# `tarfile` --- 读写tar归档文件

源代码: Lib/tarfile.py

The `tarfile` module makes it possible to read and write tar archives, including those using gzip, bz2 and lzma compression. Use the `zipfile` module to read or write `.zip` files, or the higher-level functions in shutil.

Some facts and figures:

- reads and writes `gzip`, `bz2` and `lzma` compressed archives if the respective modules are available.

- 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 all variants of the sparse extension including restoration of sparse files.

- read/write support for the POSIX.1-2001 (pax) format.

- 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.

在 3.3 版更改: Added support for `lzma` compression.

`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:

  模式 | 动作
  --- | ---
  `'r' or 'r:*'` | 打开和读取使用透明压缩（推荐）。
  `'r:'` | 打开和读取不使用压缩。
  `'r:gz'` | 打开和读取使用gzip 压缩。
  `'r:bz2'` | 打开和读取使用bzip2 压缩。
  `'r:xz'` | 打开和读取使用lzma 压缩。
  `'x'` 或 `'x:'` | 创建tarfile不进行压缩。如果文件已经存在，则抛出 `FileExistsError` 异常。
  `'x:gz'` | 使用gzip压缩创建tarfile。如果文件已经存在，则抛出 `FileExistsError` 异常。
  `'x:bz2'` | 使用bzip2 压缩创建tarfile。如果文件已经存在，则抛出 `FileExistsError` 异常。
  `'x:xz'` | 使用lzma 压缩创建tarfile。如果文件已经存在，则抛出 `FileExistsError` 异常。
  `'a' or 'a:'` | 打开以便在没有压缩的情况下追加。如果文件不存在，则创建该文件。
  `'w' or 'w:'` | Open for uncompressed writing.
  `'w:gz'` | Open for gzip compressed writing.
  `'w:bz2'` | Open for bzip2 compressed writing.
  `'w:xz'` | Open for lzma compressed writing.

  Note that `'a:gz'`, `'a:bz2'` or `'a:xz'` 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 in binary mode for name. It is supposed to be at position 0.

  For modes `'w:gz'`, `'r:gz'`, `'w:bz2'`, `'r:bz2'`, `'x:gz'`, `'x:bz2'`, `tarfile.open()` accepts the keyword argument compresslevel (default `9`) to specify the compression level of the file.

  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 random access, see 示例. The currently possible modes:

  模式 | 动作
  --- | ---
  `'r|*'` | 打开 tar 块的 流 以进行透明压缩读取。
  `'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.
  `'r|xz'` | Open an lzma compressed stream for reading.
  `'w|'` | Open an uncompressed stream for writing.
  `'w|gz'` | Open a gzip compressed stream for writing.
  `'w|bz2'` | Open a bzip2 compressed stream for writing.
  `'w|xz'` | Open an lzma compressed stream for writing.

  在 3.5 版更改: 添加了 `'x'` (仅创建) 模式。

  在 3.6 版更改: The name parameter accepts a path-like object.

class `tarfile.``TarFile`

  Class for reading and writing tar archives. Do not use this class directly: 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.

The `tarfile` module defines the following exceptions:

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.

exception `tarfile.``ExtractError`

  Is raised for non-fatal errors when using `TarFile.extract()`, but only if `TarFile.errorlevel``== 2`.

exception `tarfile.``HeaderError`

  Is raised by `TarInfo.frombuf()` if the buffer it gets is invalid.

The following constants are available at the module level:

`tarfile.``ENCODING`

  The default character encoding: `'utf-8'` on Windows, the value returned by `sys.getfilesystemencoding()` otherwise.

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 `PAX_FORMAT`.

  在 3.8 版更改: The default format for new archives was changed to `PAX_FORMAT` from `GNU_FORMAT`.

参见

Module `zipfile`

  Documentation of the `zipfile` standard module.

Archiving operations

  Documentation of the higher-level archiving facilities provided by the standard `shutil` module.

GNU tar manual, Basic Tar Format

  Documentation for tar archive files, including GNU tar extensions.

## 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.

A `TarFile` object can be used as a context manager in a `with` statement. It will automatically be closed when the block is completed. Please note that in the event of an exception an archive opened for writing will not be finalized; only the internally used file object will be closed. See the 示例 section for a use case.

3.2 新版功能: Added support for the context management protocol.

class `tarfile.``TarFile`(name=None, mode='r', fileobj=None, format=DEFAULT_FORMAT, tarinfo=TarInfo, dereference=False, ignore_zeros=False, encoding=ENCODING, errors='surrogateescape', 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. name may be a path-like object. 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, `'w'` to create a new file overwriting an existing one, or `'x'` to create a new file only if it does not already exist.

  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.

