tarfile — Read and write tar archive files
New in version 2.3.
The tarfile module makes it possible to read and write tar
archives, including those using gzip or bz2 compression.
(.zip files can be read and written using the zipfile module.)
Some facts and figures:
reads and writes gzip and bz2 compressed archives.
read/write support for the POSIX.1-1988 (ustar) format.
read/write support for the GNU tar format including longname and longlink
extensions, read-only support for the sparse extension.
read/write support for the POSIX.1-2001 (pax) format.
New in version 2.6.
handles directories, regular files, hardlinks, symbolic links, fifos,
character devices and block devices and is able to acquire and restore file
information like timestamp, access permissions and owner.
-
tarfile.open(name=None, mode='r', fileobj=None, bufsize=10240, **kwargs)
Return a TarFile object for the pathname name. For detailed
information on TarFile objects and the keyword arguments that are
allowed, see TarFile Objects.
mode has to be a string of the form 'filemode[:compression]', it defaults
to 'r'. Here is a full list of mode combinations:
| mode |
action |
|---|
| 'r' or 'r:*' |
Open for reading with transparent
compression (recommended). |
| 'r:' |
Open for reading exclusively without
compression. |
| 'r:gz' |
Open for reading with gzip compression. |
| 'r:bz2' |
Open for reading with bzip2 compression. |
| 'a' or 'a:' |
Open for appending with no compression. The
file is created if it does not exist. |
| 'w' or 'w:' |
Open for uncompressed writing. |
| 'w:gz' |
Open for gzip compressed writing. |
| 'w:bz2' |
Open for bzip2 compressed writing. |
Note that 'a:gz' or 'a:bz2' is not possible. If mode is not suitable
to open a certain (compressed) file for reading, ReadError is raised. Use
mode 'r' to avoid this. If a compression method is not supported,
CompressionError is raised.
If fileobj is specified, it is used as an alternative to a file object opened
for name. It is supposed to be at position 0.
For special purposes, there is a second format for mode:
'filemode|[compression]'. tarfile.open() will return a TarFile
object that processes its data as a stream of blocks. No random seeking will
be done on the file. If given, fileobj may be any object that has a
read() or write() method (depending on the mode). bufsize
specifies the blocksize and defaults to 20 * 512 bytes. Use this variant
in combination with e.g. sys.stdin, a socket file object or a tape
device. However, such a TarFile object is limited in that it does
not allow to be accessed randomly, see Examples. The currently
possible modes:
| Mode |
Action |
|---|
| 'r|*' |
Open a stream of tar blocks for reading
with transparent compression. |
| 'r|' |
Open a stream of uncompressed tar blocks
for reading. |
| 'r|gz' |
Open a gzip compressed stream for
reading. |
| 'r|bz2' |
Open a bzip2 compressed stream for
reading. |
| 'w|' |
Open an uncompressed stream for writing. |
| 'w|gz' |
Open an gzip compressed stream for
writing. |
| 'w|bz2' |
Open an bzip2 compressed stream for
writing. |
-
class tarfile.TarFile
- Class for reading and writing tar archives. Do not use this class directly,
better use tarfile.open() instead. See TarFile Objects.
-
tarfile.is_tarfile(name)
- Return True if name is a tar archive file, that the tarfile
module can read.
-
class tarfile.TarFileCompat(filename, mode='r', compression=TAR_PLAIN)
Class for limited access to tar archives with a zipfile-like interface.
Please consult the documentation of the zipfile module for more details.
compression must be one of the following constants:
-
TAR_PLAIN
- Constant for an uncompressed tar archive.
-
TAR_GZIPPED
- Constant for a gzip compressed tar archive.
Deprecated since version 2.6: The TarFileCompat class has been deprecated for removal in Python 3.0.
-
exception tarfile.TarError
- Base class for all tarfile exceptions.
-
exception tarfile.ReadError
- Is raised when a tar archive is opened, that either cannot be handled by the
tarfile module or is somehow invalid.
-
exception tarfile.CompressionError
- Is raised when a compression method is not supported or when the data cannot be
decoded properly.
