Source code:
———
This module provides a simple interface to compress and decompress files just like the GNU programs gzip and gunzip would.
This is an
. If it is missing from your copy of CPython, look for documentation from your distributor (that is, whoever provided Python to you). If you are the distributor, see
Requirements for optional modules
.
The data compression is provided by the
module.
The gzip module provides the
class, as well as the
,
and
convenience functions. The GzipFile class reads and writes gzip-format files, automatically compressing or decompressing the data so that it looks like an ordinary
.
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.
The module defines the following items:
gzip.open(filename, mode='rb', compresslevel=9, encoding=None, errors=None, newline=None)
Open a gzip-compressed file in binary or text mode, returning a
.
The filename argument can be an actual filename (a
or
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
constructor.
For binary mode, this function is equivalent to the
constructor: GzipFile(filename,mode,compresslevel). In this case, the encoding, errors and newline arguments must not be provided.
For text mode, a
object is created, and wrapped in an
instance with the specified encoding, error handling behavior, and line ending(s).
Changed in version 3.3: Added support for filename being a file object, support for text mode, and the encoding, errors and newline arguments.
Changed in version 3.4: Added support for the 'x', 'xb' and 'xt' modes.
exceptiongzip.BadGzipFile
An exception raised for invalid gzip files. It inherits from
.
and
can also be raised for invalid gzip files.
Added in version 3.8.
classgzip.GzipFile(filename=None, mode=None, compresslevel=9, fileobj=None, mtime=None)
Constructor for the GzipFile class, which simulates most of the methods of a
, with the exception of the
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
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'. In future Python releases the mode of fileobj will not be used. It is better to always specify mode for writing.
Note that the file is always opened in binary mode. To open a compressed file in text mode, use
(or wrap your GzipFile with an
).
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 optional mtime argument is the timestamp requested by gzip. The time is in Unix format, i.e., seconds since 00:00:00 UTC, January 1, 1970. If mtime is omitted or None, the current time is used. Use mtime = 0 to generate a compressed stream that does not depend on creation time.
See below for the
attribute that is set when decompressing.
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
object opened for writing as fileobj, and retrieve the resulting memory buffer using the io.BytesIO object’s
method.
GzipFile supports the
interface, including iteration and the
statement. Only the
method isn’t implemented.
GzipFile also provides the following method and attribute:
peek(n)
Read n uncompressed bytes without advancing the file position. The number of bytes returned may be more or less than requested.
Note
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).
Added in version 3.2.
mode
'rb' for reading and 'wb' for writing.
Changed in version 3.13: In previous versions it was an integer 1 or 2.
mtime
When decompressing, this attribute is set to the last timestamp in the most recently read header. It is an integer, holding the number of seconds since the Unix epoch (00:00:00 UTC, January 1, 1970). The initial value before reading any headers is None.
name
The path to the gzip file on disk, as a
or
. Equivalent to the output of
on the original input path, with no other normalization, resolution or expansion.
Changed in version 3.1: Support for the
statement was added, along with the mtime constructor argument and
attribute.
Changed in version 3.2: Support for zero-padded and unseekable files was added.
Changed in version 3.4: Added support for the 'x' and 'xb' modes.
Changed in version 3.5: Added support for writing arbitrary
. The
method now accepts an argument of None.
Deprecated since version 3.9: Opening GzipFile for writing without specifying the mode argument is deprecated.
Changed in version 3.12: Remove the filename attribute, use the
attribute instead.
gzip.compress(data, compresslevel=9, *, mtime=0)
Compress the data, returning a
object containing the compressed data. compresslevel and mtime have the same meaning as in the
constructor above, but mtime defaults to 0 for reproducible output.
Added in version 3.2.
Changed in version 3.8: Added the mtime parameter for reproducible output.
Changed in version 3.11: Speed is improved by compressing all data at once instead of in a streamed fashion. Calls with mtime set to 0 are delegated to
for better speed. In this situation the output may contain a gzip header “OS” byte value other than 255 “unknown” as supplied by the underlying zlib implementation.
Changed in version 3.13: The gzip header OS byte is guaranteed to be set to 255 when this function is used as was the case in 3.10 and earlier.
Changed in version 3.14: The mtime parameter now defaults to 0 for reproducible output. For the previous behaviour of using the current time, pass None to mtime.
gzip.decompress(data)
Decompress the data, returning a
object containing the uncompressed data. This function is capable of decompressing multi-member gzip data (multiple gzip blocks concatenated together). When the data is certain to contain only one member the
function with wbits set to 31 is faster.
Added in version 3.2.
Changed in version 3.11: Speed is improved by decompressing members at once in memory instead of in a streamed fashion.
Examples of usage
Example of how to read a compressed file:
importgzipwithgzip.open('/home/joe/file.txt.gz','rb')asf:file_content=f.read()Example of how to create a compressed GZIP file:
importgzipcontent=b"Lots of content here"withgzip.open('/home/joe/file.txt.gz','wb')asf:f.write(content)Example of how to GZIP compress an existing file:
importgzipimportshutilwithopen('/home/joe/file.txt','rb')asf_in:withgzip.open('/home/joe/file.txt.gz','wb')asf_out:shutil.copyfileobj(f_in,f_out)Example of how to GZIP compress a binary string:
importgzips_in=b"Lots of content here"s_out=gzip.compress(s_in)See also
Module
The basic data compression module needed to support the gzip file format.
In case gzip (de)compression is a bottleneck, the
package speeds up (de)compression with a mostly compatible API.
Command-line interface
The gzip module provides a simple command line interface to compress or decompress files.
Once executed the gzip module keeps the input file(s).
Changed in version 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.
Command-line options
file
If file is not specified, read from
.
--fast
Indicates the fastest compression method (less compression).
--best
Indicates the slowest compression method (best compression).
-d,--decompress
Decompress the given file.
-h,--help
Show the help message.