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author | Georg Brandl <georg@python.org> | 2007-08-15 14:28:22 (GMT) |
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committer | Georg Brandl <georg@python.org> | 2007-08-15 14:28:22 (GMT) |
commit | 116aa62bf54a39697e25f21d6cf6799f7faa1349 (patch) | |
tree | 8db5729518ed4ca88e26f1e26cc8695151ca3eb3 /Doc/library/tempfile.rst | |
parent | 739c01d47b9118d04e5722333f0e6b4d0c8bdd9e (diff) | |
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Move the 3k reST doc tree in place.
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diff --git a/Doc/library/tempfile.rst b/Doc/library/tempfile.rst new file mode 100644 index 0000000..cafdd05 --- /dev/null +++ b/Doc/library/tempfile.rst @@ -0,0 +1,216 @@ + +:mod:`tempfile` --- Generate temporary files and directories +============================================================ + +.. sectionauthor:: Zack Weinberg <zack@codesourcery.com> + + +.. module:: tempfile + :synopsis: Generate temporary files and directories. + + +.. index:: + pair: temporary; file name + pair: temporary; file + +This module generates temporary files and directories. It works on all +supported platforms. + +In version 2.3 of Python, this module was overhauled for enhanced security. It +now provides three new functions, :func:`NamedTemporaryFile`, :func:`mkstemp`, +and :func:`mkdtemp`, which should eliminate all remaining need to use the +insecure :func:`mktemp` function. Temporary file names created by this module +no longer contain the process ID; instead a string of six random characters is +used. + +Also, all the user-callable functions now take additional arguments which allow +direct control over the location and name of temporary files. It is no longer +necessary to use the global *tempdir* and *template* variables. To maintain +backward compatibility, the argument order is somewhat odd; it is recommended to +use keyword arguments for clarity. + +The module defines the following user-callable functions: + + +.. function:: TemporaryFile([mode='w+b'[, bufsize=-1[, suffix[, prefix[, dir]]]]]) + + Return a file (or file-like) object that can be used as a temporary storage + area. The file is created using :func:`mkstemp`. It will be destroyed as soon + as it is closed (including an implicit close when the object is garbage + collected). Under Unix, the directory entry for the file is removed immediately + after the file is created. Other platforms do not support this; your code + should not rely on a temporary file created using this function having or not + having a visible name in the file system. + + The *mode* parameter defaults to ``'w+b'`` so that the file created can be read + and written without being closed. Binary mode is used so that it behaves + consistently on all platforms without regard for the data that is stored. + *bufsize* defaults to ``-1``, meaning that the operating system default is used. + + The *dir*, *prefix* and *suffix* parameters are passed to :func:`mkstemp`. + + +.. function:: NamedTemporaryFile([mode='w+b'[, bufsize=-1[, suffix[, prefix[, dir[, delete]]]]]]) + + This function operates exactly as :func:`TemporaryFile` does, except that the + file is guaranteed to have a visible name in the file system (on Unix, the + directory entry is not unlinked). That name can be retrieved from the + :attr:`name` member of the file object. Whether the name can be used to open + the file a second time, while the named temporary file is still open, varies + across platforms (it can be so used on Unix; it cannot on Windows NT or later). + If *delete* is true (the default), the file is deleted as soon as it is closed. + + .. versionadded:: 2.3 + + .. versionadded:: 2.6 + The *delete* parameter. + + +.. function:: SpooledTemporaryFile([max_size=0, [mode='w+b'[, bufsize=-1[, suffix[, prefix[, dir]]]]]]) + + This function operates exactly as :func:`TemporaryFile` does, except that data + is spooled in memory until the file size exceeds *max_size*, or until the file's + :func:`fileno` method is called, at which point the contents are written to disk + and operation proceeds as with :func:`TemporaryFile`. + + The resulting file has one additional method, :func:`rollover`, which causes the + file to roll over to an on-disk file regardless of its size. + + .. versionadded:: 2.6 + + +.. function:: mkstemp([suffix[, prefix[, dir[, text]]]]) + + Creates a temporary file in the most secure manner possible. There are no + race conditions in the file's creation, assuming that the platform properly + implements the :const:`os.O_EXCL` flag for :func:`os.open`. The file is + readable and writable only by the creating user ID. If the platform uses + permission bits to indicate whether a file is executable, the file is + executable by no one. The file descriptor is not inherited