"gzip" --- Support for **gzip** files
*************************************

**Código-fonte:** Lib/gzip.py

======================================================================

Esse módulo disponibiliza uma interface simples para comprimir e
extrair arquivos como os programas GNU **gzip** e **gunzip** fazem.

A compressão de dados é realizada pelo módulo "zlib".

The "gzip" module provides the "GzipFile" class, as well as the
"open()", "compress()" and "decompress()" convenience functions. The
"GzipFile" class reads and writes **gzip**-format files, automatically
compressing or decompressing the data so that it looks like an
ordinary *file object*.

Note that additional file formats which can be decompressed by the
**gzip** and **gunzip** programs, such  as those produced by
**compress** and **pack**, are not supported by this module.

Este módulo define os seguintes itens:

gzip.open(filename, mode='rb', compresslevel=9, encoding=None, errors=None, newline=None)

   Abre um arquivo comprimido com gzip em modo binário ou texto,
   retornando *file object*.

   The *filename* argument can be an actual filename (a "str" or
   "bytes" object), or an existing file object to read from or write
   to.

   The *mode* argument can be any of "'r'", "'rb'", "'a'", "'ab'",
   "'w'", "'wb'", "'x'" or "'xb'" for binary mode, or "'rt'", "'at'",
   "'wt'", or "'xt'" for text mode. The default is "'rb'".

   The *compresslevel* argument is an integer from 0 to 9, as for the
   "GzipFile" constructor.

   For binary mode, this function is equivalent to the "GzipFile"
   constructor: "GzipFile(filename, mode, compresslevel)". In this
   case, the *encoding*, *errors* and *newline* arguments must not be
   provided.

   For text mode, a "GzipFile" object is created, and wrapped in an
   "io.TextIOWrapper" instance with the specified encoding, error
   handling behavior, and line ending(s).

   Alterado na versão 3.3: Added support for *filename* being a file
   object, support for text mode, and the *encoding*, *errors* and
   *newline* arguments.

   Alterado na versão 3.4: Adicionado suporte para os modos "'x'",
   "'xb'" e "'xt'".

   Alterado na versão 3.6: Aceita um *objeto caminho ou similar*.

exception gzip.BadGzipFile

   An exception raised for invalid gzip files.  It inherits "OSError".
   "EOFError" and "zlib.error" can also be raised for invalid gzip
   files.

   Novo na versão 3.8.

class gzip.GzipFile(filename=None, mode=None, compresslevel=9, fileobj=None, mtime=None)

   Constructor for the "GzipFile" class, which simulates most of the
   methods of a *file object*, with the exception of the "truncate()"
   method.  At least one of *fileobj* and *filename* must be given a
   non-trivial value.

   The new class instance is based on *fileobj*, which can be a
   regular file, an "io.BytesIO" object, or any other object which
   simulates a file.  It defaults to "None", in which case *filename*
   is opened to provide a file object.

   When *fileobj* is not "None", the *filename* argument is only used
   to be included in the **gzip** file header, which may include the
   original filename of the uncompressed file.  It defaults to the
   filename of *fileobj*, if discernible; otherwise, it defaults to
   the empty string, and in this case the original filename is not
   included in the header.

   The *mode* argument can be any of "'r'", "'rb'", "'a'", "'ab'",
   "'w'", "'wb'", "'x'", or "'xb'", depending on whether the file will
   be read or written.  The default is the mode of *fileobj* if
   discernible; otherwise, the default is "'rb'".

   Note that the file is always opened in binary mode. To open a
   compressed file in text mode, use "open()" (or wrap your "GzipFile"
   with an "io.TextIOWrapper").

   The *compresslevel* argument is an integer from "0" to "9"
   controlling the level of compression; "1" is fastest and produces
   the least compression, and "9" is slowest and produces the most
   compression. "0" is no compression. The default is "9".

   The *mtime* argument is an optional numeric timestamp to be written
   to the last modification time field in the stream when compressing.
   It should only be provided in compression mode.  If omitted or
   "None", the current time is used.  See the "mtime" attribute for
   more details.

