Doc/libos.tex

   1 \section{Standard Module \sectcode{os}}
   2
   3 \stmodindex{os}
   4 This module provides a more portable way of using operating system
   5 (OS) dependent functionality than importing an OS dependent built-in
   6 module like \code{posix}.
   7
   8 When the optional built-in module \code{posix} is available, this
   9 module exports the same functions and data as \code{posix}; otherwise,
  10 it searches for an OS dependent built-in module like \code{mac} and
  11 exports the same functions and data as found there.  The design of all
  12 Python's built-in OS dependent modules is such that as long as the same
  13 functionality is available, it uses the same interface; e.g., the
  14 function \code{os.stat(\var{file})} returns stat info about a \var{file} in a
  15 format compatible with the POSIX interface.
  16
  17 Extensions peculiar to a particular OS are also available through the
  18 \code{os} module, but using them is of course a threat to portability!
  19
  20 Note that after the first time \code{os} is imported, there is \emph{no}
  21 performance penalty in using functions from \code{os} instead of
  22 directly from the OS dependent built-in module, so there should be
  23 \emph{no} reason not to use \code{os}!
  24
  25 In addition to whatever the correct OS dependent module exports, the
  26 following variables and functions are always exported by \code{os}:
  27
  28 \renewcommand{\indexsubitem}{(in module os)}
  29 \begin{datadesc}{name}
  30 The name of the OS dependent module imported, e.g. \code{'posix'} or
  31 \code{'mac'}.
  32 \end{datadesc}
  33
  34 \begin{datadesc}{path}
  35 The corresponding OS dependent standard module for pathname
  36 operations, e.g., \code{posixpath} or \code{macpath}.  Thus, (given
  37 the proper imports), \code{os.path.split(\var{file})} is equivalent to but
  38 more portable than \code{posixpath.split(\var{file})}.
  39 \end{datadesc}
  40
  41 \begin{datadesc}{curdir}
  42 The constant string used by the OS to refer to the current directory,
  43 e.g. \code{'.'} for POSIX or \code{':'} for the Mac.
  44 \end{datadesc}
  45
  46 \begin{datadesc}{pardir}
  47 The constant string used by the OS to refer to the parent directory,
  48 e.g. \code{'..'} for POSIX or \code{'::'} for the Mac.
  49 \end{datadesc}
  50
  51 \begin{datadesc}{sep}
  52 The character used by the OS to separate pathname components, e.g.
  53 \code{'/'} for POSIX or \code{':'} for the Mac.  Note that knowing this
  54 is not sufficient to be able to parse or concatenate pathnames---better
  55 use \code{os.path.split()} and \code{os.path.join()}---but it is
  56 occasionally useful.
  57 \end{datadesc}
  58
  59 \begin{funcdesc}{execl}{path\, arg0\, arg1\, ...}
  60 This is equivalent to a call to \code{os.execv} with an \var{argv}
  61 of \code{[\var{arg0}, \var{arg1}, ...]}.
  62 \end{funcdesc}
  63
  64 \begin{funcdesc}{execle}{path\, arg0\, arg1\, ...\, env}
  65 This is equivalent to a call to \code{os.execve} with an \var{argv}
  66 of \code{[\var{arg0}, \var{arg1}, ...]}.
  67 \end{funcdesc}
  68
  69 \begin{funcdesc}{execlp}{path\, arg0\, arg1\, ...}
  70 This is like \code{execl} but duplicates the shell's actions in
  71 searching for an executable file in a list of directories.  The
  72 directory list is obtained from \code{environ['PATH']}.
  73 \end{funcdesc}
  74
  75 \begin{funcdesc}{execvp}{path\, arg0\, arg1\, ...}
  76 \code{execvp} is for \code{execv} what \code{execlp} is for \code{execl}.
  77 \end{funcdesc}