IO::Unc...:Bunzip2(3)

📦 version 2.220.0, in opensuse-leap 16.0

🎀 NAME 🎀

Okay bestie, meet IO::Uncompress::Bunzip2 — she reads bzip2 files/buffers. That’s the manual name and the whole assignment, fr fr. This is the section 3 user-contributed Perl documentation vibe, folded in right here so we don’t gotta copy the header line like a boring person.

✨ SYNOPSIS ✨

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

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

my $z = IO::Uncompress::Bunzip2->new( $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 gives you a Perl interface that lets you read bzip2 files/buffers. That’s the tea. 🫖

For writing bzip2 files/buffers, go see her companion module, IO::Compress::Bzip2. Iconic duo behavior, honestly.

🌸 Functional Interface 🌸

There’s a top-level function called bunzip2 that handles the “one-shot” uncompression between buffers and/or files. If you want finer control over the uncompression process, peek at the “OO Interface” section. Main character options, iykyk.

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. Vintage but valid. 💅

🌀 `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, plus zero or more optional parameters — those live in “Optional Parameters” below.

💖 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 these forms:

A filename — If $input_filename_or_reference 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 $input_filename_or_reference 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. Very thorough, very “let me check the group chat before we go out.” 🧚

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 $output_filename_or_reference 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 $output_filename_or_reference 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 a fileglob string, $input_filename_or_reference must also be a fileglob string. Anything else is an error. No cap, that’s the rule.

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. It’s giving “everyone pile into the same limo.” 🚗✨

🎛️ Optional Parameters 🎛️

The optional parameters for the one-shot function bunzip2 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 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 — This option is now a no-op. All files will be written in binmode. She said “been there, done that, binmode forever.” 💅
Append => 0|1 — The behaviour of this option is dependent on the type of output data stream.
- 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.
- 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.
- 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.

🧪 OneShot 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 = IO::File->new( "<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 ✨

Okay bestie, now we’re in the object-oriented era of this module. The constructor format is literally this:

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

It takes one mandatory parameter, $input — defined below — and zero or more OPTS, defined in “Constructor Options”.

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

If you’re running Perl 5.005 or better, the object $z returned from IO::Uncompress::Bunzip2 can be used exactly like an IO::File filehandle. That means 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>;

Below is a simple example of using the OO interface to read the compressed file myfile.bz2 and write its contents to stdout.

my $filename = "myfile.bz2";
my $z = IO::Uncompress::Bunzip2->new($filename)
    or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";

while (<$z>) {
    print $_;
}
$z->close();

See “EXAMPLES” for further examples.

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 🛠️

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

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

The constructor takes one mandatory parameter, $input, defined below, and zero or more OPTS, defined in “Constructor Options”.

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>;

Below is a simple example of using the OO interface to read the compressed file myfile.bz2 and write its contents to stdout.

my $filename = "myfile.bz2";
my $z = IO::Uncompress::Bunzip2->new($filename)
    or die "IO::Uncompress::Bunzip2 failed: $Bunzip2Error\n";

while (<$z>) {
    print $_;
}
$z->close();

See “EXAMPLES” for further examples.

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.

Methods ✨

okay bestie, this is where the $z object actually starts doing stuff. buckle up 💅

read 💅

Usage is literally:

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

Reads a block of compressed data — the size of that compressed block is set by the Buffer option in the constructor — uncompresses it, and writes any uncompressed data into $buffer. If the Append parameter was set in the constructor, the uncompressed data gets appended to the $buffer parameter. Otherwise $buffer gets overwritten.

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

read 💅 (the `$length` glow-up)

Usage is:

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

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

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

The main difference between this form of read and the previous one is that this one will attempt to return exactly $length bytes. The only circumstances where it won't are 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 using $/ (or $INPUT_RECORD_SEPARATOR, or $RS when English is in use) to determine what counts as an end of line. Paragraph mode, record mode, and file slurp mode are all supported, no cap.

getc 🦋

Usage is:

$char = $z->getc()

Reads a single character.

ungetc 🌸

Usage is:

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

That's the whole vibe for this one, bestie.

getHeaderInfo ✨

Usage is:

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

This method returns either a hash reference (in scalar context) or a list of hash references (in array context) containing 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 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, bestie. do not test this for fun 😭

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 of 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 an 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.

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 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.

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.

AUTHOR 💜

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

MODIFICATION HISTORY 📝

See the Changes file.

COPYRIGHT AND LICENSE 👑

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

That's the whole page, bestie 💖 source/version vibes: perl v5.42.0, dated 2026-05-17. now go uncompress something iconic. periodt 🎀

📦 where this page comes from

opensuse-leap 16.0: perl-IO-Compress 2.220.0-bp160.1.1 · Artistic-1.0 OR GPL-1.0-or-later
💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on 2026-11-04: a language model's rewrite of the original, under its terms

IO::Unc...:Bunzip2(3)

🎀 NAME 🎀

✨ SYNOPSIS ✨

🦋 DESCRIPTION 🦋

🌸 Functional Interface 🌸

🌀 bunzip2 $input_filename_or_reference => $output_filename_or_reference [, OPTS]

💖 The $input_filename_or_reference parameter 💖

💜 The $output_filename_or_reference parameter 💜

📝 Notes 📝

🎛️ Optional Parameters 🎛️

🧪 OneShot Examples 🧪

✨ OO Interface ✨

📁 A filename

🫶 A filehandle

🎀 A scalar reference

🛠️ Constructor 🛠️

🎛️ Constructor Options 🎛️

Methods ✨

read 💅

read 💅 (the $length glow-up)

getline 🎀

getc 🦋

ungetc 🌸

getHeaderInfo ✨

tell 💫

eof 🫶

seek 👑

binmode 🎀

opened 🌈

autoflush 💅

input_line_number 🧚

fileno 🍓

close 💖

nextStream 🔥

trailingData 🌟

Importing 🛍️

EXAMPLES 💫

Working with Net::FTP 🛰️

SUPPORT 🫶

SEE ALSO 👀

AUTHOR 💜

MODIFICATION HISTORY 📝

COPYRIGHT AND LICENSE 👑

🌀 `bunzip2 $input_filename_or_reference => $output_filename_or_reference [, OPTS]`

💖 The `$input_filename_or_reference` parameter 💖

💜 The `$output_filename_or_reference` parameter 💜

read 💅 (the `$length` glow-up)