# `shutil` — 高階檔案操作

原始碼：Lib/shutil.py

The `shutil` module offers a number of high-level operations on files and collections of files. In particular, functions are provided which support file copying and removal. For operations on individual files, see also the `os` module.

警告

Even the higher-level file copying functions (`shutil.copy()`, `shutil.copy2()`) cannot copy all file metadata.

On POSIX platforms, this means that file owner and group are lost as well as ACLs. On Mac OS, the resource fork and other metadata are not used. This means that resources will be lost and file type and creator codes will not be correct. On Windows, file owners, ACLs and alternate data streams are not copied.

## Directory and files operations

shutil.copyfileobj(fsrc, fdst[, length])

  Copy the contents of the file-like object fsrc to the file-like object fdst. The integer length, if given, is the buffer size. In particular, a negative length value means to copy the data without looping over the source data in chunks; by default the data is read in chunks to avoid uncontrolled memory consumption. Note that if the current file position of the fsrc object is not 0, only the contents from the current file position to the end of the file will be copied.

shutil.copyfile(src, dst, *, follow_symlinks=True)

  Copy the contents (no metadata) of the file named src to a file named dst and return dst in the most efficient way possible. src and dst are path-like objects or path names given as strings.

  dst must be the complete target file name; look at `copy()` for a copy that accepts a target directory path. If src and dst specify the same file, `SameFileError` is raised.

  The destination location must be writable; otherwise, an `OSError` exception will be raised. If dst already exists, it will be replaced. Special files such as character or block devices and pipes cannot be copied with this function.

  If follow_symlinks is false and src is a symbolic link, a new symbolic link will be created instead of copying the file src points to.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copyfile`。

  在 3.3 版的變更: `IOError` used to be raised instead of `OSError`. Added follow_symlinks argument. Now returns dst.

  在 3.4 版的變更: Raise `SameFileError` instead of `Error`. Since the former is a subclass of the latter, this change is backward compatible.

  在 3.8 版的變更: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.

exception shutil.SameFileError

  This exception is raised if source and destination in `copyfile()` are the same file.

  在 3.4 版被加入.

shutil.copymode(src, dst, *, follow_symlinks=True)

  Copy the permission bits from src to dst. The file contents, owner, and group are unaffected. src and dst are path-like objects or path names given as strings. If follow_symlinks is false, and both src and dst are symbolic links, `copymode()` will attempt to modify the mode of dst itself (rather than the file it points to). This functionality is not available on every platform; please see `copystat()` for more information. If `copymode()` cannot modify symbolic links on the local platform, and it is asked to do so, it will do nothing and return.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copymode`。

  在 3.3 版的變更: 新增 follow_symlinks 引數。

shutil.copystat(src, dst, *, follow_symlinks=True)

  Copy the permission bits, last access time, last modification time, and flags from src to dst. On Linux, `copystat()` also copies the "extended attributes" where possible. The file contents, owner, and group are unaffected. src and dst are path-like objects or path names given as strings.

  If follow_symlinks is false, and src and dst both refer to symbolic links, `copystat()` will operate on the symbolic links themselves rather than the files the symbolic links refer to—reading the information from the src symbolic link, and writing the information to the dst symbolic link.

  備註

  Not all platforms provide the ability to examine and modify symbolic links. Python itself can tell you what functionality is locally available.

  - If `os.chmod in os.supports_follow_symlinks` is `True`, `copystat()` can modify the permission bits of a symbolic link.

  - If `os.utime in os.supports_follow_symlinks` is `True`, `copystat()` can modify the last access and modification times of a symbolic link.

  - If `os.chflags in os.supports_follow_symlinks` is `True`, `copystat()` can modify the flags of a symbolic link. (`os.chflags` is not available on all platforms.)

  On platforms where some or all of this functionality is unavailable, when asked to modify a symbolic link, `copystat()` will copy everything it can. `copystat()` never returns failure.

  更多資訊請見 `os.supports_follow_symlinks`。

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copystat`。

  在 3.3 版的變更: Added follow_symlinks argument and support for Linux extended attributes.

shutil.copy(src, dst, *, follow_symlinks=True)

  Copies the file src to the file or directory dst. src and dst should be path-like objects or strings. If dst specifies a directory, the file will be copied into dst using the base filename from src. If dst specifies a file that already exists, it will be replaced. Returns the path to the newly created file.

