Tmp python что это

Tmp python что это

Tempfile is a Python module used in a situation, where we need to read multiple files, change or access the data in the file, and gives output files based on the result of processed data. Each of the output files produced during the program execution was no longer needed after the program was done. In this case, a problem arose that many output files were created and this cluttered the file system with unwanted files that would require deleting every time the program ran.

In this situation, tempfiles are used to create temporary files so that next time we don’t have to find delete when our program is done with them

Working with temporary files

A temporary file can also be used for securing sensitive data. This module contains many functions to create temporary files and folders, and access them easily.

tempfile — Generate temporary files and directories¶

This module creates temporary files and directories. It works on all supported platforms. TemporaryFile , NamedTemporaryFile , TemporaryDirectory , and SpooledTemporaryFile are high-level interfaces which provide automatic cleanup and can be used as context managers. mkstemp() and mkdtemp() are lower-level functions which require manual cleanup.

All the user-callable functions and constructors take additional arguments which allow direct control over the location and name of temporary files and directories. Files names used by this module include a string of random characters which allows those files to be securely created in shared temporary directories. 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 items:

tempfile. TemporaryFile ( mode = ‘w+b’ , buffering = — 1 , encoding = None , newline = None , suffix = None , prefix = None , dir = None , * , errors = None ) ¶

Return a file-like object that can be used as a temporary storage area. The file is created securely, using the same rules as 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 either not created at all or 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 resulting object can be used as a context manager (see Examples ). On completion of the context or destruction of the file object the temporary file will be removed from the filesystem.

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. buffering, encoding, errors and newline are interpreted as for open() .

The dir, prefix and suffix parameters have the same meaning and defaults as with mkstemp() .

The returned object is a true file object on POSIX platforms. On other platforms, it is a file-like object whose file attribute is the underlying true file object.

The os.O_TMPFILE flag is used if it is available and works (Linux-specific, requires Linux kernel 3.11 or later).

On platforms that are neither Posix nor Cygwin, TemporaryFile is an alias for NamedTemporaryFile.

Raises an auditing event tempfile.mkstemp with argument fullpath .

Changed in version 3.5: The os.O_TMPFILE flag is now used if available.

Changed in version 3.8: Added errors parameter.

This function operates exactly as 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 name attribute of the returned file-like 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). If delete is true (the default), the file is deleted as soon as it is closed. The returned object is always a file-like object whose file attribute is the underlying true file object. This file-like object can be used in a with statement, just like a normal file.

On POSIX (only), a process that is terminated abruptly with SIGKILL cannot automatically delete any NamedTemporaryFiles it created.

Raises an auditing event tempfile.mkstemp with argument fullpath .

Changed in version 3.8: Added errors parameter.

This class operates exactly as TemporaryFile() does, except that data is spooled in memory until the file size exceeds max_size, or until the file’s fileno() method is called, at which point the contents are written to disk and operation proceeds as with TemporaryFile() .

The resulting file has one additional method, rollover() , which causes the file to roll over to an on-disk file regardless of its size.

The returned object is a file-like object whose _file attribute is either an io.BytesIO or io.TextIOWrapper object (depending on whether binary or text mode was specified) or a true file object, depending on whether rollover() has been called. This file-like object can be used in a with statement, just like a normal file.

Changed in version 3.3: the truncate method now accepts a size argument.

Changed in version 3.8: Added errors parameter.

Changed in version 3.11: Fully implements the io.BufferedIOBase and io.TextIOBase abstract base classes (depending on whether binary or text mode was specified).

This class securely creates a temporary directory using the same rules as mkdtemp() . The resulting object can be used as a context manager (see Examples ). On completion of the context or destruction of the temporary directory object, the newly created temporary directory and all its contents are removed from the filesystem.

The directory name can be retrieved from the name attribute of the returned object. When the returned object is used as a context manager, the name will be assigned to the target of the as clause in the with statement, if there is one.

