/*.txt" )
283           {
284               my $output = "$input.bz2" ;
285               bzip2 $input => $output
286                   or die "Error compressing '$input': $Bzip2Error\n";
287           }
288

OO Interface

290   Constructor
291       The format of the constructor for "IO::Compress::Bzip2" is shown below
292
293           my $z = IO::Compress::Bzip2->new( $output [,OPTS] )
294               or die "IO::Compress::Bzip2 failed: $Bzip2Error\n";
295
296       It returns an "IO::Compress::Bzip2" object on success and undef on
297       failure.  The variable $Bzip2Error will contain an error message on
298       failure.
299
300       If you are running Perl 5.005 or better the object, $z, returned from
301       IO::Compress::Bzip2 can be used exactly like an IO::File filehandle.
302       This means that all normal output file operations can be carried out
303       with $z.  For example, to write to a compressed file/buffer you can use
304       either of these forms
305
306           $z->print("hello world\n");
307           print $z "hello world\n";
308
309       The mandatory parameter $output is used to control the destination of
310       the compressed data. This parameter can take one of these forms.
311
312       A filename
313            If the $output parameter is a simple scalar, it is assumed to be a
314            filename. This file will be opened for writing and the compressed
315            data will be written to it.
316
317       A filehandle
318            If the $output parameter is a filehandle, the compressed data will
319            be written to it.  The string '-' can be used as an alias for
320            standard output.
321
322       A scalar reference
323            If $output is a scalar reference, the compressed data will be
324            stored in $$output.
325
326       If the $output parameter is any other type, "IO::Compress::Bzip2"::new
327       will return undef.
328
329   Constructor Options
330       "OPTS" is any combination of zero or more the following options:
331
332       "AutoClose => 0|1"
333            This option is only valid when the $output parameter is a
334            filehandle. If specified, and the value is true, it will result in
335            the $output being closed once either the "close" method is called
336            or the "IO::Compress::Bzip2" object is destroyed.
337
338            This parameter defaults to 0.
339
340       "Append => 0|1"
341            Opens $output in append mode.
342
343            The behaviour of this option is dependent on the type of $output.
344
345            •    A Buffer
346
347                 If $output is a buffer and "Append" is enabled, all
348                 compressed data will be append to the end of $output.
349                 Otherwise $output will be cleared before any data is written
350                 to it.
351
352            •    A Filename
353
354                 If $output is a filename and "Append" is enabled, the file
355                 will be opened in append mode. Otherwise the contents of the
356                 file, if any, will be truncated before any compressed data is
357                 written to it.
358
359            •    A Filehandle
360
361                 If $output is a filehandle, the file pointer will be
362                 positioned to the end of the file via a call to "seek" before
363                 any compressed data is written to it.  Otherwise the file
364                 pointer will not be moved.
365
366            This parameter defaults to 0.
367
368       "BlockSize100K => number"
369            Specify the number of 100K blocks bzip2 uses during compression.
370
371            Valid values are from 1 to 9, where 9 is best compression.
372
373            The default is 1.
374
375       "WorkFactor => number"
376            Specifies how much effort bzip2 should take before resorting to a
377            slower fallback compression algorithm.
378
379            Valid values range from 0 to 250, where 0 means use the default
380            value 30.
381
382            The default is 0.
383
384       "Strict => 0|1"
385            This is a placeholder option.
386
387   Examples
388       TODO
389

