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IO::Co...::Gzip(3perl)  Perl Programmers Reference Guide IO::Co...::Gzip(3perl)

NAME
       IO::Compress::Gzip - Write RFC 1952 files/buffers

SYNOPSIS
           use IO::Compress::Gzip qw(gzip $GzipError) ;

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

           my $z = IO::Compress::Gzip->new( $output [,OPTS] )
               or die "gzip failed: $GzipError\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() ;

           $GzipError ;

           # 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 1952.

       All the gzip headers defined in RFC 1952 can be created using this
       module.

       For reading RFC 1952 files/buffers, see the companion module
       IO::Uncompress::Gunzip.

Functional Interface
       A top-level function, "gzip", 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::Gzip qw(gzip $GzipError) ;

           gzip $input_filename_or_reference => $output_filename_or_reference [,OPTS]
               or die "gzip failed: $GzipError\n";

       The functional interface needs Perl5.005 or better.

   gzip $input_filename_or_reference => $output_filename_or_reference [, OPTS]
       "gzip" 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:

       A filename
            If  the  $input_filename_or_reference 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_filename_or_reference 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_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 compressed.

       An Input FileGlob string
            If  $input_filename_or_reference  is  a string that is delimited by
            the characters "<" and ">" "gzip" 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.

       In addition, if $input_filename_or_reference 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.

       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.

       A filename
            If  the $output_filename_or_reference 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_filename_or_reference 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_filename_or_reference  is  a  scalar   reference,   the
            compressed data will be stored in $$output_filename_or_reference.

       An Array Reference
            If   $output_filename_or_reference   is  an  array  reference,  the
            compressed 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 ">" "gzip" 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   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.

   Notes
       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.

   Optional Parameters
       The  optional  parameters  for the one-shot function "gzip" 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 "gzip"
            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 "gzip" has
            completed.

            This parameter defaults to 0.

       "BinModeIn => 0|1"
            This option is now a no-op. All files will be read in binmode.

       "Append => 0|1"
            The  behaviour  of  this  option is dependent on the type of output
            data stream.

            •    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.

            •    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.

            •    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  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.

   Oneshot Examples
       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::Gzip=gzip -e 'gzip \*STDIN => \*STDOUT' >output.gz

       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::Gzip=gzip -e 'gzip "-" => "-"' >output.gz

       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.gz".

           use strict ;
           use warnings ;
           use IO::Compress::Gzip qw(gzip $GzipError) ;

           my $input = "file1.txt";
           gzip $input => "$input.gz"
               or die "gzip failed: $GzipError\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::Gzip qw(gzip $GzipError) ;
           use IO::File ;

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

           gzip '</my/home/*.txt>' => '<*.gz>'
               or die "gzip failed: $GzipError\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::Gzip qw(gzip $GzipError) ;

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

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

           my $z = IO::Compress::Gzip->new( $output [,OPTS] )
               or die "IO::Compress::Gzip failed: $GzipError\n";

       The  constructor  takes  one mandatory parameter, $output, defined below
       and zero or more "OPTS", defined in "Constructor Options".

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

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

       Below is a simple exaple of using the OO interface to create  an  output
       file "myfile.gz" and write some data to it.

           my $filename = "myfile.gz";
           my $z = IO::Compress::Gzip->new($filename)
               or die "IO::Compress::Gzip failed: $GzipError\n";

           $z->print("abcde");
           $z->close();

       See the "Examples" for more.

       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::Gzip"::new
       will return undef.

   Constructor Options
       "OPTS" is any combination of zero or more 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::Gzip" 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 of $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.

       "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 1952 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::Gzip"  by
            default.

                use IO::Compress::Gzip qw(:strategy);
                use IO::Compress::Gzip qw(:constants);
                use IO::Compress::Gzip 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.

       "Minimal => 0|1"
            If specified, this option will force the creation of  the  smallest
            possible  compliant gzip header (which is exactly 10 bytes long) as
            defined in RFC 1952.

            See the section titled "Compliance" in RFC 1952 for a definition of
            the values used for the fields in the gzip header.