  If follow_symlinks is false, and src is a symbolic link, dst will be created as a symbolic link. If follow_symlinks is true and src is a symbolic link, dst will be a copy of the file src refers to.

  `copy()` copies the file data and the file's permission mode (see `os.chmod()`). Other metadata, like the file's creation and modification times, is not preserved. To preserve all file metadata from the original, use `copy2()` instead.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copyfile`。

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copymode`。

  在 3.3 版的變更: Added follow_symlinks argument. Now returns path to the newly created file.

  在 3.8 版的變更: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.

shutil.copy2(src, dst, *, follow_symlinks=True)

  Identical to `copy()` except that `copy2()` also attempts to preserve file metadata.

  When follow_symlinks is false, and src is a symbolic link, `copy2()` attempts to copy all metadata from the src symbolic link to the newly created dst symbolic link. However, this functionality is not available on all platforms. On platforms where some or all of this functionality is unavailable, `copy2()` will preserve all the metadata it can; `copy2()` never raises an exception because it cannot preserve file metadata.

  `copy2()` uses `copystat()` to copy the file metadata. Please see `copystat()` for more information about platform support for modifying symbolic link metadata.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copyfile`。

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copystat`。

  在 3.3 版的變更: Added follow_symlinks argument, try to copy extended file system attributes too (currently Linux only). Now returns path to the newly created file.

  在 3.8 版的變更: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.

shutil.ignore_patterns(*patterns)

  This factory function creates a function that can be used as a callable for `copytree()`'s ignore argument, ignoring files and directories that match one of the glob-style patterns provided. See the example below.

shutil.copytree(src, dst, symlinks=False, ignore=None, copy_function=copy2, ignore_dangling_symlinks=False, dirs_exist_ok=False)

  Recursively copy an entire directory tree rooted at src to a directory named dst and return the destination directory. All intermediate directories needed to contain dst will also be created by default.

  Permissions and times of directories are copied with `copystat()`, individual files are copied using `copy2()`.

  If symlinks is true, symbolic links in the source tree are represented as symbolic links in the new tree and the metadata of the original links will be copied as far as the platform allows; if false or omitted, the contents and metadata of the linked files are copied to the new tree.

  When symlinks is false, if the file pointed to by the symlink doesn't exist, an exception will be added in the list of errors raised in an `Error` exception at the end of the copy process. You can set the optional ignore_dangling_symlinks flag to true if you want to silence this exception. Notice that this option has no effect on platforms that don't support `os.symlink()`.

  If ignore is given, it must be a callable that will receive as its arguments the directory being visited by `copytree()`, and a list of its contents, as returned by `os.listdir()`. Since `copytree()` is called recursively, the ignore callable will be called once for each directory that is copied. The callable must return a sequence of directory and file names relative to the current directory (i.e. a subset of the items in its second argument); these names will then be ignored in the copy process. `ignore_patterns()` can be used to create such a callable that ignores names based on glob-style patterns.

  If exception(s) occur, an `Error` is raised with a list of reasons.

  If copy_function is given, it must be a callable that will be used to copy each file. It will be called with the source path and the destination path as arguments. By default, `copy2()` is used, but any function that supports the same signature (like `copy()`) can be used.

  If dirs_exist_ok is false (the default) and dst already exists, a `FileExistsError` is raised. If dirs_exist_ok is true, the copying operation will continue if it encounters existing directories, and files within the dst tree will be overwritten by corresponding files from the src tree.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.copytree`。

  在 3.2 版的變更: Added the copy_function argument to be able to provide a custom copy function. Added the ignore_dangling_symlinks argument to silence dangling symlinks errors when symlinks is false.

  在 3.3 版的變更: Copy metadata when symlinks is false. Now returns dst.

  在 3.8 版的變更: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.

  在 3.8 版的變更: 新增 dirs_exist_ok 參數。

shutil.rmtree(path, ignore_errors=False, onerror=None, *, onexc=None, dir_fd=None)

  Delete an entire directory tree; path must point to a directory (but not a symbolic link to a directory). If ignore_errors is true, errors resulting from failed removals will be ignored; if false or omitted, such errors are handled by calling a handler specified by onexc or onerror or, if both are omitted, exceptions are propagated to the caller.

