6.1. Standard Module os

When the optional built-in module posix is available, this module exports the same functions and data as posix; otherwise, it searches for an OS dependent built-in module like mac and exports the same functions and data as found there. The design of all Python's built-in OS dependent modules is such that as long as the same functionality is available, it uses the same interface; e.g., the function os.stat(file) returns stat info about a file in a format compatible with the POSIX interface.

Extensions peculiar to a particular OS are also available through the os module, but using them is of course a threat to portability!

Note that after the first time os is imported, there is no performance penalty in using functions from os instead of directly from the OS dependent built-in module, so there should be no reason not to use os!

In addition to whatever the correct OS dependent module exports, the following variables and functions are always exported by os:

name -- data of module os

The name of the OS dependent module imported. The following names have currently been registered: 'posix', 'nt', 'dos', 'mac'.

path -- data of module os

The corresponding OS dependent standard module for pathname operations, e.g., posixpath or macpath. Thus, (given the proper imports), os.path.split(file) is equivalent to but more portable than posixpath.split(file).

curdir -- data of module os

The constant string used by the OS to refer to the current directory, e.g. '.' for POSIX or ':' for the Mac.

pardir -- data of module os

The constant string used by the OS to refer to the parent directory, e.g. '..' for POSIX or '::' for the Mac.

sep -- data of module os

The character used by the OS to separate pathname components, e.g. '/' for POSIX or ':' for the Mac. Note that knowing this is not sufficient to be able to parse or concatenate pathnames---better use os.path.split() and os.path.join()---but it is occasionally useful.

pathsep -- data of module os

The character conventionally used by the OS to separate search patch components (as in $PATH), e.g. ':' for POSIX or ';' for MS-DOS.

defpath -- data of module os

The default search path used by os.exec*p*() if the environment doesn't have a 'PATH' key.

execl (path, arg0, arg1, ...) -- function of module os

This is equivalent to os.execv(path, (arg0, arg1, ...)).

execle (path, arg0, arg1, ..., env) -- function of module os

This is equivalent to os.execve(path, (arg0, arg1, ...), env).

execlp (path, arg0, arg1, ...) -- function of module os

This is equivalent to os.execvp(path, (arg0, arg1, ...)).

execvp (path, args) -- function of module os

This is like os.execv(path, args) but duplicates the shell's actions in searching for an executable file in a list of directories. The directory list is obtained from os.environ['PATH'].

execvpe (path, args, env) -- function of module os

This is a cross between os.execve() and os.execvp(). The directory list is obtained from env['PATH'].