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 = 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 ;
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 => $output [,OPTS]
or die "bzip2 failed: $Bzip2Error\n";
The functional interface needs Perl5.005 or better.
"bzip2" expects at least two parameters, $input and $output.
The $input parameter
The parameter, $input, is used to define the source of the uncompressed data.
It can take one of the following forms:
- A filename
- If the $input 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 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 is a scalar reference, the input data will be
read from $$input.
- An array reference
- If $input is an array reference, each element in the array
must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only contains valid
filenames before any data is compressed.
- An Input FileGlob string
- If $input is a string that is delimited by the characters
"<" and ">" "bzip2" will assume that
it is an input fileglob string. The input is the list of files that
match the fileglob.
If the fileglob does not match any files ...
See File::GlobMapper for more details.
If the $input parameter is any other type, "undef" will be returned.
The $output parameter
The parameter $output is used to control the destination of the compressed data.
This parameter can take one of these forms.
- A filename
- If the $output parameter is a simple scalar, it is assumed
to be a filename. This file will be opened for writing and the compressed
data will be written to it.
- A filehandle
- If the $output parameter is a filehandle, the compressed
data will be written to it. The string '-' can be used as an alias for
standard output.
- A scalar reference
- If $output is a scalar reference, the compressed data will
be stored in $$output.
- An Array Reference
- If $output is an array reference, the compressed data will
be pushed onto the array.
- An Output FileGlob
- If $output 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 is an fileglob string, $input must also be a fileglob string.
Anything else is an error.
If the $output parameter is any other type, "undef" will be returned.
Notes¶
When $input maps to multiple files/buffers and $output is a single file/buffer
the input files/buffers will be stored in $output as a concatenated series of
compressed data streams.
Optional Parameters¶
Unless specified below, the optional parameters for "bzip2",
"OPTS", are the same as those used with the OO interface defined in
the "Constructor Options" section 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"
- When reading from a file or filehandle, set
"binmode" before reading.
Defaults to 0.
- "Append => 0|1"
- TODO
Examples¶
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";
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";
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 = 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.
- 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 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 if $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.
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.
$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 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 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 this 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::Bzip2::FAQ
Working with Net::FTP¶
See IO::Compress::Bzip2::FAQ
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::Lzop,
IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf,
IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress
Compress::Zlib::FAQ
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
The primary site for the bzip2 program is
http://www.bzip.org.
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) 2005-2008 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.