-
exception tarfile.StreamError
- Is raised for the limitations that are typical for stream-like TarFile
objects.
- Is raised for non-fatal errors when using TarFile.extract(), but only if
TarFile.errorlevel== 2.
Is raised by TarInfo.frombuf() if the buffer it gets is invalid.
New in version 2.6.
Each of the following constants defines a tar archive format that the
tarfile module is able to create. See section Supported tar formats for
details.
-
tarfile.USTAR_FORMAT
- POSIX.1-1988 (ustar) format.
-
tarfile.GNU_FORMAT
- GNU tar format.
-
tarfile.PAX_FORMAT
- POSIX.1-2001 (pax) format.
-
tarfile.DEFAULT_FORMAT
- The default format for creating archives. This is currently GNU_FORMAT.
The following variables are available on module level:
-
tarfile.ENCODING
- The default character encoding i.e. the value from either
sys.getfilesystemencoding() or sys.getdefaultencoding().
TarFile Objects
The TarFile object provides an interface to a tar archive. A tar
archive is a sequence of blocks. An archive member (a stored file) is made up of
a header block followed by data blocks. It is possible to store a file in a tar
archive several times. Each archive member is represented by a TarInfo
object, see TarInfo Objects for details.
-
class tarfile.TarFile(name=None, mode='r', fileobj=None, format=DEFAULT_FORMAT, tarinfo=TarInfo, dereference=False, ignore_zeros=False, encoding=ENCODING, errors=None, pax_headers=None, debug=0, errorlevel=0)
All following arguments are optional and can be accessed as instance attributes
as well.
name is the pathname of the archive. It can be omitted if fileobj is given.
In this case, the file object’s name attribute is used if it exists.
mode is either 'r' to read from an existing archive, 'a' to append
data to an existing file or 'w' to create a new file overwriting an existing
one.
If fileobj is given, it is used for reading or writing data. If it can be
determined, mode is overridden by fileobj‘s mode. fileobj will be used
from position 0.
Note
fileobj is not closed, when TarFile is closed.
format controls the archive format. It must be one of the constants
USTAR_FORMAT, GNU_FORMAT or PAX_FORMAT that are
defined at module level.
New in version 2.6.
The tarinfo argument can be used to replace the default TarInfo class
with a different one.
New in version 2.6.
If dereference is False, add symbolic and hard links to the archive. If it
is True, add the content of the target files to the archive. This has no
effect on systems that do not support symbolic links.
If ignore_zeros is False, treat an empty block as the end of the archive.
If it is True, skip empty (and invalid) blocks and try to get as many members
as possible. This is only useful for reading concatenated or damaged archives.
debug can be set from 0 (no debug messages) up to 3 (all debug
messages). The messages are written to sys.stderr.
If errorlevel is 0, all errors are ignored when using TarFile.extract().
Nevertheless, they appear as error messages in the debug output, when debugging
is enabled. If 1, all fatal errors are raised as OSError or
IOError exceptions. If 2, all non-fatal errors are raised as
TarError exceptions as well.
The encoding and errors arguments control the way strings are converted to
unicode objects and vice versa. The default settings will work for most users.
See section Unicode issues for in-depth information.
New in version 2.6.
The pax_headers argument is an optional dictionary of unicode strings which
will be added as a pax global header if format is PAX_FORMAT.
New in version 2.6.
-
TarFile.open(...)
- Alternative constructor. The tarfile.open() function is actually a
shortcut to this classmethod.
-
TarFile.getmember(name)
Return a TarInfo object for member name. If name can not be found
in the archive, KeyError is raised.
Note
If a member occurs more than once in the archive, its last occurrence is assumed
to be the most up-to-date version.
-
TarFile.getmembers()
- Return the members of the archive as a list of TarInfo objects. The
list has the same order as the members in the archive.
-
TarFile.getnames()
- Return the members as a list of their names. It has the same order as the list
returned by getmembers().
-
TarFile.list(verbose=True)
- Print a table of contents to sys.stdout. If verbose is False,
only the names of the members are printed. If it is True, output
similar to that of ls -l is produced.
-
TarFile.next()
- Return the next member of the archive as a TarInfo object, when
TarFile is opened for reading. Return None if there is no more
available.
