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svn+ssh://pythondev@svn.python.org/python/trunk ........ r59923 | raymond.hettinger | 2008-01-11 19:04:55 +0100 (Fri, 11 Jan 2008) | 1 line Speed-up and simplify code urlparse's result objects. ........ r59924 | andrew.kuchling | 2008-01-11 20:33:24 +0100 (Fri, 11 Jan 2008) | 1 line Bug #1790: update link; remove outdated paragraph ........ r59925 | thomas.heller | 2008-01-11 20:34:06 +0100 (Fri, 11 Jan 2008) | 5 lines Raise an error instead of crashing with a segfault when a NULL function pointer is called. Will backport to release25-maint. ........ r59927 | thomas.heller | 2008-01-11 21:29:19 +0100 (Fri, 11 Jan 2008) | 4 lines Fix a potential 'SystemError: NULL result without error'. NULL may be a valid return value from PyLong_AsVoidPtr. Will backport to release25-maint. ........ r59928 | raymond.hettinger | 2008-01-12 00:25:18 +0100 (Sat, 12 Jan 2008) | 1 line Update the opcode docs for STORE_MAP and BUILD_MAP ........ r59929 | mark.dickinson | 2008-01-12 02:56:00 +0100 (Sat, 12 Jan 2008) | 4 lines Issue 1780: Allow leading and trailing whitespace in Decimal constructor, when constructing from a string. Disallow trailing newlines in Context.create_decimal. ........ r59930 | georg.brandl | 2008-01-12 11:53:29 +0100 (Sat, 12 Jan 2008) | 3 lines Move OSError docs to exceptions doc, remove obsolete descriptions from os docs, rework posix docs. ........ r59931 | georg.brandl | 2008-01-12 14:47:57 +0100 (Sat, 12 Jan 2008) | 3 lines Patch #1700288: Method cache optimization, by Armin Rigo, ported to 2.6 by Kevin Jacobs. ........ r59932 | georg.brandl | 2008-01-12 17:11:09 +0100 (Sat, 12 Jan 2008) | 2 lines Fix editing glitch. ........
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3.4 KiB
ReStructuredText
85 lines
3.4 KiB
ReStructuredText
:mod:`posix` --- The most common POSIX system calls
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===================================================
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.. module:: posix
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:platform: Unix
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:synopsis: The most common POSIX system calls (normally used via module os).
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This module provides access to operating system functionality that is
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standardized by the C Standard and the POSIX standard (a thinly disguised Unix
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interface).
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.. index:: module: os
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**Do not import this module directly.** Instead, import the module :mod:`os`,
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which provides a *portable* version of this interface. On Unix, the :mod:`os`
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module provides a superset of the :mod:`posix` interface. On non-Unix operating
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systems the :mod:`posix` module is not available, but a subset is always
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available through the :mod:`os` interface. Once :mod:`os` is imported, there is
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*no* performance penalty in using it instead of :mod:`posix`. In addition,
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:mod:`os` provides some additional functionality, such as automatically calling
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:func:`putenv` when an entry in ``os.environ`` is changed.
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Errors are reported as exceptions; the usual exceptions are given for type
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errors, while errors reported by the system calls raise :exc:`OSError`.
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.. _posix-large-files:
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Large File Support
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------------------
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.. index::
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single: large files
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single: file; large files
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.. sectionauthor:: Steve Clift <clift@mail.anacapa.net>
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Several operating systems (including AIX, HP-UX, Irix and Solaris) provide
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support for files that are larger than 2 GB from a C programming model where
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:ctype:`int` and :ctype:`long` are 32-bit values. This is typically accomplished
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by defining the relevant size and offset types as 64-bit values. Such files are
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sometimes referred to as :dfn:`large files`.
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Large file support is enabled in Python when the size of an :ctype:`off_t` is
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larger than a :ctype:`long` and the :ctype:`long long` type is available and is
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at least as large as an :ctype:`off_t`.
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It may be necessary to configure and compile Python with certain compiler flags
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to enable this mode. For example, it is enabled by default with recent versions
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of Irix, but with Solaris 2.6 and 2.7 you need to do something like::
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CFLAGS="`getconf LFS_CFLAGS`" OPT="-g -O2 $CFLAGS" \
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./configure
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On large-file-capable Linux systems, this might work::
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CFLAGS='-D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64' OPT="-g -O2 $CFLAGS" \
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./configure
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.. _posix-contents:
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Notable Module Contents
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-----------------------
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In addition to many functions described in the :mod:`os` module documentation,
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:mod:`posix` defines the following data item:
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.. data:: environ
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A dictionary representing the string environment at the time the interpreter
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was started. For example, ``environ['HOME']`` is the pathname of your home
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directory, equivalent to ``getenv("HOME")`` in C.
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Modifying this dictionary does not affect the string environment passed on by
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:func:`execv`, :func:`popen` or :func:`system`; if you need to change the
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environment, pass ``environ`` to :func:`execve` or add variable assignments and
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export statements to the command string for :func:`system` or :func:`popen`.
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.. note::
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The :mod:`os` module provides an alternate implementation of ``environ`` which
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updates the environment on modification. Note also that updating ``os.environ``
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will render this dictionary obsolete. Use of the :mod:`os` module version of
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this is recommended over direct access to the :mod:`posix` module.
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