2 :mod:`tempfile` --- Generate temporary files and directories
3 ============================================================
5 .. sectionauthor:: Zack Weinberg <zack@codesourcery.com>
9 :synopsis: Generate temporary files and directories.
13 pair: temporary; file name
16 This module generates temporary files and directories. It works on all
19 In version 2.3 of Python, this module was overhauled for enhanced security. It
20 now provides three new functions, :func:`NamedTemporaryFile`, :func:`mkstemp`,
21 and :func:`mkdtemp`, which should eliminate all remaining need to use the
22 insecure :func:`mktemp` function. Temporary file names created by this module
23 no longer contain the process ID; instead a string of six random characters is
26 Also, all the user-callable functions now take additional arguments which
27 allow direct control over the location and name of temporary files. It is
28 no longer necessary to use the global *tempdir* and *template* variables.
29 To maintain backward compatibility, the argument order is somewhat odd; it
30 is recommended to use keyword arguments for clarity.
32 The module defines the following user-callable functions:
35 .. function:: TemporaryFile([mode='w+b'[, bufsize=-1[, suffix=''[, prefix='tmp'[, dir=None]]]]])
37 Return a file-like object that can be used as a temporary storage area.
38 The file is created using :func:`mkstemp`. It will be destroyed as soon
39 as it is closed (including an implicit close when the object is garbage
40 collected). Under Unix, the directory entry for the file is removed
41 immediately after the file is created. Other platforms do not support
42 this; your code should not rely on a temporary file created using this
43 function having or not having a visible name in the file system.
45 The *mode* parameter defaults to ``'w+b'`` so that the file created can
46 be read and written without being closed. Binary mode is used so that it
47 behaves consistently on all platforms without regard for the data that is
48 stored. *bufsize* defaults to ``-1``, meaning that the operating system
51 The *dir*, *prefix* and *suffix* parameters are passed to :func:`mkstemp`.
53 The returned object is a true file object on POSIX platforms. On other
54 platforms, it is a file-like object whose :attr:`file` attribute is the
55 underlying true file object. This file-like object can be used in a
56 :keyword:`with` statement, just like a normal file.
59 .. function:: NamedTemporaryFile([mode='w+b'[, bufsize=-1[, suffix=''[, prefix='tmp'[, dir=None[, delete=True]]]]]])
61 This function operates exactly as :func:`TemporaryFile` does, except that
62 the file is guaranteed to have a visible name in the file system (on
63 Unix, the directory entry is not unlinked). That name can be retrieved
64 from the :attr:`name` member of the file object. Whether the name can be
65 used to open the file a second time, while the named temporary file is
66 still open, varies across platforms (it can be so used on Unix; it cannot
67 on Windows NT or later). If *delete* is true (the default), the file is
68 deleted as soon as it is closed.
70 The returned object is always a file-like object whose :attr:`file`
71 attribute is the underlying true file object. This file-like object can
72 be used in a :keyword:`with` statement, just like a normal file.
77 The *delete* parameter.
80 .. function:: SpooledTemporaryFile([max_size=0, [mode='w+b'[, bufsize=-1[, suffix=''[, prefix='tmp'[, dir=None]]]]]])
82 This function operates exactly as :func:`TemporaryFile` does, except that
83 data is spooled in memory until the file size exceeds *max_size*, or
84 until the file's :func:`fileno` method is called, at which point the
85 contents are written to disk and operation proceeds as with
86 :func:`TemporaryFile`.
88 The resulting file has one additional method, :func:`rollover`, which
89 causes the file to roll over to an on-disk file regardless of its size.
91 The returned object is a file-like object whose :attr:`_file` attribute
92 is either a :class:`StringIO` object or a true file object, depending on
93 whether :func:`rollover` has been called. This file-like object can be
94 used in a :keyword:`with` statement, just like a normal file.
99 .. function:: mkstemp([suffix=''[, prefix='tmp'[, dir=None[, text=False]]]])
101 Creates a temporary file in the most secure manner possible. There are
102 no race conditions in the file's creation, assuming that the platform
103 properly implements the :const:`os.O_EXCL` flag for :func:`os.open`. The
104 file is readable and writable only by the creating user ID. If the
105 platform uses permission bits to indicate whether a file is executable,
106 the file is executable by no one. The file descriptor is not inherited
109 Unlike :func:`TemporaryFile`, the user of :func:`mkstemp` is responsible
110 for deleting the temporary file when done with it.
112 If *suffix* is specified, the file name will end with that suffix,
113 otherwise there will be no suffix. :func:`mkstemp` does not put a dot
114 between the file name and the suffix; if you need one, put it at the
115 beginning of *suffix*.
