diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/lib/libposix.tex | 18 | ||||
| -rw-r--r-- | Doc/libposix.tex | 18 |
2 files changed, 28 insertions, 8 deletions
diff --git a/Doc/lib/libposix.tex b/Doc/lib/libposix.tex index e545c7a..97756c7 100644 --- a/Doc/lib/libposix.tex +++ b/Doc/lib/libposix.tex @@ -13,7 +13,9 @@ the \code{posix} interface. On non-\UNIX{} operating systems the \code{posix} module is not available, but a subset is always available through the \code{os} interface. Once \code{os} is imported, there is \emph{no} performance penalty in using it instead of -\code{posix}. +\code{posix}. In addition, \code{os} provides some additional +functionality, such as automatically calling \code{putenv()} +when an entry is \code{os.environ} is changed. \stmodindex{os} The descriptions below are very terse; refer to the @@ -35,13 +37,17 @@ For example, is the pathname of your home directory, equivalent to \code{getenv("HOME")} in C. + Modifying this dictionary does not affect the string environment passed on by \code{execv()}, \code{popen()} or \code{system()}; if you need to change the environment, pass \code{environ} to \code{execve()} or add variable assignments and export statements to the command -string for \code{system()} or \code{popen()}.% -\footnote{The problem with automatically passing on \code{environ} is -that there is no portable way of changing the environment.} +string for \code{system()} or \code{popen()}. + +\emph{However:} If you are using this module via the \code{os} module +(as you should -- see the introduction above), \code{environ} is a +a mapping object that behaves almost like a dictionary but invokes +\code{putenv()} automatically called whenever an item is changed. \end{datadesc} \renewcommand{\indexsubitem}{(exception in module posix)} @@ -238,6 +244,10 @@ The default \var{mode} is 0777 (octal), and the current umask value is first masked out. Return the file descriptor for the newly opened file. +For a description of the flag and mode values, see the \UNIX{} or C +run-time documentation; flag constants (like \code{O_RDONLY} and +\code{O_WRONLY}) are defined in this module too (see below). + Note: this function is intended for low-level I/O. For normal usage, use the built-in function \code{open}, which returns a ``file object'' with \code{read()} and \code{write()} methods (and many more). diff --git a/Doc/libposix.tex b/Doc/libposix.tex index e545c7a..97756c7 100644 --- a/Doc/libposix.tex +++ b/Doc/libposix.tex @@ -13,7 +13,9 @@ the \code{posix} interface. On non-\UNIX{} operating systems the \code{posix} module is not available, but a subset is always available through the \code{os} interface. Once \code{os} is imported, there is \emph{no} performance penalty in using it instead of -\code{posix}. +\code{posix}. In addition, \code{os} provides some additional +functionality, such as automatically calling \code{putenv()} +when an entry is \code{os.environ} is changed. \stmodindex{os} The descriptions below are very terse; refer to the @@ -35,13 +37,17 @@ For example, is the pathname of your home directory, equivalent to \code{getenv("HOME")} in C. + Modifying this dictionary does not affect the string environment passed on by \code{execv()}, \code{popen()} or \code{system()}; if you need to change the environment, pass \code{environ} to \code{execve()} or add variable assignments and export statements to the command -string for \code{system()} or \code{popen()}.% -\footnote{The problem with automatically passing on \code{environ} is -that there is no portable way of changing the environment.} +string for \code{system()} or \code{popen()}. + +\emph{However:} If you are using this module via the \code{os} module +(as you should -- see the introduction above), \code{environ} is a +a mapping object that behaves almost like a dictionary but invokes +\code{putenv()} automatically called whenever an item is changed. \end{datadesc} \renewcommand{\indexsubitem}{(exception in module posix)} @@ -238,6 +244,10 @@ The default \var{mode} is 0777 (octal), and the current umask value is first masked out. Return the file descriptor for the newly opened file. +For a description of the flag and mode values, see the \UNIX{} or C +run-time documentation; flag constants (like \code{O_RDONLY} and +\code{O_WRONLY}) are defined in this module too (see below). + Note: this function is intended for low-level I/O. For normal usage, use the built-in function \code{open}, which returns a ``file object'' with \code{read()} and \code{write()} methods (and many more). |