posix — The most common POSIX system calls
This module provides access to operating system functionality that is standardized by the C Standard and the POSIX standard (a thinly disguised Unix interface).
Do not import this module directly. Instead, import the module
os, which provides a portable version of this interface. On Unix, the
os module provides a superset of the
posix interface. On non-Unix operating systems the
posix module is not available, but a subset is always available through the
os interface. Once
os is imported, there is no performance penalty in using it instead of
posix. In addition,
os provides some additional functionality, such as automatically calling
putenv() when an entry in
os.environ is changed.
Errors are reported as exceptions; the usual exceptions are given for type errors, while errors reported by the system calls raise
Several operating systems (including AIX, HP-UX, Irix and Solaris) provide support for files that are larger than 2 GiB from a C programming model where
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 large files.
Large file support is enabled in Python when the size of an
off_t is larger than a
long and the
long long is at least as large as an
off_t. It may be necessary to configure and compile Python with certain compiler flags to enable this mode. For example, it is enabled by default with recent versions of Irix, but with Solaris 2.6 and 2.7 you need to do something like:
CFLAGS="`getconf LFS_CFLAGS`" OPT="-g -O2 $CFLAGS" \ ./configure
On large-file-capable Linux systems, this might work:
CFLAGS='-D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64' OPT="-g -O2 $CFLAGS" \ ./configure
A dictionary representing the string environment at the time the interpreter was started. Keys and values are bytes on Unix and str on Windows. For example,
environ['HOME']on Windows) is the pathname of your home directory, equivalent to
Modifying this dictionary does not affect the string environment passed on by
system(); if you need to change the environment, pass
execve()or add variable assignments and export statements to the command string for
Changed in version 3.2: On Unix, keys and values are bytes.