   Calling a "GzipFile" object's "close()" method does not close
   *fileobj*, since you might wish to append more material after the
   compressed data.  This also allows you to pass an "io.BytesIO"
   object opened for writing as *fileobj*, and retrieve the resulting
   memory buffer using the "io.BytesIO" object's "getvalue()" method.

   "GzipFile" supports the "io.BufferedIOBase" interface, including
   iteration and the "with" statement.  Only the "truncate()" method
   isn't implemented.

   "GzipFile" também disponibiliza os seguintes métodos e atributos:

   peek(n)

      Read *n* uncompressed bytes without advancing the file position.
      At most one single read on the compressed stream is done to
      satisfy the call.  The number of bytes returned may be more or
      less than requested.

      Nota:

        While calling "peek()" does not change the file position of
        the "GzipFile", it may change the position of the underlying
        file object (e.g. if the "GzipFile" was constructed with the
        *fileobj* parameter).

      Novo na versão 3.2.

   mtime

      When decompressing, the value of the last modification time
      field in the most recently read header may be read from this
      attribute, as an integer.  The initial value before reading any
      headers is "None".

      All **gzip** compressed streams are required to contain this
      timestamp field.  Some programs, such as **gunzip**, make use of
      the timestamp.  The format is the same as the return value of
      "time.time()" and the "st_mtime" attribute of the object
      returned by "os.stat()".

   Alterado na versão 3.1: Support for the "with" statement was added,
   along with the *mtime* constructor argument and "mtime" attribute.

   Alterado na versão 3.2: Support for zero-padded and unseekable
   files was added.

   Alterado na versão 3.3: O método "io.BufferedIOBase.read1()" foi
   implementado agora.

   Alterado na versão 3.4: Added support for the "'x'" and "'xb'"
   modes.

   Alterado na versão 3.5: Added support for writing arbitrary *bytes-
   like objects*. The "read()" method now accepts an argument of
   "None".

   Alterado na versão 3.6: Aceita um *objeto caminho ou similar*.

gzip.compress(data, compresslevel=9, *, mtime=None)

   Compress the *data*, returning a "bytes" object containing the
   compressed data.  *compresslevel* and *mtime* have the same meaning
   as in the "GzipFile" constructor above.

   Novo na versão 3.2.

   Alterado na versão 3.8: Added the *mtime* parameter for
   reproducible output.

gzip.decompress(data)

   Decompress the *data*, returning a "bytes" object containing the
   uncompressed data.

   Novo na versão 3.2.


Exemplos de uso
===============

Exemplo de como ler um arquivo comprimido:

   import gzip
   with gzip.open('/home/joe/file.txt.gz', 'rb') as f:
       file_content = f.read()

Exemplo de como criar um arquivo comprimido com GZIP:

   import gzip
   content = b"Lots of content here"
   with gzip.open('/home/joe/file.txt.gz', 'wb') as f:
       f.write(content)

Exemplo de como comprimir um arquivo existente com GZIP:

   import gzip
   import shutil
   with open('/home/joe/file.txt', 'rb') as f_in:
       with gzip.open('/home/joe/file.txt.gz', 'wb') as f_out:
           shutil.copyfileobj(f_in, f_out)

Exemplo de como comprimir uma string binária com compressão GZIP:

   import gzip
   s_in = b"Lots of content here"
   s_out = gzip.compress(s_in)

Ver também:

  Módulo "zlib"
     The basic data compression module needed to support the **gzip**
     file format.


Interface de linha de comando
=============================

The "gzip" module provides a simple command line interface to compress
or decompress files.

Once executed the "gzip" module keeps the input file(s).

Alterado na versão 3.8: Add a new command line interface with a usage.
By default, when you will execute the CLI, the default compression
level is 6.


Opções da linha de comando
--------------------------

file

   If *file* is not specified, read from "sys.stdin".

--fast

   Indica o método mais rápido de compressão (menor compressão)

--best

   Indica o método mais lento de compressão (melhor compressão).

-d, --decompress

   Descompacta o arquivo dado.

-h, --help

   Exibe a mensagem de ajuda.