  注解

  fileobj is not closed, when `TarFile` is closed.

  format controls the archive format for writing. It must be one of the constants `USTAR_FORMAT`, `GNU_FORMAT` or `PAX_FORMAT` that are defined at module level. When reading, format will be automatically detected, even if different formats are present in a single archive.

  The tarinfo argument can be used to replace the default `TarInfo` class with a different one.

  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` exceptions. If `2`, all non-fatal errors are raised as `TarError` exceptions as well.

  The encoding and errors arguments define the character encoding to be used for reading or writing the archive and how conversion errors are going to be handled. The default settings will work for most users. See section Unicode issues for in-depth information.

  The pax_headers argument is an optional dictionary of strings which will be added as a pax global header if format is `PAX_FORMAT`.

  在 3.2 版更改: Use `'surrogateescape'` as the default for the errors argument.

  在 3.5 版更改: 添加了 `'x'` (仅创建) 模式。

  在 3.6 版更改: The name parameter accepts a path-like object.

classmethod `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.

  注解

  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, *, members=None)

  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. If optional members is given, it must be a subset of the list returned by `getmembers()`.

  在 3.5 版更改: Added the members parameter.

`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.

`TarFile.``extractall`(path=".", members=None, *, numeric_owner=False)

  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.

  If numeric_owner is `True`, the uid and gid numbers from the tarfile are used to set the owner/group for the extracted files. Otherwise, the named values from the tarfile are used.

  警告

  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 `".."`.

  在 3.5 版更改: Added the numeric_owner parameter.

  在 3.6 版更改: The path parameter accepts a path-like object.

`TarFile.``extract`(member, path="", set_attrs=True, *, numeric_owner=False)

  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. path may be a path-like object. File attributes (owner, mtime, mode) are set unless set_attrs is false.

  If numeric_owner is `True`, the uid and gid numbers from the tarfile are used to set the owner/group for the extracted files. Otherwise, the named values from the tarfile are used.

  注解

  The `extract()` method does not take care of several extraction issues. In most cases you should consider using the `extractall()` method.

  警告

  See the warning for `extractall()`.

  在 3.2 版更改: Added the set_attrs parameter.

  在 3.5 版更改: Added the numeric_owner parameter.

  在 3.6 版更改: The path parameter accepts a path-like object.

`TarFile.``extractfile`(member)

  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 or a link, an `io.BufferedReader` object is returned. Otherwise, `None` is returned.

  在 3.3 版更改: Return an `io.BufferedReader` object.

`TarFile.``add`(name, arcname=None, recursive=True, *, filter=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`. Recursion adds entries in sorted order. If filter is given, it should be a function that takes a `TarInfo` object argument and returns the changed `TarInfo` object. If it instead returns `None` the `TarInfo` object will be excluded from the archive. See 示例 for an example.

  在 3.2 版更改: Added the filter parameter.

  在 3.7 版更改: Recursion adds entries in sorted order.

`TarFile.``addfile`(tarinfo, fileobj=None)

  Add the `TarInfo` object tarinfo to the archive. If fileobj is given, it should be a binary file, and `tarinfo.size` bytes are read from it and added to the archive. You can create `TarInfo` objects directly, or by using `gettarinfo()`.

`TarFile.``gettarinfo`(name=None, arcname=None, fileobj=None)

  Create a `TarInfo` object from the result of `os.stat()` or equivalent on an existing file. The file is either named by name, or specified as a file object fileobj with a file descriptor. name may be a path-like object. If given, arcname specifies an alternative name for the file in the archive, otherwise, the name is taken from fileobj’s `name` attribute, or the name argument. The name should be a text string.

  You can modify some of the `TarInfo`’s attributes before you add it using `addfile()`. If the file object is not an ordinary file object positioned at the beginning of the file, attributes such as `size` may need modifying. This is the case for objects such as `GzipFile`. The `name` may also be modified, in which case arcname could be a dummy string.

  在 3.6 版更改: The name parameter accepts a path-like object.

`TarFile.``close`()

  Close the `TarFile`. In write mode, two finishing zero blocks are appended to the archive.

`TarFile.``pax_headers`

  A dictionary containing key-value pairs of pax global headers.

## 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.

classmethod `TarInfo.``frombuf`(buf, encoding, errors)

  Create and return a `TarInfo` object from string buffer buf.

  Raises `HeaderError` if the buffer is invalid.

classmethod `TarInfo.``fromtarfile`(tarfile)

  Read the next member from the `TarFile` object tarfile and return it as a `TarInfo` object.

`TarInfo.``tobuf`(format=DEFAULT_FORMAT, encoding=ENCODING, errors='surrogateescape')

  Create a string buffer from a `TarInfo` object. For information on the arguments see the constructor of the `TarFile` class.

  在 3.2 版更改: Use `'surrogateescape'` as the default for the errors argument.

A `TarInfo` object has the following public data attributes:

`TarInfo.``name`

  Name of the archive member.

`TarInfo.``size`

  Size in bytes.

