.. exception:: OSError
- This class is derived from :exc:`EnvironmentError` and is used primarily as the
- :mod:`os` module's ``os.error`` exception. See :exc:`EnvironmentError` above for
- a description of the possible associated values.
+ and is used primarily as
+ the :mod:`os` module's :exc:`os.error` exception. See :exc:`EnvironmentError`
+ above for a description of the possible associated values.
.. versionadded:: 1.5.2
+ .. index:: module: errno
+
+ This exception is derived from :exc:`EnvironmentError`. It is raised when a
+ function returns a system-related error (not for illegal argument types or
+ other incidental errors). The :attr:`errno` attribute is a numeric error
+ code from :cdata:`errno`, and the :attr:`strerror` attribute is the
+ corresponding string, as would be printed by the C function :cfunc:`perror`.
+ See the module :mod:`errno`, which contains names for the error codes defined
+ by the underlying operating system.
+
+ For exceptions that involve a file system path (such as :func:`chdir` or
+ :func:`unlink`), the exception instance will contain a third attribute,
+ :attr:`filename`, which is the file name passed to the function.
.. exception:: OverflowError
-
:mod:`os` --- Miscellaneous operating system interfaces
=======================================================
:synopsis: Miscellaneous operating system interfaces.
-This module provides a more portable way of using operating system dependent
-functionality than importing an operating system dependent built-in module like
-:mod:`posix` or :mod:`nt`. If you just want to read or write a file see
-:func:`open`, if you want to manipulate paths, see the :mod:`os.path`
-module, and if you want to read all the lines in all the files on the
-command line see the :mod:`fileinput` module. For creating temporary
-files and directories see the :mod:`tempfile` module, and for high-level
-file and directory handling see the :mod:`shutil` module.
-
-This module searches for an operating system dependent built-in module like
-:mod:`mac` or :mod:`posix` and exports the same functions and data as found
-there. The design of all built-in operating system dependent modules of Python
-is such that as long as the same functionality is available, it uses the same
-interface; for example, the function ``os.stat(path)`` returns stat information
-about *path* in the same format (which happens to have originated with the POSIX
+This module provides a portable way of using operating system dependent
+functionality. If you just want to read or write a file see :func:`open`, if
+you want to manipulate paths, see the :mod:`os.path` module, and if you want to
+read all the lines in all the files on the command line see the :mod:`fileinput`
+module. For creating temporary files and directories see the :mod:`tempfile`
+module, and for high-level file and directory handling see the :mod:`shutil`
+module.
+
+The design of all built-in operating system dependent modules of Python is such
+that as long as the same functionality is available, it uses the same interface;
+for example, the function ``os.stat(path)`` returns stat information about
+*path* in the same format (which happens to have originated with the POSIX
interface).
Extensions peculiar to a particular operating system are also available through
the :mod:`os` module, but using them is of course a threat to portability!
-Note that after the first time :mod:`os` is imported, there is *no* performance
-penalty in using functions from :mod:`os` instead of directly from the operating
-system dependent built-in module, so there should be *no* reason not to use
-:mod:`os`!
+.. note::
-The :mod:`os` module contains many functions and data values. The items below
-and in the following sub-sections are all available directly from the :mod:`os`
-module.
+ All functions in this module raise :exc:`OSError` in the case of invalid or
+ inaccessible file names and paths, or other arguments that have the correct
+ type, but are not accepted by the operating system.
.. exception:: error
- .. index:: module: errno
-
- This exception is raised when a function returns a system-related error (not for
- illegal argument types or other incidental errors). This is also known as the
- built-in exception :exc:`OSError`. The accompanying value is a pair containing
- the numeric error code from :cdata:`errno` and the corresponding string, as
- would be printed by the C function :cfunc:`perror`. See the module
- :mod:`errno`, which contains names for the error codes defined by the underlying
- operating system.
-
- When exceptions are classes, this exception carries two attributes,
- :attr:`errno` and :attr:`strerror`. The first holds the value of the C
- :cdata:`errno` variable, and the latter holds the corresponding error message
- from :cfunc:`strerror`. For exceptions that involve a file system path (such as
- :func:`chdir` or :func:`unlink`), the exception instance will contain a third
- attribute, :attr:`filename`, which is the file name passed to the function.
+ An alias for the built-in :exc:`OSError` exception.
.. data:: name
Files and Directories
---------------------
-
.. function:: access(path, mode)
Use the real uid/gid to test for access to *path*. Note that most operations
.. function:: getloadavg()
- Return the number of processes in the system run queue averaged over the last 1,
- 5, and 15 minutes or raises :exc:`OSError` if the load average was
+ Return the number of processes in the system run queue averaged over the last
+ 1, 5, and 15 minutes or raises :exc:`OSError` if the load average was
unobtainable.
.. versionadded:: 2.3
-
:mod:`posix` --- The most common POSIX system calls
===================================================
:mod:`os` provides some additional functionality, such as automatically calling
:func:`putenv` when an entry in ``os.environ`` is changed.
-The descriptions below are very terse; refer to the corresponding Unix manual
-(or POSIX documentation) entry for more information. Arguments called *path*
-refer to a pathname given as a string.
-
Errors are reported as exceptions; the usual exceptions are given for type
-errors, while errors reported by the system calls raise :exc:`error` (a synonym
-for the standard exception :exc:`OSError`), described below.
+errors, while errors reported by the system calls raise :exc:`OSError`.
.. _posix-large-files:
.. sectionauthor:: Steve Clift <clift@mail.anacapa.net>
-
-Several operating systems (including AIX, HPUX, Irix and Solaris) provide
-support for files that are larger than 2 Gb from a C programming model where
+Several operating systems (including AIX, HP-UX, Irix and Solaris) provide
+support for files that are larger than 2 GB from a C programming model where
:ctype:`int` and :ctype:`long` are 32-bit values. This is typically accomplished
by defining the relevant size and offset types as 64-bit values. Such files are
sometimes referred to as :dfn:`large files`.
.. _posix-contents:
-Module Contents
----------------
-
-Module :mod:`posix` defines the following data item:
+Notable Module Contents
+-----------------------
+In addition to many functions described in the :mod:`os` module documentation,
+:mod:`posix` defines the following data item:
.. data:: environ
- A dictionary representing the string environment at the time the interpreter was
- started. For example, ``environ['HOME']`` is the pathname of your home
+ A dictionary representing the string environment at the time the interpreter
+ was started. For example, ``environ['HOME']`` is the pathname of your home
directory, equivalent to ``getenv("HOME")`` in C.
Modifying this dictionary does not affect the string environment passed on by
updates the environment on modification. Note also that updating ``os.environ``
will render this dictionary obsolete. Use of the :mod:`os` module version of
this is recommended over direct access to the :mod:`posix` module.
-
-Additional contents of this module should only be accessed via the :mod:`os`
-module; refer to the documentation for that module for further information.
-
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