The directory can be explicitly cleaned up by calling the cleanup() method. If ignore_cleanup_errors is true, any unhandled exceptions during explicit or implicit cleanup (such as a PermissionError removing open files on Windows) will be ignored, and the remaining removable items deleted on a “best-effort” basis. Otherwise, errors will be raised in whatever context cleanup occurs (the cleanup() call, exiting the context manager, when the object is garbage-collected or during interpreter shutdown).

Raises an auditing event tempfile.mkdtemp with argument fullpath .

New in version 3.2.

Changed in version 3.10: Added ignore_cleanup_errors parameter.

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 os.O_EXCL flag for 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 TemporaryFile() , the user of mkstemp() is responsible for deleting the temporary file when done with it.

If suffix is not None , the file name will end with that suffix, otherwise there will be no suffix. 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 not None , the file name will begin with that prefix; otherwise, a default prefix is used. The default is the return value of gettempprefix() or gettempprefixb() , as appropriate.

If dir is not None , 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 any of suffix, prefix, and dir are not None , they must be the same type. If they are bytes, the returned name will be bytes instead of str. If you want to force a bytes return value with otherwise default behavior, pass suffix=b» .

If text is specified and true, the file is opened in text mode. Otherwise, (the default) the file is opened in binary mode.

mkstemp() returns a tuple containing an OS-level handle to an open file (as would be returned by os.open() ) and the absolute pathname of that file, in that order.

Raises an auditing event tempfile.mkstemp with argument fullpath .

Changed in version 3.5: suffix, prefix, and dir may now be supplied in bytes in order to obtain a bytes return value. Prior to this, only str was allowed. suffix and prefix now accept and default to None to cause an appropriate default value to be used.

Changed in version 3.6: The dir parameter now accepts a path-like object .

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 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 mkstemp() .

mkdtemp() returns the absolute pathname of the new directory.

Raises an auditing event tempfile.mkdtemp with argument fullpath .

Changed in version 3.5: suffix, prefix, and dir may now be supplied in bytes in order to obtain a bytes return value. Prior to this, only str was allowed. suffix and prefix now accept and default to None to cause an appropriate default value to be used.

Changed in version 3.6: The dir parameter now accepts a path-like object .

Return the name of the directory used for temporary files. This defines the default value for the dir argument to all functions in this module.

Python searches a standard list of directories to find one which the calling user can create files in. The list is:

The directory named by the TMPDIR environment variable.

The directory named by the TEMP environment variable.

The directory named by the TMP environment variable.

A platform-specific location:

On Windows, the directories C:\TEMP , C:\TMP , \TEMP , and \TMP , in that order.

On all other platforms, the directories /tmp , /var/tmp , and /usr/tmp , in that order.

As a last resort, the current working directory.

The result of this search is cached, see the description of tempdir below.

Changed in version 3.10: Always returns a str. Previously it would return any tempdir value regardless of type so long as it was not None .

Same as gettempdir() but the return value is in bytes.

New in version 3.5.

Return the filename prefix used to create temporary files. This does not contain the directory component.

Same as gettempprefix() but the return value is in bytes.

New in version 3.5.

The module uses a global variable to store the name of the directory used for temporary files returned by gettempdir() . It can be set directly to override the selection process, but this is discouraged. All functions in this module take a dir argument which can be used to specify the directory. This is the recommended approach that does not surprise other unsuspecting code by changing global API behavior.

When set to a value other than None , this variable defines the default value for the dir argument to the functions defined in this module, including its type, bytes or str. It cannot be a path-like object .

If tempdir is None (the default) at any call to any of the above functions except gettempprefix() it is initialized following the algorithm described in gettempdir() .

Beware that if you set tempdir to a bytes value, there is a nasty side effect: The global default return type of mkstemp() and mkdtemp() changes to bytes when no explicit prefix , suffix , or dir arguments of type str are supplied. Please do not write code expecting or depending on this. This awkward behavior is maintained for compatibility with the historical implementation.

