:mod:os -- basic "operating system" services

.. module:: os :synopsis: basic "operating system" services

|see_cpython_module| :mod:python:os.

The os module contains functions for filesystem access and mounting, terminal redirection and duplication, and the uname and urandom functions.

General functions

.. function:: uname()

Return a tuple (possibly a named tuple) containing information about the underlying machine and/or its operating system. The tuple has five fields in the following order, each of them being a string:

    * ``sysname`` -- the name of the underlying system
    * ``nodename`` -- the network name (can be the same as ``sysname``)
    * ``release`` -- the version of the underlying system
    * ``version`` -- the MicroPython version and build date
    * ``machine`` -- an identifier for the underlying hardware (eg board, CPU)

.. function:: urandom(n)

Return a bytes object with n random bytes. Whenever possible, it is generated by the hardware random number generator.

Filesystem access

.. function:: chdir(path)

Change current directory.

.. function:: getcwd()

Get the current directory.

.. function:: ilistdir([dir])

This function returns an iterator which then yields tuples corresponding to the entries in the directory that it is listing. With no argument it lists the current directory, otherwise it lists the directory given by dir.

The tuples have the form (name, type, inode[, size]):

- *name* is a string (or bytes if *dir* is a bytes object) and is the name of
  the entry;
- *type* is an integer that specifies the type of the entry, with 0x4000 for
  directories and 0x8000 for regular files;
- *inode* is an integer corresponding to the inode of the file, and may be 0
  for filesystems that don't have such a notion.
- *size* is an integer that may be included depending on the filesystem type.
  For file entries, *size* represents the size of the file or -1 if unknown.
  Its meaning is currently undefined for directory entries.

.. function:: listdir([dir])

With no argument, list the current directory. Otherwise list the given directory.

.. function:: mkdir(path)

Create a new directory.

.. function:: remove(path)

Remove a file.

.. function:: rmdir(path)

Remove a directory.

.. function:: rename(old_path, new_path)

Rename a file.

.. function:: stat(path)

Get the status of a file or directory.

.. function:: statvfs(path)

Get the status of a filesystem.

Returns a tuple with the filesystem information in the following order:

    * ``f_bsize`` -- file system block size
    * ``f_frsize`` -- fragment size
    * ``f_blocks`` -- size of fs in f_frsize units
    * ``f_bfree`` -- number of free blocks
    * ``f_bavail`` -- number of free blocks for unprivileged users
    * ``f_files`` -- number of inodes
    * ``f_ffree`` -- number of free inodes
    * ``f_favail`` -- number of free inodes for unprivileged users
    * ``f_flag`` -- mount flags
    * ``f_namemax`` -- maximum filename length

Parameters related to inodes: f_files, f_ffree, f_avail and the f_flags parameter may return 0 as they can be unavailable in a port-specific implementation.

.. function:: sync()

Sync all filesystems.

Terminal redirection and duplication

.. function:: dupterm(stream_object, index=0, /)

Duplicate or switch the MicroPython terminal (the REPL) on the given stream-like object. The stream_object argument must be a native stream object, or derive from io.IOBase and implement the readinto() and write() methods. The stream should be in non-blocking mode and readinto() should return None if there is no data available for reading.

After calling this function all terminal output is repeated on this stream, and any input that is available on the stream is passed on to the terminal input.

The index parameter should be a non-negative integer and specifies which duplication slot is set. A given port may implement more than one slot (slot 0 will always be available) and in that case terminal input and output is duplicated on all the slots that are set.

If None is passed as the stream_object then duplication is cancelled on the slot given by index.

The function returns the previous stream-like object in the given slot.

.. function:: dupterm_notify(obj_in, /)

Notify the MicroPython REPL that input is available on a stream-like object
previously registered via `os.dupterm()`.

This function should be called by custom stream implementations (e.g., UART,
Bluetooth, or other non-USB REPL streams) to inform the REPL that input is
ready to be read. Proper use ensures that special characters such as
Ctrl+C (used to trigger KeyboardInterrupt) are processed promptly by the
REPL, enabling expected interruption behavior for user code.

The *obj_in* parameter is ignored by `os.dupterm_notify()`, but is required to allow calling
dupterm_notify from an interrupt handler such as `UART.irq()`.

Example:

.. code-block:: python

    from machine import UART
    import os
    uart = UART(0)
    os.dupterm(uart, 0)
    uart.irq(os.dupterm_notify, machine.UART.IRQ_RX)

.. note::
    If the ``dupterm_notify()`` function is not called, input from the custom stream
    may not be detected or processed until the next REPL poll, potentially delaying
    KeyboardInterrupts or other control signals.
    This is especially important for UART, Bluetooth and other
    non-standard REPL connections, where automatic notification is not guaranteed.

Filesystem mounting

The following functions and classes have been moved to the :mod:vfs module. They are provided in this module only for backwards compatibility and will be removed in version 2 of MicroPython.

.. function:: mount(fsobj, mount_point, *, readonly)

See `vfs.mount`.

.. function:: umount(mount_point)

See `vfs.umount`.

.. class:: VfsFat(block_dev)

See `vfs.VfsFat`.

.. class:: VfsLfs1(block_dev, readsize=32, progsize=32, lookahead=32)

See `vfs.VfsLfs1`.

.. class:: VfsLfs2(block_dev, readsize=32, progsize=32, lookahead=32, mtime=True)

See `vfs.VfsLfs2`.

.. class:: VfsPosix(root=None)

See `vfs.VfsPosix`.