UNIX ON-LINE Man Pages - Die Onlinehilfe

Die Syntax von Unixbefehlen wird in den entsprechenden Manpages dokumentiert. Hier können Sie diese Onlinehilfe für viele Standardbefehle abrufen.

Suchoptionen:
Seiten auflisten, welche beginnen mit:
A   B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X   Y   Z   ALPHA   NUM   ANDERE   ALLE
IO::Compress::Deflate(3Perl Programmers Reference GuIO::Compress::Deflate(3pm)

NAME
       IO::Compress::Deflate - Write RFC 1950 files/buffers

SYNOPSIS
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

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

           my $z = new IO::Compress::Deflate $output [,OPTS]
               or die "deflate failed: $DeflateError\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->deflateParams();

           $z->close() ;

           $DeflateError ;

           # 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 compressed
       data to files or buffer as defined in RFC 1950.

       For reading RFC 1950 files/buffers, see the companion module
       IO::Uncompress::Inflate.

Functional Interface
       A top-level function, "deflate", 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::Deflate qw(deflate $DeflateError) ;

           deflate $input => $output [,OPTS]
               or die "deflate failed: $DeflateError\n";

       The functional interface needs Perl5.005 or better.

   deflate $input => $output [, OPTS]
       "deflate" 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
            ">" "deflate" 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
            ">" "deflate" 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 "deflate", "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
            "deflate" 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 "deflate"
            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"
            The behaviour of this option is dependent on the type of output
            data stream.

            o    A Buffer

                 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.

            o    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 compressed data is written to it.

            o    A Filehandle

                 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 appened 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.

   Examples
       To read the contents of the file "file1.txt" and write the compressed
       data to the file "file1.txt.1950".

           use strict ;
           use warnings ;
           use IO::Compress::Deflate qw(deflate $DeflateError) ;

           my $input = "file1.txt";
           deflate $input => "$input.1950"
               or die "deflate failed: $DeflateError\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::Deflate qw(deflate $DeflateError) ;
           use IO::File ;

           my $input = new IO::File "<file1.txt"
               or die "Cannot open 'file1.txt': $!\n" ;
           my $buffer ;
           deflate $input => \$buffer
               or die "deflate failed: $DeflateError\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::Deflate qw(deflate $DeflateError) ;

           deflate '</my/home/*.txt>' => '<*.1950>'
               or die "deflate failed: $DeflateError\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::Deflate qw(deflate $DeflateError) ;

           for my $input ( glob "/my/home/*.txt" )
           {
               my $output = "$input.1950" ;
               deflate $input => $output
                   or die "Error compressing '$input': $DeflateError\n";
           }

OO Interface
   Constructor
       The format of the constructor for "IO::Compress::Deflate" is shown
       below

           my $z = new IO::Compress::Deflate $output [,OPTS]
               or die "IO::Compress::Deflate failed: $DeflateError\n";

       It returns an "IO::Compress::Deflate" object on success and undef on
       failure.  The variable $DeflateError will contain an error message on
       failure.

       If you are running Perl 5.005 or better the object, $z, returned from
       IO::Compress::Deflate 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::Deflate"::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::Deflate" 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.

            o    A Buffer

                 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.

            o    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.

            o    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.

       "Merge => 0|1"
            This option is used to compress input data and append it to an
            existing compressed data stream in $output. The end result is a
            single compressed data stream stored in $output.

            It is a fatal error to attempt to use this option when $output is
            not an RFC 1950 data stream.

            There are a number of other limitations with the "Merge" option:

            1.   This module needs to have been built with zlib 1.2.1 or
                 better to work. A fatal error will be thrown if "Merge" is
                 used with an older version of zlib.

            2.   If $output is a file or a filehandle, it must be seekable.

            This parameter defaults to 0.

       -Level
            Defines the compression level used by zlib. The value should
            either be a number between 0 and 9 (0 means no compression and 9
            is maximum compression), or one of the symbolic constants defined
            below.

               Z_NO_COMPRESSION
               Z_BEST_SPEED
               Z_BEST_COMPRESSION
               Z_DEFAULT_COMPRESSION

            The default is Z_DEFAULT_COMPRESSION.

