IO::Compress::Lzop - Write lzop files/buffers
use IO::Compress::Lzop qw(lzop $LzopError) ;
my $status = lzop $input => $output [,OPTS]
or die "lzop failed: $LzopError\n";
my $z = new IO::Compress::Lzop $output [,OPTS]
or die "lzop failed: $LzopError\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() ;
$LzopError ;
# 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 lzop compressed data to files or buffer.
For reading lzop files/buffers, see the companion module IO::Uncompress::UnLzop.
A top-level function, lzop, 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::Lzop qw(lzop $LzopError) ;
lzop $input => $output [,OPTS]
or die "lzop failed: $LzopError\n";
The functional interface needs Perl5.005 or better.
lzop expects at least two parameters, $input and $output.
$input parameterThe parameter, $input, is used to define the source of the uncompressed data.
It can take one of the following forms:
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.
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.
If $input is a scalar reference, the input data will be read from $$input.
If $input is an array reference, each element in the array must be a filename.
The input data will be read from each file in turn.
The complete array will be walked to ensure that it only contains valid filenames before any data is compressed.
If $input is a string that is delimited by the characters "<" and ">" lzop will assume that it is an input fileglob string. The input is the list of files that match the fileglob.
If the fileglob does not match any files ...
See File::GlobMapper for more details.
If the $input parameter is any other type, undef will be returned.
In addition, if $input is a simple filename, the default values for the Name and Time options will be sourced from that file.
If you do not want to use these defaults they can be overridden by explicitly setting the Name and Time options or by setting the Minimal parameter.
$output parameterThe parameter $output is used to control the destination of the compressed data. This parameter can take one of these forms.
If the $output parameter is a simple scalar, it is assumed to be a filename. This file will be opened for writing and the compressed data will be written to it.
If the $output parameter is a filehandle, the compressed data will be written to it. The string '-' can be used as an alias for standard output.
If $output is a scalar reference, the compressed data will be stored in $$output.
If $output is an array reference, the compressed data will be pushed onto the array.
If $output is a string that is delimited by the characters "<" and ">" lzop 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.
When $input maps to multiple files/buffers and $output is a single file/buffer the input files/buffers will each be stored in $output as a distinct entry.
Unless specified below, the optional parameters for lzop, OPTS, are the same as those used with the OO interface defined in the "Constructor Options" section below.
AutoClose => 0|1This option applies to any input or output data streams to lzop 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 lzop has completed.
This parameter defaults to 0.
BinModeIn => 0|1When reading from a file or filehandle, set binmode before reading.
Defaults to 0.
Append => 0|1TODO
To read the contents of the file file1.txt and write the compressed data to the file file1.txt.lzo.
use strict ;
use warnings ;
use IO::Compress::Lzop qw(lzop $LzopError) ;
my $input = "file1.txt";
lzop $input => "$input.lzo"
or die "lzop failed: $LzopError\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::Lzop qw(lzop $LzopError) ;
use IO::File ;
my $input = new IO::File "<file1.txt"
or die "Cannot open 'file1.txt': $!\n" ;
my $buffer ;
lzop $input => \$buffer
or die "lzop failed: $LzopError\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::Lzop qw(lzop $LzopError) ;
lzop '</my/home/*.txt>' => '<*.lzo>'
or die "lzop failed: $LzopError\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::Lzop qw(lzop $LzopError) ;
for my $input ( glob "/my/home/*.txt" )
{
my $output = "$input.lzo" ;
lzop $input => $output
or die "Error compressing '$input': $LzopError\n";
}
The format of the constructor for IO::Compress::Lzop is shown below
my $z = new IO::Compress::Lzop $output [,OPTS]
or die "IO::Compress::Lzop failed: $LzopError\n";
It returns an IO::Compress::Lzop object on success and undef on failure. The variable $LzopError will contain an error message on failure.
If you are running Perl 5.005 or better the object, $z, returned from IO::Compress::Lzop 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 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.
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.
If $output is a scalar reference, the compressed data will be stored in $$output.
If the $output parameter is any other type, IO::Compress::Lzop::new will return undef.
OPTS is any combination of the following options:
AutoClose => 0|1This 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::Lzop object is destroyed.
This parameter defaults to 0.
Append => 0|1Opens $output in append mode.
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 if $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.
Name => $stringStores the contents of $string in the name field lzop header.
If Name is not specified, no gzip NAME field will be created.
Time => $numberSets the Time field in the lzop header to $number.
This field defaults to the time the IO::Compress::Lzop object was created if this option is not specified.
TODO
TODO
TODO
Creates the smallest possible lzop file/buffer.
Disables the creation of all checksums.
No Name is stored.
TODO
Strict => 0|1This is a placeholder option.
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 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::Lzop 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::Lzop 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 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::Lzop at present.
Imports lzop and $LzopError. Same as doing this
use IO::Compress::Lzop qw(lzop $LzopError) ;
Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip, IO::Compress::Deflate, IO::Uncompress::Inflate, IO::Compress::RawDeflate, IO::Uncompress::RawInflate, IO::Compress::Bzip2, IO::Uncompress::Bunzip2, IO::Uncompress::UnLzop, IO::Compress::Lzf, IO::Uncompress::UnLzf, IO::Uncompress::AnyInflate, IO::Uncompress::AnyUncompress
File::GlobMapper, Archive::Zip, Archive::Tar, IO::Zlib
This module was written by Paul Marquess, pmqs@cpan.org.
See the Changes file.
Copyright (c) 2005-2009 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.