Methods

391   print
392       Usage is
393
394           $z->print($data)
395           print $z $data
396
397       Compresses and outputs the contents of the $data parameter. This has
398       the same behaviour as the "print" built-in.
399
400       Returns true if successful.
401
402   printf
403       Usage is
404
405           $z->printf($format, $data)
406           printf $z $format, $data
407
408       Compresses and outputs the contents of the $data parameter.
409
410       Returns true if successful.
411
412   syswrite
413       Usage is
414
415           $z->syswrite $data
416           $z->syswrite $data, $length
417           $z->syswrite $data, $length, $offset
418
419       Compresses and outputs the contents of the $data parameter.
420
421       Returns the number of uncompressed bytes written, or "undef" if
422       unsuccessful.
423
424   write
425       Usage is
426
427           $z->write $data
428           $z->write $data, $length
429           $z->write $data, $length, $offset
430
431       Compresses and outputs the contents of the $data parameter.
432
433       Returns the number of uncompressed bytes written, or "undef" if
434       unsuccessful.
435
436   flush
437       Usage is
438
439           $z->flush;
440
441       Flushes any pending compressed data to the output file/buffer.
442
443       TODO
444
445       Returns true on success.
446
447   tell
448       Usage is
449
450           $z->tell()
451           tell $z
452
453       Returns the uncompressed file offset.
454
455   eof
456       Usage is
457
458           $z->eof();
459           eof($z);
460
461       Returns true if the "close" method has been called.
462
463   seek
464           $z->seek($position, $whence);
465           seek($z, $position, $whence);
466
467       Provides a sub-set of the "seek" functionality, with the restriction
468       that it is only legal to seek forward in the output file/buffer.  It is
469       a fatal error to attempt to seek backward.
470
471       Empty parts of the file/buffer will have NULL (0x00) bytes written to
472       them.
473
474       The $whence parameter takes one the usual values, namely SEEK_SET,
475       SEEK_CUR or SEEK_END.
476
477       Returns 1 on success, 0 on failure.
478
479   binmode
480       Usage is
481
482           $z->binmode
483           binmode $z ;
484
485       This is a noop provided for completeness.
486
487   opened
488           $z->opened()
489
490       Returns true if the object currently refers to a opened file/buffer.
491
492   autoflush
493           my $prev = $z->autoflush()
494           my $prev = $z->autoflush(EXPR)
495
496       If the $z object is associated with a file or a filehandle, this method
497       returns the current autoflush setting for the underlying filehandle. If
498       "EXPR" is present, and is non-zero, it will enable flushing after every
499       write/print operation.
500
501       If $z is associated with a buffer, this method has no effect and always
502       returns "undef".
503
504       Note that the special variable $| cannot be used to set or retrieve the
505       autoflush setting.
506
507   input_line_number
508           $z->input_line_number()
509           $z->input_line_number(EXPR)
510
511       This method always returns "undef" when compressing.
512
513   fileno
514           $z->fileno()
515           fileno($z)
516
517       If the $z object is associated with a file or a filehandle, "fileno"
518       will return the underlying file descriptor. Once the "close" method is
519       called "fileno" will return "undef".
520
521       If the $z object is associated with a buffer, this method will return
522       "undef".
523
524   close
525           $z->close() ;
526           close $z ;
527
528       Flushes any pending compressed data and then closes the output
529       file/buffer.
530
531       For most versions of Perl this method will be automatically invoked if
532       the IO::Compress::Bzip2 object is destroyed (either explicitly or by
533       the variable with the reference to the object going out of scope). The
534       exceptions are Perl versions 5.005 through 5.00504 and 5.8.0. In these
535       cases, the "close" method will be called automatically, but not until
536       global destruction of all live objects when the program is terminating.
537
538       Therefore, if you want your scripts to be able to run on all versions
539       of Perl, you should call "close" explicitly and not rely on automatic
540       closing.
541
542       Returns true on success, otherwise 0.
543
544       If the "AutoClose" option has been enabled when the IO::Compress::Bzip2
545       object was created, and the object is associated with a file, the
546       underlying file will also be closed.
547
548   newStream([OPTS])
549       Usage is
550
551           $z->newStream( [OPTS] )
552
553       Closes the current compressed data stream and starts a new one.
554
555       OPTS consists of any of the options that are available when creating
556       the $z object.
557
558       See the "Constructor Options" section for more details.
559

Importing

561       No symbolic constants are required by IO::Compress::Bzip2 at present.
562
563       :all Imports "bzip2" and $Bzip2Error.  Same as doing this
564
565                use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
566

EXAMPLES

568   Apache::GZip Revisited
569       See IO::Compress::FAQ
570
571   Working with Net::FTP
572       See IO::Compress::FAQ
573

SUPPORT

575       General feedback/questions/bug reports should be sent to
576       <https://github.com/pmqs/IO-Compress/issues> (preferred) or
577       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Compress>.
578

SEE ALSO

580       Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip,
581       IO::Compress::Deflate, IO::Uncompress::Inflate,
582       IO::Compress::RawDeflate, IO::Uncompress::RawInflate,
583       IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma,
584       IO::Compress::Xz, IO::Uncompress::UnXz, IO::Compress::Lzip,
585       IO::Uncompress::UnLzip, IO::Compress::Lzop, IO::Uncompress::UnLzop,
586       IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Compress::Zstd,
587       IO::Uncompress::UnZstd, IO::Uncompress::AnyInflate,
588       IO::Uncompress::AnyUncompress
589
590       IO::Compress::FAQ
591
592       File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
593
594       The primary site for the bzip2 program is
595       <https://sourceware.org/bzip2/>.
596
597       See the module Compress::Bzip2
598

AUTHOR

600       This module was written by Paul Marquess, "pmqs@cpan.org".
601

MODIFICATION HISTORY

603       See the Changes file.
604
606       Copyright (c) 2005-2021 Paul Marquess. All rights reserved.
607
608       This program is free software; you can redistribute it and/or modify it
609       under the same terms as Perl itself.
610
611
612
613perl v5.32.1                      2021-03-01            IO::Compress::Bzip2(3)
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