| IO::Compress::Bzip2(3perl) | Perl Programmers Reference Guide | IO::Compress::Bzip2(3perl) |
IO::Compress::Bzip2 - Write bzip2 files/buffers
use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
my $status = bzip2 $input => $output [,OPTS]
or die "bzip2 failed: $Bzip2Error\n";
my $z = new IO::Compress::Bzip2 $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 ;
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.
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" 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:
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.
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.
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.
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.
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
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.
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.
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.
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.
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 = new IO::File "<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";
}
The format of the constructor for "IO::Compress::Bzip2" is shown below
my $z = new IO::Compress::Bzip2 $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.
If the $output parameter is any other type, "IO::Compress::Bzip2"::new will return undef.
"OPTS" is any combination of zero or more the following options:
This parameter defaults to 0.
The behaviour of this option is dependent on the type of $output.
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.
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.
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.
Valid values are from 1 to 9, where 9 is best compression.
The default is 1.
Valid values range from 0 to 250, where 0 means use the default value 30.
The default is 0.
TODO
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.
Usage is
$z->printf($format, $data)
printf $z $format, $data
Compresses and outputs the contents of the $data parameter.
Returns true if successful.
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.
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.
Usage is
$z->flush;
Flushes any pending compressed data to the output file/buffer.
TODO
Returns true on success.
Usage is
$z->tell()
tell $z
Returns the uncompressed file offset.
Usage is
$z->eof();
eof($z);
Returns true if the "close" method has been called.
$z->seek($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.
Usage is
$z->binmode
binmode $z ;
This is a noop provided for completeness.
$z->opened()
Returns true if the object currently refers to a opened file/buffer.
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.
$z->input_line_number()
$z->input_line_number(EXPR)
This method always returns "undef" when compressing.
$z->fileno()
fileno($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".
$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.
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.
No symbolic constants are required by this IO::Compress::Bzip2 at present.
use IO::Compress::Bzip2 qw(bzip2 $Bzip2Error) ;
See IO::Compress::FAQ
See IO::Compress::FAQ
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>.
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
This module was written by Paul Marquess, "pmqs@cpan.org".
See the Changes file.
Copyright (c) 2005-2019 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.
| 2023-11-25 | perl v5.32.1 |