117 If *prefix* is specified, the file name will begin with that prefix;
118 otherwise, a default prefix is used.
120 If *dir* is specified, the file will be created in that directory;
121 otherwise, a default directory is used. The default directory is chosen
122 from a platform-dependent list, but the user of the application can
123 control the directory location by setting the *TMPDIR*, *TEMP* or *TMP*
124 environment variables. There is thus no guarantee that the generated
125 filename will have any nice properties, such as not requiring quoting
126 when passed to external commands via ``os.popen()``.
128 If *text* is specified, it indicates whether to open the file in binary
129 mode (the default) or text mode. On some platforms, this makes no
132 :func:`mkstemp` returns a tuple containing an OS-level handle to an open
133 file (as would be returned by :func:`os.open`) and the absolute pathname
134 of that file, in that order.
136 .. versionadded:: 2.3
139 .. function:: mkdtemp([suffix=''[, prefix='tmp'[, dir=None]]])
141 Creates a temporary directory in the most secure manner possible. There
142 are no race conditions in the directory's creation. The directory is
143 readable, writable, and searchable only by the creating user ID.
145 The user of :func:`mkdtemp` is responsible for deleting the temporary
146 directory and its contents when done with it.
148 The *prefix*, *suffix*, and *dir* arguments are the same as for
151 :func:`mkdtemp` returns the absolute pathname of the new directory.
153 .. versionadded:: 2.3
156 .. function:: mktemp([suffix=''[, prefix='tmp'[, dir=None]]])
159 Use :func:`mkstemp` instead.
161 Return an absolute pathname of a file that did not exist at the time the
162 call is made. The *prefix*, *suffix*, and *dir* arguments are the same
163 as for :func:`mkstemp`.
167 Use of this function may introduce a security hole in your program. By
168 the time you get around to doing anything with the file name it returns,
169 someone else may have beaten you to the punch. :func:`mktemp` usage can
170 be replaced easily with :func:`NamedTemporaryFile`, passing it the
171 ``delete=False`` parameter::
173 >>> f = NamedTemporaryFile(delete=False)
175 <open file '<fdopen>', mode 'w+b' at 0x384698>
177 '/var/folders/5q/5qTPn6xq2RaWqk+1Ytw3-U+++TI/-Tmp-/tmpG7V1Y0'
178 >>> f.write("Hello World!\n")
180 >>> os.unlink(f.name)
181 >>> os.path.exists(f.name)
184 The module uses two global variables that tell it how to construct a
185 temporary name. They are initialized at the first call to any of the
186 functions above. The caller may change them, but this is discouraged; use
187 the appropriate function arguments, instead.
192 When set to a value other than ``None``, this variable defines the
193 default value for the *dir* argument to all the functions defined in this
196 If ``tempdir`` is unset or ``None`` at any call to any of the above
197 functions, Python searches a standard list of directories and sets
198 *tempdir* to the first one which the calling user can create files in.
201 #. The directory named by the :envvar:`TMPDIR` environment variable.
203 #. The directory named by the :envvar:`TEMP` environment variable.
205 #. The directory named by the :envvar:`TMP` environment variable.
207 #. A platform-specific location:
209 * On RiscOS, the directory named by the :envvar:`Wimp$ScrapDir` environment
212 * On Windows, the directories :file:`C:\\TEMP`, :file:`C:\\TMP`,
213 :file:`\\TEMP`, and :file:`\\TMP`, in that order.
215 * On all other platforms, the directories :file:`/tmp`, :file:`/var/tmp`, and
216 :file:`/usr/tmp`, in that order.
218 #. As a last resort, the current working directory.
221 .. function:: gettempdir()
223 Return the directory currently selected to create temporary files in. If
224 :data:`tempdir` is not ``None``, this simply returns its contents; otherwise,
225 the search described above is performed, and the result returned.
227 .. versionadded:: 2.3
233 Use :func:`gettempprefix` instead.
235 When set to a value other than ``None``, this variable defines the prefix of the
236 final component of the filenames returned by :func:`mktemp`. A string of six
237 random letters and digits is appended to the prefix to make the filename unique.
238 The default prefix is :file:`tmp`.
240 Older versions of this module used to require that ``template`` be set to
241 ``None`` after a call to :func:`os.fork`; this has not been necessary since
245 .. function:: gettempprefix()
247 Return the filename prefix used to create temporary files. This does not
248 contain the directory component. Using this function is preferred over reading
249 the *template* variable directly.
251 .. versionadded:: 1.5.2