  This function can support paths relative to directory descriptors.

  備註

  On platforms that support the necessary fd-based functions a symlink attack resistant version of `rmtree()` is used by default. On other platforms, the `rmtree()` implementation is susceptible to a symlink attack: given proper timing and circumstances, attackers can manipulate symlinks on the filesystem to delete files they wouldn't be able to access otherwise. Applications can use the `rmtree.avoids_symlink_attacks` function attribute to determine which case applies.

  If onexc is provided, it must be a callable that accepts three parameters: function, path, and excinfo.

  The first parameter, function, is the function which raised the exception; it depends on the platform and implementation. The second parameter, path, will be the path name passed to function. The third parameter, excinfo, is the exception that was raised. Exceptions raised by onexc will not be caught.

  The deprecated onerror is similar to onexc, except that the third parameter it receives is the tuple returned from `sys.exc_info()`.

  引發一個附帶引數 `path`、`dir_fd` 的稽核事件 `shutil.rmtree`。

  在 3.3 版的變更: Added a symlink attack resistant version that is used automatically if platform supports fd-based functions.

  在 3.8 版的變更: On Windows, will no longer delete the contents of a directory junction before removing the junction.

  在 3.11 版的變更: 新增 dir_fd 參數。

  在 3.12 版的變更: 新增 onexc 參數並棄用 onerror。

  rmtree.avoids_symlink_attacks

    Indicates whether the current platform and implementation provides a symlink attack resistant version of `rmtree()`. Currently this is only true for platforms supporting fd-based directory access functions.

    在 3.3 版被加入.

shutil.move(src, dst, copy_function=copy2)

  Recursively move a file or directory (src) to another location and return the destination.

  If dst is an existing directory or a symlink to a directory, then src is moved inside that directory. The destination path in that directory must not already exist.

  If dst already exists but is not a directory, it may be overwritten depending on `os.rename()` semantics.

  If the destination is on the current filesystem, then `os.rename()` is used. Otherwise, src is copied to the destination using copy_function and then removed. In case of symlinks, a new symlink pointing to the target of src will be created as the destination and src will be removed.

  If copy_function is given, it must be a callable that takes two arguments, src and the destination, and will be used to copy src to the destination if `os.rename()` cannot be used. If the source is a directory, `copytree()` is called, passing it the copy_function. The default copy_function is `copy2()`. Using `copy()` as the copy_function allows the move to succeed when it is not possible to also copy the metadata, at the expense of not copying any of the metadata.

  引發一個附帶引數 `src`、`dst` 的稽核事件 `shutil.move`。

  在 3.3 版的變更: Added explicit symlink handling for foreign filesystems, thus adapting it to the behavior of GNU's mv. Now returns dst.

  在 3.5 版的變更: 新增 copy_function 關鍵字引數。

  在 3.8 版的變更: Platform-specific fast-copy syscalls may be used internally in order to copy the file more efficiently. See Platform-dependent efficient copy operations section.

  在 3.9 版的變更: Accepts a path-like object for both src and dst.

shutil.disk_usage(path)

  Return disk usage statistics about the given path as a named tuple with the attributes total, used and free, which are the amount of total, used and free space, in bytes. path may be a file or a directory.

  備註

  On Unix filesystems, path must point to a path within a mounted filesystem partition. On those platforms, CPython doesn't attempt to retrieve disk usage information from non-mounted filesystems.

  在 3.3 版被加入.

  在 3.8 版的變更: On Windows, path can now be a file or directory.

  Availability: Unix, Windows.

shutil.chown(path, user=None, group=None)

  Change owner user and/or group of the given path.

  user can be a system user name or a uid; the same applies to group. At least one argument is required.

  See also `os.chown()`, the underlying function.

  引發一個附帶引數 `path`、`user`、`group` 的稽核事件 `shutil.chown`。

  Availability: Unix.

  在 3.3 版被加入.

shutil.which(cmd, mode=os.F_OK | os.X_OK, path=None)

  Return the path to an executable which would be run if the given cmd was called. If no cmd would be called, return `None`.

  mode is a permission mask passed to `os.access()`, by default determining if the file exists and is executable.

  path is a "`PATH` string" specifying the directories to look in, delimited by `os.pathsep`. When no path is specified, the `PATH` environment variable is read from `os.environ`, falling back to `os.defpath` if it is not set.