Examples¶

Here are some examples of typical usage of the tempfile module:

Deprecated functions and variables¶

A historical way to create temporary files was to first generate a file name with the mktemp() function and then create a file using this name. Unfortunately this is not secure, because a different process may create a file with this name in the time between the call to mktemp() and the subsequent attempt to create the file by the first process. The solution is to combine the two steps and create the file immediately. This approach is used by mkstemp() and the other functions described above.

tempfile. mktemp ( suffix = » , prefix = ‘tmp’ , dir = None ) ¶

Deprecated since version 2.3: Use 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 similar to those of mkstemp() , except that bytes file names, suffix=None and prefix=None are not supported.

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. mktemp() usage can be replaced easily with NamedTemporaryFile() , passing it the delete=False parameter:

temp files and tempfile module in python(with examples)

First lets understand what a temp or temporary file is.

1. A temporary file is created by a program that serves a temporary purpose and is created due to various reasons such as temporary backup, when a program is manipulating data larger than the systems capability or to break up larger chunks of data into pieces that are easy to process.
2. Temp files have the extension as “.tmp” but they are program dependent(i.e different programs create different temp files).

Most common examples of temp files are

1. Temp Internet Files: This files contain cached info on frequent and recent pages so that these sites load faster.
2. Microsoft Office: For example if an office file is closed abruptly, and when we open that file again we get a message from office to restore previous this data is recovered from the the temporary files associated with the file.

These temp files are updated regularly, but not so often that all work is always saved. Now let's talk about pythons tempfile module.

The tempfile module provides various functionalities to create temporary files.

1. TemporaryFile(): opens and returns unnamed files.
2. NamedTemporaryFile(): opens and returns named file.
3. SpooledTemporaryFile(): Holds files content in memory before writing to disk.
4. TemporaryDirectory: is context manager that removes the directory when the context is closed.

Now let's understand each function in detail.

TemporaryFile

tempfile.TemporaryFile(mode='w+b', buffering=None, encoding=None, newline=None, suffix=None, prefix=None, dir=None, *, errors=None)

1. Returns a file like object that can be used as a temporary storage area. It will be destroyed as soon as it is closed.
2. Under Unix, the directory entry for this file is not created, and other OS do not support this functionality hence This function should be avoided.
3. If suffix is not None the file will end up with that suffix or there will be no suffix . Same applies for the prefix .
4. If the dir is not None the file will be created in the same directory else a default directory is used
5. If suffix,prefix and dir are not None They must be of same type . For example is they are bytes the returned value will also be in bytes.

1. Applications that need temporary files to store data, without needing to share that file with other programs.
2. This function creates a file, and on platforms where it is possible, unlinks it immediately this makes impossible for other programs to find or open the file, since there is no reference to the file in the file system table.
3. The file created by TemporaryFile() is removed immediately when it is closed either by calling close() or using with statement.

Anonymous temp files are secure because they are not registered in the file system. But if we include dir or prefix or suffix it makes the file less secure but this files can be used for debugging purpose. All the below defined functions take this parameters.

The names are generated using the formula.

The output follows above formula

NamedTemporaryFile

tempfile.NamedTemporaryFile(mode='w+b', buffering=None, encoding=None, newline=None, suffix=None, prefix=None, dir=None, delete=True, *, errors=None)

1. The function behaviour is similar to TemporaryFile() except that the file is guaranteed to have visible name in the file system.
2. The name can be retrieved from name method of the tempfile object.
3. If delete is true the file is deleted as soon as the it is closed.

For applications spanning multiple processes or event hosts, naming the file is simplest way to pass it between applications.