by child + processes. + + Unlike :func:`TemporaryFile`, the user of :func:`mkstemp` is responsible for + deleting the temporary file when done with it. + + If *suffix* is specified, the file name will end with that suffix, otherwise + there will be no suffix. :func:`mkstemp` does not put a dot between the file + name and the suffix; if you need one, put it at the beginning of *suffix*. + + If *prefix* is specified, the file name will begin with that prefix; otherwise, + a default prefix is used. + + If *dir* is specified, the file will be created in that directory; otherwise, + a default directory is used. The default directory is chosen from a + platform-dependent list, but the user of the application can control the + directory location by setting the *TMPDIR*, *TEMP* or *TMP* environment + variables. There is thus no guarantee that the generated filename will have + any nice properties, such as not requiring quoting when passed to external + commands via ``os.popen()``. + + If *text* is specified, it indicates whether to open the file in binary mode + (the default) or text mode. On some platforms, this makes no difference. + + :func:`mkstemp` returns a tuple containing an OS-level handle to an open file + (as would be returned by :func:`os.open`) and the absolute pathname of that + file, in that order. + + .. versionadded:: 2.3 + + +.. function:: mkdtemp([suffix[, prefix[, dir]]]) + + Creates a temporary directory in the most secure manner possible. There are no + race conditions in the directory's creation. The directory is readable, + writable, and searchable only by the creating user ID. + + The user of :func:`mkdtemp` is responsible for deleting the temporary directory + and its contents when done with it. + + The *prefix*, *suffix*, and *dir* arguments are the same as for :func:`mkstemp`. + + :func:`mkdtemp` returns the absolute pathname of the new directory. + + .. versionadded:: 2.3 + + +.. function:: mktemp([suffix[, prefix[, dir]]]) + + .. deprecated:: 2.3 + Use :func:`mkstemp` instead. + + Return an absolute pathname of a file that did not exist at the time the call is + made. The *prefix*, *suffix*, and *dir* arguments are the same as for + :func:`mkstemp`. + + .. warning:: + + Use of this function may introduce a security hole in your program. By the time + you get around to doing anything with the file name it returns, someone else may + have beaten you to the punch. + +The module uses two global variables that tell it how to construct a temporary +name. They are initialized at the first call to any of the functions above. +The caller may change them, but this is discouraged; use the appropriate +function arguments, instead. + + +.. data:: tempdir + + When set to a value other than ``None``, this variable defines the default value + for the *dir* argument to all the functions defined in this module. + + If ``tempdir`` is unset or ``None`` at any call to any of the above functions, + Python searches a standard list of directories and sets *tempdir* to the first + one which the calling user can create files in. The list is: + + #. The directory named by the :envvar:`TMPDIR` environment variable. + + #. The directory named by the :envvar:`TEMP` environment variable. + + #. The directory named by the :envvar:`TMP` environment variable. + + #. A platform-specific location: + + * On RiscOS, the directory named by the :envvar:`Wimp$ScrapDir` environment + variable. + + * On Windows, the directories :file:`C:\\TEMP`, :file:`C:\\TMP`, + :file:`\\TEMP`, and :file:`\\TMP`, in that order. + + * On all other platforms, the directories :file:`/tmp`, :file:`/var/tmp`, and + :file:`/usr/tmp`, in that order. + + #. As a last resort, the current working directory. + + +.. function:: gettempdir() + + Return the directory currently selected to create temporary files in. If + :data:`tempdir` is not ``None``, this simply returns its contents; otherwise, + the search described above is performed, and the result returned. + + +.. data:: template + + .. deprecated:: 2.0 + Use :func:`gettempprefix` instead. + + When set to a value other than ``None``, this variable defines the prefix of the + final component of the filenames returned by :func:`mktemp`. A string of six + random letters and digits is appended to the prefix to make the filename unique. + On Windows, the default prefix is :file:`~T`; on all other systems it is + :file:`tmp`. + + Older versions of this module used to require that ``template`` be set to + ``None`` after a call to :func:`os.fork`; this has not been necessary since + version 1.5.2. + + +.. function:: gettempprefix() + + Return the filename prefix used to create temporary files. This does not + contain the directory component. Using this function is preferred over reading + the *template* variable directly. + + .. versionadded:: 1.5.2 + |