            All other parameters that control the content of  the  gzip  header
            will be ignored if this parameter is set to 1.

            This parameter defaults to 0.

       "Comment => $comment"
            Stores  the  contents  of $comment in the COMMENT field in the gzip
            header.  By default, no comment field is written to the gzip file.

            If the "-Strict" option is enabled, the comment can only consist of
            ISO 8859-1 characters plus line feed.

            If the "-Strict" option is disabled, the comment field can  contain
            any  character except NULL. If any null characters are present, the
            field will be truncated at the first NULL.

       "Name => $string"
            Stores the contents of $string in the gzip NAME  header  field.  If
            "Name" is not specified, no gzip NAME field will be created.

            If the "-Strict" option is enabled, $string can only consist of ISO
            8859-1 characters.

            If  "-Strict"  is  disabled, then $string can contain any character
            except NULL. If any null characters are present, the field will  be
            truncated at the first NULL.

       "Time => $number"
            Sets the MTIME field in the gzip header to $number.

            This field defaults to the time the "IO::Compress::Gzip" object was
            created if this option is not specified.

       "TextFlag => 0|1"
            This  parameter  controls  the  setting of the FLG.FTEXT bit in the
            gzip header. It is used to signal that the data stored in the  gzip
            file/buffer is probably text.

            The default is 0.

       "HeaderCRC => 0|1"
            When  true  this  parameter  will set the FLG.FHCRC bit to 1 in the
            gzip header and set the CRC16  header  field  to  the  CRC  of  the
            complete gzip header except the CRC16 field itself.

            Note  that  gzip  files  created with the "HeaderCRC" flag set to 1
            cannot be read  by  most,  if  not  all,  of  the  standard  gunzip
            utilities,  most  notably  gzip version 1.2.4. You should therefore
            avoid using this option if you want to maximize the portability  of
            your gzip files.

            This parameter defaults to 0.

       "OS_Code => $value"
            Stores  $value  in the gzip OS header field. A number between 0 and
            255 is valid.

            If not specified, this parameter defaults to the  OS  code  of  the
            Operating System this module was built on. The value 3 is used as a
            catch-all for all Unix variants and unknown Operating Systems.

       "ExtraField => $data"
            This  parameter  allows  additional  metadata  to  be stored in the
            ExtraField in the gzip header. An  RFC  1952  compliant  ExtraField
            consists of zero or more subfields. Each subfield consists of a two
            byte header followed by the subfield data.

            The  list  of  subfields  can  be  supplied in any of the following
            formats

                -ExtraField => [$id1, $data1,
                                $id2, $data2,
                                 ...
                               ]
                -ExtraField => [ [$id1 => $data1],
                                 [$id2 => $data2],
                                 ...
                               ]
                -ExtraField => { $id1 => $data1,
                                 $id2 => $data2,
                                 ...
                               }

            Where $id1, $id2 are two byte subfield ID's. The second byte of the
            ID cannot be 0, unless the "Strict" option has been disabled.

            If you use the hash syntax, you have no control over the  order  in
            which the ExtraSubFields are stored, plus you cannot have SubFields
            with duplicate ID.

            Alternatively  the  list  of subfields can by supplied as a scalar,
            thus

                -ExtraField => $rawdata

            If you use the raw format, and  the  "Strict"  option  is  enabled,
            "IO::Compress::Gzip"  will  check that $rawdata consists of zero or
            more conformant sub-fields. When "Strict" is disabled, $rawdata can
            consist of any arbitrary byte stream.

            The maximum size of the Extra Field 65535 bytes.

       "ExtraFlags => $value"
            Sets the XFL byte in the gzip header to $value.

            If this option is not present, the value stored in XFL  field  will
            be determined by the setting of the "Level" option.

            If "Level => Z_BEST_SPEED" has been specified then XFL is set to 2.
            If "Level => Z_BEST_COMPRESSION" has been specified then XFL is set
            to 4.  Otherwise XFL is set to 0.