  On Windows, the current directory is prepended to the path if mode does not include `os.X_OK`. When the mode does include `os.X_OK`, the Windows API `NeedCurrentDirectoryForExePathW` will be consulted to determine if the current directory should be prepended to path. To avoid consulting the current working directory for executables: set the environment variable `NoDefaultCurrentDirectoryInExePath`.

  Also on Windows, the `PATHEXT` environment variable is used to resolve commands that may not already include an extension. For example, if you call `shutil.which("python")`, `which()` will search `PATHEXT` to know that it should look for `python.exe` within the path directories. For example, on Windows:

      >>> shutil.which("python")
      'C:\\Python33\\python.EXE'

  This is also applied when cmd is a path that contains a directory component:

      >> shutil.which("C:\\Python33\\python")
      'C:\\Python33\\python.EXE'

  在 3.3 版被加入.

  在 3.8 版的變更: The `bytes` type is now accepted. If cmd type is `bytes`, the result type is also `bytes`.

  在 3.12 版的變更: On Windows, the current directory is no longer prepended to the search path if mode includes `os.X_OK` and WinAPI `NeedCurrentDirectoryForExePathW(cmd)` is false, else the current directory is prepended even if it is already in the search path; `PATHEXT` is used now even when cmd includes a directory component or ends with an extension that is in `PATHEXT`; and filenames that have no extension can now be found.

exception shutil.Error

  This exception collects exceptions that are raised during a multi-file operation. For `copytree()`, the exception argument is a list of 3-tuples (srcname, dstname, exception).

### Platform-dependent efficient copy operations

Starting from Python 3.8, all functions involving a file copy (`copyfile()`, `copy()`, `copy2()`, `copytree()`, and `move()`) may use platform-specific "fast-copy" syscalls in order to copy the file more efficiently (see bpo-33671). "fast-copy" means that the copying operation occurs within the kernel, avoiding the use of userspace buffers in Python as in "`outfd.write(infd.read())`".

On macOS fcopyfile is used to copy the file content (not metadata).

On Linux `os.sendfile()` is used.

On Windows `shutil.copyfile()` uses a bigger default buffer size (1 MiB instead of 64 KiB) and a `memoryview()`-based variant of `shutil.copyfileobj()` is used.

If the fast-copy operation fails and no data was written in the destination file then shutil will silently fallback on using less efficient `copyfileobj()` function internally.

在 3.8 版的變更.

### copytree example

An example that uses the `ignore_patterns()` helper:

    from shutil import copytree, ignore_patterns

    copytree(source, destination, ignore=ignore_patterns('*.pyc', 'tmp*'))

This will copy everything except `.pyc` files and files or directories whose name starts with `tmp`.

Another example that uses the ignore argument to add a logging call:

    from shutil import copytree
    import logging

    def _logpath(path, names):
        logging.info('Working in %s', path)
        return []   # nothing will be ignored

    copytree(source, destination, ignore=_logpath)

### rmtree 範例

This example shows how to remove a directory tree on Windows where some of the files have their read-only bit set. It uses the onexc callback to clear the readonly bit and reattempt the remove. Any subsequent failure will propagate.

    import os, stat
    import shutil

    def remove_readonly(func, path, _):
        "Clear the readonly bit and reattempt the removal"
        os.chmod(path, stat.S_IWRITE)
        func(path)

    shutil.rmtree(directory, onexc=remove_readonly)

## Archiving operations

在 3.2 版被加入.

在 3.5 版的變更: 新增 xztar 格式的支援。

High-level utilities to create and read compressed and archived files are also provided. They rely on the `zipfile` and `tarfile` modules.

shutil.make_archive(base_name, format[, root_dir[, base_dir[, verbose[, dry_run[, owner[, group[, logger]]]]]]])

  Create an archive file (such as zip or tar) and return its name.

  base_name is the name of the file to create, including the path, minus any format-specific extension.

  format is the archive format: one of "zip" (if the `zlib` module is available), "tar", "gztar" (if the `zlib` module is available), "bztar" (if the `bz2` module is available), or "xztar" (if the `lzma` module is available).

  root_dir is a directory that will be the root directory of the archive, all paths in the archive will be relative to it; for example, we typically chdir into root_dir before creating the archive.

  base_dir is the directory where we start archiving from; i.e. base_dir will be the common prefix of all files and directories in the archive. base_dir must be given relative to root_dir. See Archiving example with base_dir for how to use base_dir and root_dir together.

  root_dir and base_dir both default to the current directory.

