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More emphasis on os.environ's calling of putenv; and added hint about

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flags for open().
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Guido van Rossum 1997-08-08 21:05:09 +00:00
parent 7d6b7d3f54
commit 9c43c590bc
2 changed files with 28 additions and 8 deletions
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18
Doc/lib/libposix.tex
View file

@ -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 \code{posix} module is not available, but a subset is always available
through the \code{os} interface. Once \code{os} is imported, there is through the \code{os} interface. Once \code{os} is imported, there is
\emph{no} performance penalty in using it instead of \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} \stmodindex{os}
The descriptions below are very terse; refer to the The descriptions below are very terse; refer to the
@ -35,13 +37,17 @@ For example,
is the pathname of your home directory, equivalent to is the pathname of your home directory, equivalent to
\code{getenv("HOME")} \code{getenv("HOME")}
in C. in C.
Modifying this dictionary does not affect the string environment Modifying this dictionary does not affect the string environment
passed on by \code{execv()}, \code{popen()} or \code{system()}; if you passed on by \code{execv()}, \code{popen()} or \code{system()}; if you
need to change the environment, pass \code{environ} to \code{execve()} need to change the environment, pass \code{environ} to \code{execve()}
or add variable assignments and export statements to the command or add variable assignments and export statements to the command
string for \code{system()} or \code{popen()}.% 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.} \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} \end{datadesc}
\renewcommand{\indexsubitem}{(exception in module posix)} \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 first masked out. Return the file descriptor for the newly opened
file. 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, 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'' use the built-in function \code{open}, which returns a ``file object''
with \code{read()} and \code{write()} methods (and many more). with \code{read()} and \code{write()} methods (and many more).

18
Doc/libposix.tex
View file

@ -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 \code{posix} module is not available, but a subset is always available
through the \code{os} interface. Once \code{os} is imported, there is through the \code{os} interface. Once \code{os} is imported, there is
\emph{no} performance penalty in using it instead of \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} \stmodindex{os}
The descriptions below are very terse; refer to the The descriptions below are very terse; refer to the
@ -35,13 +37,17 @@ For example,
is the pathname of your home directory, equivalent to is the pathname of your home directory, equivalent to
\code{getenv("HOME")} \code{getenv("HOME")}
in C. in C.
Modifying this dictionary does not affect the string environment Modifying this dictionary does not affect the string environment
passed on by \code{execv()}, \code{popen()} or \code{system()}; if you passed on by \code{execv()}, \code{popen()} or \code{system()}; if you
need to change the environment, pass \code{environ} to \code{execve()} need to change the environment, pass \code{environ} to \code{execve()}
or add variable assignments and export statements to the command or add variable assignments and export statements to the command
string for \code{system()} or \code{popen()}.% 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.} \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} \end{datadesc}
\renewcommand{\indexsubitem}{(exception in module posix)} \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 first masked out. Return the file descriptor for the newly opened
file. 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, 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'' use the built-in function \code{open}, which returns a ``file object''
with \code{read()} and \code{write()} methods (and many more). with \code{read()} and \code{write()} methods (and many more).