SpooledTemporaryFile

tempfile.SpooledTemporaryFile(max_size=0, mode='w+b', buffering=None, encoding=None, newline=None, suffix=None, prefix=None, dir=None, *, errors=None)

1. Operates same like TemporaryFile() except the data is spooled in the memory(data is stored in memory except on the disk) until the file exceeds max_size or the fileno method is called.
2. Once the file exceeds max_size or fileno() is called the contents are written to disk and the operation proceeds with TemporaryFile() .
3. The rollover() method causes the file to rollover to disk regardless of the file size.

return

1. The function returns file like object whose _file attribute is either io.BytesIO or io.TextIOWrapper object depending on whether the file was opened in binary or text mode.(because this function holds the file contents in memory using io.BytesIO or io.TextIOWrapper buffer until they reach max_size ).
2. Or returns a TemporaryFileobject if the rollover() method is called.

TemporaryDirectory

tempfile.TemporaryDirectory(suffix=None, prefix=None, dir=None)

Модуль Tempfile в Python

На всех языках программирования часто этой программе требуется сохранять временные данные в файловой системе, создавая временные каталоги и файлы. Эти данные могут быть не полностью готовы для вывода, но все же доступ к этим данным может принести в жертву уровень безопасности программы.

Написание полного кода для простого управления временными данными также является громоздким процессом. Это связано с тем, что нам нужно написать логику создания случайных имен для этих файлов и каталогов, а затем записи в них с последующим удалением данных после завершения всех операций.

Все эти шаги очень легко выполняются с помощью модуля tempfile в Python. Он предоставляет простые функции, с помощью которых мы можем создавать временные файлы и каталоги, а также легко получать к ним доступ. Давайте посмотрим здесь на этот модуль в действии.

Создание временных файлов

Когда нам нужно создать временный файл для хранения данных, нам нужна функция TemporaryFile(). Преимущество этой функции заключается в том, что когда она создает новый файл, в файловой системе платформы нет ссылок на файл, и поэтому другие программы не могут получить доступ к этим файлам.

Вот пример программы в Python, которая создает временный файл и очищает его при закрытии TemporaryFile:

Посмотрим на результат этой программы:

В первом фрагменте кода мы очищаем файл самостоятельно. В следующем фрагменте кода, как только TemporaryFile закрывается, файл также полностью удаляется из системы.

Запустив эту программу, вы увидите, что в файловой системе вашего компьютера нет файлов.

Чтение из временного файла

К счастью, чтение всех данных из временного файла – это всего лишь вызов одной функции. Благодаря этому мы можем читать данные, которые мы записываем в файл, не обрабатывая их побайтно и не выполняя сложных операций ввода-вывода.

Давайте посмотрим на фрагмент кода, чтобы продемонстрировать это:

Посмотрим на результат этой программы:

Нам нужно было только вызвать функцию read() для объекта TemporaryFile(), и мы смогли получить обратно все данные из временного файла. Наконец, обратите внимание, что мы записали в этот файл только байтовые данные. В следующем примере мы запишем в него данные в виде обычного текста.

Запись простого текста во временный файл

С небольшими изменениями в последней написанной нами программе мы также можем записывать простые текстовые данные во временный файл:

Посмотрим на результат этой программы:

Создание именованных временных файлов

Именованные временные файлы важны, потому что могут быть сценарии и приложения, которые охватывают несколько процессов или даже машин. Если мы назовем временный файл, его легко будет передавать между частями приложения.

Давайте посмотрим на фрагмент кода, который использует функцию NamedTemporaryFile() для создания именованного временного файла:

Посмотрим на результат этой программы:

Предоставление суффикса и префикса имени файла

Иногда нам нужно иметь некоторый префикс и суффикс в именах файлов, чтобы определить цель, которую выполняет файл. Таким образом, мы можем создать несколько файлов, чтобы их было легко идентифицировать в группе файлов о том, какой файл выполняет определенную цель.

Вот пример программы, которая предоставляет префикс и суффикс в имена файлов:

Посмотрим на результат этой программы:

Заключение

В этом уроке мы изучили, как можно безопасно создавать временные файлы в Python для наших программ и приложений. Мы также увидели, как мы можем создавать файлы, которые могут охватывать несколько процессов, и увидели, как мы можем предоставить суффикс префикса для имен файлов, чтобы они легко указывали, какие данные они содержат.