  If dry_run is true, no archive is created, but the operations that would be executed are logged to logger.

  owner and group are used when creating a tar archive. By default, uses the current owner and group.

  logger must be an object compatible with PEP 282, usually an instance of `logging.Logger`.

  The verbose argument is unused and deprecated.

  引發一個附帶引數 `base_name`、`format`、`root_dir`、`base_dir` 的稽核事件 `shutil.make_archive`。

  備註

  This function is not thread-safe when custom archivers registered with `register_archive_format()` do not support the root_dir argument. In this case it temporarily changes the current working directory of the process to root_dir to perform archiving.

  在 3.8 版的變更: The modern pax (POSIX.1-2001) format is now used instead of the legacy GNU format for archives created with `format="tar"`.

  在 3.10.6 版的變更: This function is now made thread-safe during creation of standard `.zip` and tar archives.

shutil.get_archive_formats()

  Return a list of supported formats for archiving. Each element of the returned sequence is a tuple `(name, description)`.

  By default `shutil` provides these formats:

  - zip: ZIP file (if the `zlib` module is available).

  - tar: Uncompressed tar file. Uses POSIX.1-2001 pax format for new archives.

  - gztar: gzip'ed tar-file (if the `zlib` module is available).

  - bztar: bzip2'ed tar-file (if the `bz2` module is available).

  - xztar: xz'ed tar-file (if the `lzma` module is available).

  You can register new formats or provide your own archiver for any existing formats, by using `register_archive_format()`.

shutil.register_archive_format(name, function[, extra_args[, description]])

  Register an archiver for the format name.

  function is the callable that will be used to unpack archives. The callable will receive the base_name of the file to create, followed by the base_dir (which defaults to `os.curdir`) to start archiving from. Further arguments are passed as keyword arguments: owner, group, dry_run and logger (as passed in `make_archive()`).

  If function has the custom attribute `function.supports_root_dir` set to `True`, the root_dir argument is passed as a keyword argument. Otherwise the current working directory of the process is temporarily changed to root_dir before calling function. In this case `make_archive()` is not thread-safe.

  If given, extra_args is a sequence of `(name, value)` pairs that will be used as extra keywords arguments when the archiver callable is used.

  description is used by `get_archive_formats()` which returns the list of archivers. Defaults to an empty string.

  在 3.12 版的變更: Added support for functions supporting the root_dir argument.

shutil.unregister_archive_format(name)

  Remove the archive format name from the list of supported formats.

shutil.unpack_archive(filename[, extract_dir[, format[, filter]]])

  Unpack an archive. filename is the full path of the archive.

  extract_dir is the name of the target directory where the archive is unpacked. If not provided, the current working directory is used.

  format is the archive format: one of "zip", "tar", "gztar", "bztar", or "xztar". Or any other format registered with `register_unpack_format()`. If not provided, `unpack_archive()` will use the archive file name extension and see if an unpacker was registered for that extension. In case none is found, a `ValueError` is raised.

  The keyword-only filter argument is passed to the underlying unpacking function. For zip files, filter is not accepted. For tar files, it is recommended to set it to `'data'`, unless using features specific to tar and UNIX-like filesystems. (See Extraction filters for details.) The `'data'` filter will become the default for tar files in Python 3.14.

  引發一個附帶引數 `filename`、`extract_dir`、`format` 的稽核事件 `shutil.unpack_archive`。

  警告

  Never extract archives from untrusted sources without prior inspection. It is possible that files are created outside of the path specified in the extract_dir argument, e.g. members that have absolute filenames starting with "/" or filenames with two dots "..".

  在 3.7 版的變更: Accepts a path-like object for filename and extract_dir.