Extract all members from the archive to the current working directory or
directory path. If optional members is given, it must be a subset of the
list returned by getmembers(). Directory information like owner,
modification time and permissions are set after all members have been extracted.
This is done to work around two problems: A directory’s modification time is
reset each time a file is created in it. And, if a directory’s permissions do
not allow writing, extracting files to it will fail.
Warning
Never extract archives from untrusted sources without prior inspection.
It is possible that files are created outside of path, e.g. members
that have absolute filenames starting with "/" or filenames with two
dots "..".
New in version 2.5.
Extract a member from the archive to the current working directory, using its
full name. Its file information is extracted as accurately as possible. member
may be a filename or a TarInfo object. You can specify a different
directory using path.
Note
The extract() method does not take care of several extraction issues.
In most cases you should consider using the extractall() method.
Extract a member from the archive as a file object. member may be a filename
or a TarInfo object. If member is a regular file, a file-like object
is returned. If member is a link, a file-like object is constructed from the
link’s target. If member is none of the above, None is returned.
Note
The file-like object is read-only and provides the following methods:
read(), readline(), readlines(), seek(), tell().
-
TarFile.add(name, arcname=None, recursive=True, exclude=None)
Add the file name to the archive. name may be any type of file (directory,
fifo, symbolic link, etc.). If given, arcname specifies an alternative name
for the file in the archive. Directories are added recursively by default. This
can be avoided by setting recursive to False. If exclude is given
it must be a function that takes one filename argument and returns a boolean
value. Depending on this value the respective file is either excluded
(True) or added (False).
Changed in version 2.6: Added the exclude parameter.
-
TarFile.addfile(tarinfo, fileobj=None)
Add the TarInfo object tarinfo to the archive. If fileobj is given,
tarinfo.size bytes are read from it and added to the archive. You can
create TarInfo objects using gettarinfo().
Note
On Windows platforms, fileobj should always be opened with mode 'rb' to
avoid irritation about the file size.
-
TarFile.gettarinfo(name=None, arcname=None, fileobj=None)
- Create a TarInfo object for either the file name or the file object
fileobj (using os.fstat() on its file descriptor). You can modify some
of the TarInfo‘s attributes before you add it using addfile().
If given, arcname specifies an alternative name for the file in the archive.
-
TarFile.close()
- Close the TarFile. In write mode, two finishing zero blocks are
appended to the archive.
-
TarFile.posix
Setting this to True is equivalent to setting the format
attribute to USTAR_FORMAT, False is equivalent to
GNU_FORMAT.
Changed in version 2.4: posix defaults to False.
Deprecated since version 2.6: Use the format attribute instead.
A dictionary containing key-value pairs of pax global headers.
New in version 2.6.
TarInfo Objects
A TarInfo object represents one member in a TarFile. Aside
from storing all required attributes of a file (like file type, size, time,
permissions, owner etc.), it provides some useful methods to determine its type.
It does not contain the file’s data itself.
TarInfo objects are returned by TarFile‘s methods
getmember(), getmembers() and gettarinfo().
-
class tarfile.TarInfo(name="")
- Create a TarInfo object.
-
TarInfo.frombuf(buf)
Create and return a TarInfo object from string buffer buf.
New in version 2.6: Raises HeaderError if the buffer is invalid..
-
TarInfo.fromtarfile(tarfile)
Read the next member from the TarFile object tarfile and return it as
a TarInfo object.
New in version 2.6.
-
TarInfo.tobuf(format=DEFAULT_FORMAT, encoding=ENCODING, errors='strict')
Create a string buffer from a TarInfo object. For information on the
arguments see the constructor of the TarFile class.
Changed in version 2.6: The arguments were added.
A TarInfo object has the following public data attributes:
-
TarInfo.name
- Name of the archive member.
-
TarInfo.size
- Size in bytes.
-
TarInfo.mtime
- Time of last modification.
-
TarInfo.mode
- Permission bits.
