6.19 tempfile -- Generate temporary file names
Keywords: lib

# 6.19 `tempfile` -- Generate temporary file names

This module generates temporary file names. It is not Unix specific, but it may require some help on non-Unix systems.

The module defines the following user-callable functions:

`mktemp`([suffix])
  Return a unique temporary filename. This is an absolute pathname of a file that does not exist at the time the call is made. No two calls will return the same filename. suffix, if provided, is used as the last part of the generated file name. This can be used to provide a filename extension or other identifying information that may be useful on some platforms.

`TemporaryFile`([mode[, bufsize[, suffix]]])
  Return a file (or file-like) object that can be used as a temporary storage area. The file is created in the most secure manner available in the appropriate temporary directory for the host platform. Under Unix, the directory entry to the file is removed so that it is secure against attacks which involve creating symbolic links to the file or replacing the file with a symbolic link to some other file. For other platforms, which don't allow removing the directory entry while the file is in use, the file is automatically deleted as soon as it is closed (including an implicit close when it is garbage-collected).

  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. suffix is passed to `mktemp()`.

The module uses two global variables that tell it how to construct a temporary name. The caller may assign values to them; by default they are initialized at the first call to `mktemp()`.

`tempdir`
  When set to a value other than `None`, this variable defines the directory in which filenames returned by `mktemp()` reside. The default is taken from the environment variable TMPDIR; if this is not set, either /usr/tmp is used (on Unix), or the current working directory (all other systems). No check is made to see whether its value is valid.

`gettempprefix`()
  Return the filename prefix used to create temporary files. This does not contain the directory component. Using this function is preferred over using the `template` variable directly. New in version 1.5.2.

`template`
  Deprecated since release 2.0. Use `gettempprefix()` instead.

  When set to a value other than `None`, this variable defines the prefix of the final component of the filenames returned by `mktemp()`. A string of decimal digits is added to generate unique filenames. The default is either @pid. where pid is the current process ID (on Unix), ~pid- on Windows NT, Python-Tmp- on MacOS, or tmp (all other systems).

  Older versions of this module used to require that `template` be set to `None` after a call to `os.fork()`; this has not been necessary since version 1.5.2.