  在 3.12 版的變更: 新增 filter 引數。

shutil.register_unpack_format(name, extensions, function[, extra_args[, description]])

  Registers an unpack format. name is the name of the format and extensions is a list of extensions corresponding to the format, like `.zip` for Zip files.

  function is the callable that will be used to unpack archives. The callable will receive:

  - the path of the archive, as a positional argument;

  - the directory the archive must be extracted to, as a positional argument;

  - possibly a filter keyword argument, if it was given to `unpack_archive()`;

  - additional keyword arguments, specified by extra_args as a sequence of `(name, value)` tuples.

  description can be provided to describe the format, and will be returned by the `get_unpack_formats()` function.

shutil.unregister_unpack_format(name)

  Unregister an unpack format. name is the name of the format.

shutil.get_unpack_formats()

  Return a list of all registered formats for unpacking. Each element of the returned sequence is a tuple `(name, extensions, description)`.

  By default `shutil` provides these formats:

  - zip: ZIP file (unpacking compressed files works only if the corresponding module is available).

  - tar: uncompressed tar file.

  - gztar: gzip'ed tar-file (if the `zlib` module is available).

  - bztar: bzip2'ed tar-file (if the `bz2` module is available).

  - xztar: xz'ed tar-file (if the `lzma` module is available).

  You can register new formats or provide your own unpacker for any existing formats, by using `register_unpack_format()`.

### Archiving example

In this example, we create a gzip'ed tar-file archive containing all files found in the `.ssh` directory of the user:

    >>> from shutil import make_archive
    >>> import os
    >>> archive_name = os.path.expanduser(os.path.join('~', 'myarchive'))
    >>> root_dir = os.path.expanduser(os.path.join('~', '.ssh'))
    >>> make_archive(archive_name, 'gztar', root_dir)
    '/Users/tarek/myarchive.tar.gz'

The resulting archive contains:

    $ tar -tzvf /Users/tarek/myarchive.tar.gz
    drwx------ tarek/staff       0 2010-02-01 16:23:40 ./
    -rw-r--r-- tarek/staff     609 2008-06-09 13:26:54 ./authorized_keys
    -rwxr-xr-x tarek/staff      65 2008-06-09 13:26:54 ./config
    -rwx------ tarek/staff     668 2008-06-09 13:26:54 ./id_dsa
    -rwxr-xr-x tarek/staff     609 2008-06-09 13:26:54 ./id_dsa.pub
    -rw------- tarek/staff    1675 2008-06-09 13:26:54 ./id_rsa
    -rw-r--r-- tarek/staff     397 2008-06-09 13:26:54 ./id_rsa.pub
    -rw-r--r-- tarek/staff   37192 2010-02-06 18:23:10 ./known_hosts

### Archiving example with base_dir

In this example, similar to the one above, we show how to use `make_archive()`, but this time with the usage of base_dir. We now have the following directory structure:

    $ tree tmp
    tmp
    └── root
        └── structure
            ├── content
                └── please_add.txt
            └── do_not_add.txt

In the final archive, `please_add.txt` should be included, but `do_not_add.txt` should not. Therefore we use the following:

    >>> from shutil import make_archive
    >>> import os
    >>> archive_name = os.path.expanduser(os.path.join('~', 'myarchive'))
    >>> make_archive(
    ...     archive_name,
    ...     'tar',
    ...     root_dir='tmp/root',
    ...     base_dir='structure/content',
    ... )
    '/Users/tarek/my_archive.tar'

Listing the files in the resulting archive gives us:

    $ python -m tarfile -l /Users/tarek/myarchive.tar
    structure/content/
    structure/content/please_add.txt

## Querying the size of the output terminal

shutil.get_terminal_size(fallback=(columns, lines))

  Get the size of the terminal window.

  For each of the two dimensions, the environment variable, `COLUMNS` and `LINES` respectively, is checked. If the variable is defined and the value is a positive integer, it is used.

  When `COLUMNS` or `LINES` is not defined, which is the common case, the terminal connected to `sys.__stdout__` is queried by invoking `os.get_terminal_size()`.

  If the terminal size cannot be successfully queried, either because the system doesn't support querying, or because we are not connected to a terminal, the value given in `fallback` parameter is used. `fallback` defaults to `(80, 24)` which is the default size used by many terminal emulators.

  The value returned is a named tuple of type `os.terminal_size`.

  See also: The Single UNIX Specification, Version 2, Other Environment Variables.

  在 3.3 版被加入.

  在 3.11 版的變更: The `fallback` values are also used if `os.get_terminal_size()` returns zeroes.