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110 lines
4.3 KiB
TeX
110 lines
4.3 KiB
TeX
\section{Standard Module \sectcode{os}}
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\label{module-os}
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\stmodindex{os}
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This module provides a more portable way of using operating system
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(OS) dependent functionality than importing an OS dependent built-in
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module like \module{posix}.
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When the optional built-in module \module{posix} is available, this
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module exports the same functions and data as \module{posix}; otherwise,
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it searches for an OS dependent built-in module like \module{mac} and
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exports the same functions and data as found there. The design of all
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Python's built-in OS dependent modules is such that as long as the same
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functionality is available, it uses the same interface; e.g., the
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function \code{os.stat(\var{file})} returns stat info about \var{file}
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in a format compatible with the \POSIX{} interface.
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Extensions peculiar to a particular OS are also available through the
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\module{os} module, but using them is of course a threat to
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portability!
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Note that after the first time \module{os} is imported, there is
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\emph{no} performance penalty in using functions from \module{os}
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instead of directly from the OS dependent built-in module, so there
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should be \emph{no} reason not to use \module{os}!
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In addition to whatever the correct OS dependent module exports, the
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following variables and functions are always exported by \module{os}:
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\begin{datadesc}{name}
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The name of the OS dependent module imported. The following names
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have currently been registered: \code{'posix'}, \code{'nt'},
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\code{'dos'}, \code{'mac'}.
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\end{datadesc}
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\begin{datadesc}{path}
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The corresponding OS dependent standard module for pathname
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operations, e.g., \module{posixpath} or \module{macpath}. Thus, (given
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the proper imports), \code{os.path.split(\var{file})} is equivalent to but
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more portable than \code{posixpath.split(\var{file})}.
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\end{datadesc}
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\begin{datadesc}{curdir}
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The constant string used by the OS to refer to the current directory,
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e.g. \code{'.'} for \POSIX{} or \code{':'} for the Macintosh.
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\end{datadesc}
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\begin{datadesc}{pardir}
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The constant string used by the OS to refer to the parent directory,
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e.g. \code{'..'} for \POSIX{} or \code{'::'} for the Macintosh.
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\end{datadesc}
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\begin{datadesc}{sep}
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The character used by the OS to separate pathname components,
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e.g. \code{'/'} for \POSIX{} or \code{':'} for the Macintosh. Note that
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knowing this is not sufficient to be able to parse or concatenate
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pathnames --- better use \function{os.path.split()} and
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\function{os.path.join()}---but it is occasionally useful.
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\end{datadesc}
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\begin{datadesc}{altsep}
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An alternative character used by the OS to separate pathname components,
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or \code{None} if only one separator character exists. This is set to
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\code{'/'} on DOS/Windows systems where \code{sep} is a backslash.
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\end{datadesc}
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\begin{datadesc}{pathsep}
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The character conventionally used by the OS to separate search patch
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components (as in \code{\$PATH}), e.g.\ \code{':'} for \POSIX{} or
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\code{';'} for MS-DOS.
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\end{datadesc}
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\begin{datadesc}{defpath}
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The default search path used by \code{exec*p*()} if the environment
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doesn't have a \code{'PATH'} key.
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\end{datadesc}
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\begin{funcdesc}{execl}{path, arg0, arg1, ...}
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This is equivalent to
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\code{execv(\var{path}, (\var{arg0}, \var{arg1}, ...))}.
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\end{funcdesc}
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\begin{funcdesc}{execle}{path, arg0, arg1, ..., env}
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This is equivalent to
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\code{execve(\var{path}, (\var{arg0}, \var{arg1}, ...), \var{env})}.
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\end{funcdesc}
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\begin{funcdesc}{execlp}{path, arg0, arg1, ...}
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This is equivalent to
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\code{execvp(\var{path}, (\var{arg0}, \var{arg1}, ...))}.
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\end{funcdesc}
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\begin{funcdesc}{execvp}{path, args}
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This is like \code{execv(\var{path}, \var{args})} but duplicates
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the shell's actions in searching for an executable file in a list of
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directories. The directory list is obtained from
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\code{environ['PATH']}.
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\end{funcdesc}
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\begin{funcdesc}{execvpe}{path, args, env}
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This is a cross between \function{execve()} and \function{execvp()}.
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The directory list is obtained from \code{\var{env}['PATH']}.
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\end{funcdesc}
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(The functions \code{execv()} and \code{execve()} are not
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documented here, since they are implemented by the OS dependent
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module. If the OS dependent module doesn't define either of these,
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the functions that rely on it will raise an exception. They are
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documented in the section on module \module{posix}, together with all
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other functions that \module{os} imports from the OS dependent module.)
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