`TarInfo.``mtime`

  上次修改的时间。

`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.

`TarInfo.``pax_headers`

  A dictionary containing key-value pairs of an associated pax extended header.

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.

## 命令行界面

3.4 新版功能.

The `tarfile` module provides a simple command-line interface to interact with tar archives.

If you want to create a new tar archive, specify its name after the `-c` option and then list the filename(s) that should be included:

    $ python -m tarfile -c monty.tar  spam.txt eggs.txt

Passing a directory is also acceptable:

    $ python -m tarfile -c monty.tar life-of-brian_1979/

If you want to extract a tar archive into the current directory, use the `-e` option:

    $ python -m tarfile -e monty.tar

You can also extract a tar archive into a different directory by passing the directory's name:

    $ python -m tarfile -e monty.tar  other-dir/

For a list of the files in a tar archive, use the `-l` option:

    $ python -m tarfile -l monty.tar

### 命令行选项

`-l``<tarfile>`
`--list``<tarfile>`

  List files in a tarfile.

`-c``<tarfile> <source1> ... <sourceN>`
`--create``<tarfile> <source1> ... <sourceN>`

  Create tarfile from source files.

`-e``<tarfile> [<output_dir>]`
`--extract``<tarfile> [<output_dir>]`

  Extract tarfile into the current directory if output_dir is not specified.

`-t``<tarfile>`
`--test``<tarfile>`

  Test whether the tarfile is valid or not.

`-v````,` `--verbose```

  Verbose output.

## 示例

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()

The same example using the `with` statement:

    import tarfile
    with tarfile.open("sample.tar", "w") as tar:
        for name in ["foo", "bar", "quux"]:
            tar.add(name)

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", end="")
        if tarinfo.isreg():
            print("a regular file.")
        elif tarinfo.isdir():
            print("a directory.")
        else:
            print("something else.")
    tar.close()

How to create an archive and reset the user information using the filter parameter in `TarFile.add()`:

    import tarfile
    def reset(tarinfo):
        tarinfo.uid = tarinfo.gid = 0
        tarinfo.uname = tarinfo.gname = "root"
        return tarinfo
    tar = tarfile.open("sample.tar.gz", "w:gz")
    tar.add("foo", filter=reset)
    tar.close()

## Supported tar formats

There are three tar formats that can be created with the `tarfile` module:

- The POSIX.1-1988 ustar format (`USTAR_FORMAT`). It supports filenames up to a length of at best 256 characters and linknames up to 100 characters. The maximum file size is 8 GiB. This is an old and limited but widely supported format.

- The GNU tar format (`GNU_FORMAT`). It supports long filenames and linknames, files bigger than 8 GiB and sparse files. It is the de facto standard on GNU/Linux systems. `tarfile` fully supports the GNU tar extensions for long names, sparse file support is read-only.

- The POSIX.1-2001 pax format (`PAX_FORMAT`). It is the most flexible format with virtually no limits. It supports long filenames and linknames, large files and stores pathnames in a portable way. Modern tar implementations, including GNU tar, bsdtar/libarchive and star, fully support extended pax features; some old or unmaintained libraries may not, but should treat pax archives as if they were in the universally-supported ustar format. It is the current default format for new archives.

  It extends the existing ustar format with extra headers for information that cannot be stored otherwise. There are two flavours of pax headers: Extended headers only affect the subsequent file header, global headers are valid for the complete archive and affect all following files. All the data in a pax header is encoded in UTF-8 for portability reasons.

There are some more variants of the tar format which can be read, but not created:

- The ancient V7 format. This is the first tar format from Unix Seventh Edition, storing only regular files and directories. Names must not be longer than 100 characters, there is no user/group name information. Some archives have miscalculated header checksums in case of fields with non-ASCII characters.

- The SunOS tar extended format. This format is a variant of the POSIX.1-2001 pax format, but is not compatible.

## 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 (which is the basis of all other formats) 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. Textual metadata (like filenames, linknames, user/group names) 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 metadata using the universal character encoding UTF-8.

The details of character conversion in `tarfile` are controlled by the encoding and errors keyword arguments of the `TarFile` class.

encoding defines the character encoding to use for the metadata in the archive. The default value is `sys.getfilesystemencoding()` or `'ascii'` as a fallback. Depending on whether the archive is read or written, the metadata must be either decoded or encoded. If encoding is not set appropriately, this conversion may fail.

The errors argument defines how characters are treated that cannot be converted. Possible values are listed in section 错误处理方案. The default scheme is `'surrogateescape'` which Python also uses for its file system calls, see 文件名，命令行参数，以及环境变量。.

For `PAX_FORMAT` archives (the default), encoding is generally not needed because all the metadata is stored using UTF-8. encoding is only used in the rare cases when binary pax headers are decoded or when strings with surrogate characters are stored.