       "Strict => 0|1"
            "Strict"  will  optionally  police  the  values supplied with other
            options to ensure they are compliant with RFC1952.

            This option is enabled by default.

            If "Strict" is enabled the following behaviour will be policed:

            •    The value supplied with the "Name" option can only contain ISO
                 8859-1 characters.

            •    The value supplied with the "Comment" option can only  contain
                 ISO 8859-1 characters plus line-feed.

            •    The  values  supplied  with the "-Name" and "-Comment" options
                 cannot contain multiple embedded nulls.

            •    If an "ExtraField" option is specified  and  it  is  a  simple
                 scalar,  it must conform to the sub-field structure as defined
                 in RFC 1952.

            •    If an "ExtraField" option is specified the second byte of  the
                 ID will be checked in each subfield to ensure that it does not
                 contain the reserved value 0x00.

            When "Strict" is disabled the following behaviour will be policed:

            •    The  value  supplied  with  "-Name"  option  can  contain  any
                 character except NULL.

            •    The value supplied with  "-Comment"  option  can  contain  any
                 character except NULL.

            •    The  values  supplied  with the "-Name" and "-Comment" options
                 can contain multiple embedded nulls. The string written to the
                 gzip header will consist of the  characters  up  to,  but  not
                 including, the first embedded NULL.

            •    If  an  "ExtraField"  option  is  specified and it is a simple
                 scalar, the structure will not be checked. The only  error  is
                 if the length is too big.

            •    The  ID header in an "ExtraField" sub-field can consist of any
                 two bytes.

   Examples
       Streaming

       This  very  simple  command  line  example  demonstrates  the  streaming
       capabilities  of  the  module. The code reads data from STDIN or all the
       files given on the commandline, compresses it, and writes the compressed
       data to STDOUT.

           use strict ;
           use warnings ;
           use IO::Compress::Gzip qw(gzip $GzipError) ;

           my $z = IO::Compress::Gzip->new("-", Stream => 1)
               or die "IO::Compress::Gzip failed: $GzipError\n";

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

       Note the use of  "-"  to  means  "STDOUT".  Alternatively  you  can  use
       "\*STDOUT".

       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.gz" there are a few options

       Start by creating the compression object and opening the input file

           use strict ;
           use warnings ;
           use IO::Compress::Gzip qw(gzip $GzipError) ;

           my $input = "file1.txt";
           my $z = IO::Compress::Gzip->new("file1.txt.gz")
               or die "IO::Compress::Gzip failed: $GzipError\n";

           # open the input file
           open my $fh, "<", "file1.txt"
               or die "Cannot open file1.txt: $!\n";

           # loop through the input file & write to the compressed file
           while (<$fh>) {
               $z->print($_);
           }

           # not forgetting to close the compressed file
           $z->close();

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 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::Gzip 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::Gzip
       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 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::Gzip". None are imported by default.

       :all Imports  "gzip",  $GzipError and all symbolic constants that can be
            used by "IO::Compress::Gzip". Same as doing this

                use IO::Compress::Gzip qw(gzip $GzipError :constants) ;

       :constants
            Import all symbolic constants. Same as doing this

                use IO::Compress::Gzip 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

SUPPORT
       General   feedback/questions/bug   reports    should    be    sent    to
       <https://github.com/pmqs/IO-Copress/issues>        (preferred)        or
       <https://rt.cpan.org/Public/Dist/Display.html?Name=IO-Copress>.

SEE ALSO
       Compress::Zlib,      IO::Uncompress::Gunzip,      IO::Compress::Deflate,
       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::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

       For       RFC        1950,        1951        and        1952        see
       <https://datatracker.ietf.org/doc/html/rfc1950>,
       <https://datatracker.ietf.org/doc/html/rfc1951>                      and
       <https://datatracker.ietf.org/doc/html/rfc1952>

       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   the   zlib-ng   compression   library    is
       <https://github.com/zlib-ng/zlib-ng>.

       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) 2005-2024 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 v5.40.1                       2026-08-30            IO::Co...::Gzip(3perl)

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