            Note, these constants are not imported by "IO::Compress::Deflate"
            by default.

                use IO::Compress::Deflate qw(:strategy);
                use IO::Compress::Deflate qw(:constants);
                use IO::Compress::Deflate qw(:all);

       -Strategy
            Defines the strategy used to tune the compression. Use one of the
            symbolic constants defined below.

               Z_FILTERED
               Z_HUFFMAN_ONLY
               Z_RLE
               Z_FIXED
               Z_DEFAULT_STRATEGY

            The default is Z_DEFAULT_STRATEGY.

       "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;
           $z->flush($flush_type);

       Flushes any pending compressed data to the output file/buffer.

       This method takes an optional parameter, $flush_type, that controls how
       the flushing will be carried out. By default the $flush_type used is
       "Z_FINISH". Other valid values for $flush_type are "Z_NO_FLUSH",
       "Z_SYNC_FLUSH", "Z_FULL_FLUSH" and "Z_BLOCK". It is strongly
       recommended that you only set the "flush_type" parameter if you fully
       understand the implications of what it does - overuse of "flush" can
       seriously degrade the level of compression achieved. See the "zlib"
       documentation for details.

       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.

   input_line_number
           $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::Deflate 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::Deflate 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.

   deflateParams
       Usage is

           $z->deflateParams

       TODO

Importing
       A number of symbolic constants are required by some methods in
       "IO::Compress::Deflate". None are imported by default.

       :all Imports "deflate", $DeflateError and all symbolic constants that
            can be used by "IO::Compress::Deflate". Same as doing this

                use IO::Compress::Deflate qw(deflate $DeflateError :constants) ;

       :constants
            Import all symbolic constants. Same as doing this

                use IO::Compress::Deflate qw(:flush :level :strategy) ;

       :flush
            These symbolic constants are used by the "flush" method.

                Z_NO_FLUSH
                Z_PARTIAL_FLUSH
                Z_SYNC_FLUSH
                Z_FULL_FLUSH
                Z_FINISH
                Z_BLOCK

       :level
            These symbolic constants are used by the "Level" option in the
            constructor.

                Z_NO_COMPRESSION
                Z_BEST_SPEED
                Z_BEST_COMPRESSION
                Z_DEFAULT_COMPRESSION

       :strategy
            These symbolic constants are used by the "Strategy" option in the
            constructor.

                Z_FILTERED
                Z_HUFFMAN_ONLY
                Z_RLE
                Z_FIXED
                Z_DEFAULT_STRATEGY

EXAMPLES
   Apache::GZip Revisited
       See IO::Compress::FAQ

   Working with Net::FTP
       See IO::Compress::FAQ

SEE ALSO
       Compress::Zlib, IO::Compress::Gzip, IO::Uncompress::Gunzip,
       IO::Uncompress::Inflate, IO::Compress::RawDeflate,
       IO::Uncompress::RawInflate, IO::Compress::Bzip2,
       IO::Uncompress::Bunzip2, IO::Compress::Lzma, IO::Uncompress::UnLzma,
       IO::Compress::Xz, IO::Uncompress::UnXz, 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

       For RFC 1950, 1951 and 1952 see http://www.faqs.org/rfcs/rfc1950.html,
       http://www.faqs.org/rfcs/rfc1951.html and
       http://www.faqs.org/rfcs/rfc1952.html

       The zlib compression library was written by Jean-loup Gailly
       gzip@prep.ai.mit.edu and Mark Adler madler@alumni.caltech.edu.

       The primary site for the zlib compression library is
       http://www.zlib.org.

       The primary site for gzip is http://www.gzip.org.

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

MODIFICATION HISTORY
       See the Changes file.

COPYRIGHT AND LICENSE
       Copyright (c) 2005-2010 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.

perl v5.12.1                      2010-04-26        IO::Compress::Deflate(3pm)
 

Scannen Sie den Barcode um die Webseite zu öffnen


Quelle: http://www.trinler.net/de/service/doc/linux/man.html?command=IO%3A%3ACompress%3A%3ADeflate
Gedruckt am: 11.12.2017 15:59 GMT+0100 (2017-12-11T15:59:03+01:00)