-
TarInfo.type
- File type. type is usually one of these constants: REGTYPE,
AREGTYPE, LNKTYPE, SYMTYPE, DIRTYPE,
FIFOTYPE, CONTTYPE, CHRTYPE, BLKTYPE,
GNUTYPE_SPARSE. To determine the type of a TarInfo object
more conveniently, use the is_*() methods below.
-
TarInfo.linkname
- Name of the target file name, which is only present in TarInfo objects
of type LNKTYPE and SYMTYPE.
-
TarInfo.uid
- User ID of the user who originally stored this member.
-
TarInfo.gid
- Group ID of the user who originally stored this member.
-
TarInfo.uname
- User name.
-
TarInfo.gname
- Group name.
A dictionary containing key-value pairs of an associated pax extended header.
New in version 2.6.
A TarInfo object also provides some convenient query methods:
-
TarInfo.isfile()
- Return True if the Tarinfo object is a regular file.
-
TarInfo.isreg()
- Same as isfile().
-
TarInfo.isdir()
- Return True if it is a directory.
-
TarInfo.issym()
- Return True if it is a symbolic link.
-
TarInfo.islnk()
- Return True if it is a hard link.
-
TarInfo.ischr()
- Return True if it is a character device.
-
TarInfo.isblk()
- Return True if it is a block device.
-
TarInfo.isfifo()
- Return True if it is a FIFO.
-
TarInfo.isdev()
- Return True if it is one of character device, block device or FIFO.
Examples
How to extract an entire tar archive to the current working directory:
import tarfile
tar = tarfile.open("sample.tar.gz")
tar.extractall()
tar.close()
How to extract a subset of a tar archive with TarFile.extractall() using
a generator function instead of a list:
import os
import tarfile
def py_files(members):
for tarinfo in members:
if os.path.splitext(tarinfo.name)[1] == ".py":
yield tarinfo
tar = tarfile.open("sample.tar.gz")
tar.extractall(members=py_files(tar))
tar.close()
How to create an uncompressed tar archive from a list of filenames:
import tarfile
tar = tarfile.open("sample.tar", "w")
for name in ["foo", "bar", "quux"]:
tar.add(name)
tar.close()
How to read a gzip compressed tar archive and display some member information:
import tarfile
tar = tarfile.open("sample.tar.gz", "r:gz")
for tarinfo in tar:
print tarinfo.name, "is", tarinfo.size, "bytes in size and is",
if tarinfo.isreg():
print "a regular file."
elif tarinfo.isdir():
print "a directory."
else:
print "something else."
tar.close()
Unicode issues
The tar format was originally conceived to make backups on tape drives with the
main focus on preserving file system information. Nowadays tar archives are
commonly used for file distribution and exchanging archives over networks. One
problem of the original format (that all other formats are merely variants of)
is that there is no concept of supporting different character encodings. For
example, an ordinary tar archive created on a UTF-8 system cannot be read
correctly on a Latin-1 system if it contains non-ASCII characters. Names (i.e.
filenames, linknames, user/group names) containing these characters will appear
damaged. Unfortunately, there is no way to autodetect the encoding of an
archive.
The pax format was designed to solve this problem. It stores non-ASCII names
using the universal character encoding UTF-8. When a pax archive is read,
these UTF-8 names are converted to the encoding of the local file system.
The details of unicode conversion are controlled by the encoding and errors
keyword arguments of the TarFile class.
The default value for encoding is the local character encoding. It is deduced
from sys.getfilesystemencoding() and sys.getdefaultencoding(). In
read mode, encoding is used exclusively to convert unicode names from a pax
archive to strings in the local character encoding. In write mode, the use of
encoding depends on the chosen archive format. In case of PAX_FORMAT,
input names that contain non-ASCII characters need to be decoded before being
stored as UTF-8 strings. The other formats do not make use of encoding
unless unicode objects are used as input names. These are converted to 8-bit
character strings before they are added to the archive.
The errors argument defines how characters are treated that cannot be
converted to or from encoding. Possible values are listed in section
Codec Base Classes. In read mode, there is an additional scheme
'utf-8' which means that bad characters are replaced by their UTF-8
representation. This is the default scheme. In write mode the default value for
errors is 'strict' to ensure that name information is not altered
unnoticed.
|
