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author | Fred Drake <fdrake@acm.org> | 1998-03-11 05:29:58 (GMT) |
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committer | Fred Drake <fdrake@acm.org> | 1998-03-11 05:29:58 (GMT) |
commit | 75aae9ad893003f5793a75991f854ad6c69fcd07 (patch) | |
tree | 56d8bbc74c839017cd8e8a933ea8ccfbd71803c6 /Doc/lib/libposix.tex | |
parent | e2e904f303cb5f6b1912b5f45f551298746d754c (diff) | |
download | cpython-75aae9ad893003f5793a75991f854ad6c69fcd07.zip cpython-75aae9ad893003f5793a75991f854ad6c69fcd07.tar.gz cpython-75aae9ad893003f5793a75991f854ad6c69fcd07.tar.bz2 |
Logical markup.
Added information on the exception attributes when exceptions are classes.
Diffstat (limited to 'Doc/lib/libposix.tex')
-rw-r--r-- | Doc/lib/libposix.tex | 263 |
1 files changed, 140 insertions, 123 deletions
diff --git a/Doc/lib/libposix.tex b/Doc/lib/libposix.tex index fa05aca..1a62bba 100644 --- a/Doc/lib/libposix.tex +++ b/Doc/lib/libposix.tex @@ -3,19 +3,19 @@ \bimodindex{posix} This module provides access to operating system functionality that is -standardized by the C Standard and the \POSIX{} standard (a thinly disguised -\UNIX{} interface). +standardized by the \C{} Standard and the \POSIX{} standard (a thinly +disguised \UNIX{} interface). \strong{Do not import this module directly.} Instead, import the -module \code{os}, which provides a \emph{portable} version of this -interface. On \UNIX{}, the \code{os} module provides a superset of -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}. In addition, \code{os} provides some additional -functionality, such as automatically calling \code{putenv()} -when an entry is \code{os.environ} is changed. +module \module{os}, which provides a \emph{portable} version of this +interface. On \UNIX{}, the \module{os} module provides a superset of +the \module{posix} interface. On non-\UNIX{} operating systems the +\module{posix} module is not available, but a subset is always +available through the \module{os} interface. Once \module{os} is +imported, there is \emph{no} performance penalty in using it instead +of \module{posix}. In addition, \module{os} provides some additional +functionality, such as automatically calling \function{putenv()} +when an entry in \code{os.environ} is changed. \refstmodindex{os} The descriptions below are very terse; refer to the corresponding @@ -24,9 +24,9 @@ Arguments called \var{path} refer to a pathname given as a string. Errors are reported as exceptions; the usual exceptions are given for type errors, while errors reported by the system calls raise -\code{posix.error}, described below. +\exception{error}, described below. -Module \code{posix} defines the following data items: +Module \module{posix} defines the following data items: \setindexsubitem{(data in module posix)} \begin{datadesc}{environ} @@ -36,30 +36,40 @@ For example, \code{posix.environ['HOME']} is the pathname of your home directory, equivalent to \code{getenv("HOME")} -in C. +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()}. - -\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. +passed on by \function{execv()}, \function{popen()} or +\function{system()}; if you need to change the environment, pass +\code{environ} to \function{execve()} or add variable assignments and +export statements to the command string for \function{system()} or +\function{popen()}. + +\emph{However:} If you are using this module via the \module{os} +module (as you should -- see the introduction above), \code{environ} +is a a mapping object that behaves almost like a dictionary but +invokes \function{putenv()} automatically called whenever an item is +changed. \end{datadesc} \setindexsubitem{(exception in module posix)} \begin{excdesc}{error} This exception is raised when a \POSIX{} function returns a -\POSIX{}-related error (e.g., not for illegal argument types). Its -string value is \code{'posix.error'}. The accompanying value is a -pair containing the numeric error code from \code{errno} and the -corresponding string, as would be printed by the C function -\code{perror()}. -See the module \module{errno}\refbimodindex{errno}, which contains -names for the error codes defined by the underlying operating system. +\POSIX{}-related error (e.g., not for illegal argument types). The +accompanying value is a pair containing the numeric error code from +\cdata{errno} and the corresponding string, as would be printed by the +\C{} function \cfunction{perror()}. See the module +\module{errno}\refbimodindex{errno}, which contains names for the +error codes defined by the underlying operating system. + +When exceptions are classes, this exception carries two attributes, +\member{errno} and \member{strerror}. The first holds the value of +the \C{} \cdata{errno} variable, and the latter holds the +corresponding error message from \cfunction{strerror()}. + +When exceptions are strings, the string for the exception is +\code{'os.error'}; this reflects the more portable access to the +exception through the \module{os} module. \end{excdesc} It defines the following functions and constants: @@ -83,10 +93,10 @@ and \var{gid}. Close file descriptor \var{fd}. Note: this function is intended for low-level I/O and must be applied -to a file descriptor as returned by \code{posix.open()} or -\code{posix.pipe()}. To close a ``file object'' returned by the -built-in function \code{open} or by \code{posix.popen} or -\code{posix.fdopen}, use its \code{close()} method. +to a file descriptor as returned by \function{open()} or +\function{pipe()}. To close a ``file object'' returned by the +built-in function \function{open()} or by \function{popen()} or +\function{fdopen()}, use its \method{close()} method. \end{funcdesc} \begin{funcdesc}{dup}{fd} @@ -95,7 +105,7 @@ Return a duplicate of file descriptor \var{fd}. \begin{funcdesc}{dup2}{fd\, fd2} Duplicate file descriptor \var{fd} to \var{fd2}, closing the latter -first if necessary. Return \code{None}. +first if necessary. \end{funcdesc} \begin{funcdesc}{execv}{path\, args} @@ -120,24 +130,24 @@ handlers, flushing stdio buffers, etc. (Not on MS-DOS.) Note: the standard way to exit is \code{sys.exit(\var{n})}. -\code{posix._exit()} should normally only be used in the child process -after a \code{fork()}. +\function{_exit()} should normally only be used in the child process +after a \function{fork()}. \end{funcdesc} \begin{funcdesc}{fdopen}{fd\optional{\, mode\optional{\, bufsize}}} Return an open file object connected to the file descriptor \var{fd}. The \var{mode} and \var{bufsize} arguments have the same meaning as -the corresponding arguments to the built-in \code{open()} function. +the corresponding arguments to the built-in \function{open()} function. \end{funcdesc} \begin{funcdesc}{fork}{} -Fork a child process. Return 0 in the child, the child's process id -in the parent. +Fork a child process. Return \code{0} in the child, the child's +process id in the parent. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{fstat}{fd} -Return status for file descriptor \var{fd}, like \code{stat()}. +Return status for file descriptor \var{fd}, like \function{stat()}. \end{funcdesc} \begin{funcdesc}{ftruncate}{fd\, length} @@ -203,61 +213,63 @@ directory. \begin{funcdesc}{lseek}{fd\, pos\, how} Set the current position of file descriptor \var{fd} to position -\var{pos}, modified by \var{how}: 0 to set the position relative to -the beginning of the file; 1 to set it relative to the current -position; 2 to set it relative to the end of the file. +\var{pos}, modified by \var{how}: \code{0} to set the position +relative to the beginning of the file; \code{1} to set it relative to +the current position; \code{2} to set it relative to the end of the +file. \end{funcdesc} \begin{funcdesc}{lstat}{path} -Like \code{stat()}, but do not follow symbolic links. (On systems -without symbolic links, this is identical to \code{posix.stat()}.) +Like \function{stat()}, but do not follow symbolic links. (On systems +without symbolic links, this is identical to \function{stat()}.) \end{funcdesc} \begin{funcdesc}{mkfifo}{path\optional{\, mode}} Create a FIFO (a \POSIX{} named pipe) named \var{path} with numeric mode -\var{mode}. The default \var{mode} is 0666 (octal). The current +\var{mode}. The default \var{mode} is \code{0666} (octal). The current umask value is first masked out from the mode. (Not on MS-DOS.) FIFOs are pipes that can be accessed like regular files. FIFOs exist -until they are deleted (for example with \code{os.unlink}). -Generally, FIFOs are used as rendez-vous between ``client'' and +until they are deleted (for example with \function{os.unlink()}). +Generally, FIFOs are used as rendezvous between ``client'' and ``server'' type processes: the server opens the FIFO for reading, and -the client opens it for writing. Note that \code{mkfifo()} doesn't -open the FIFO -- it just creates the rendez-vous point. +the client opens it for writing. Note that \function{mkfifo()} +doesn't open the FIFO --- it just creates the rendezvous point. \end{funcdesc} \begin{funcdesc}{mkdir}{path\optional{\, mode}} Create a directory named \var{path} with numeric mode \var{mode}. -The default \var{mode} is 0777 (octal). On some systems, \var{mode} -is ignored. Where it is used, the current umask value is first -masked out. +The default \var{mode} is \code{0777} (octal). On some systems, +\var{mode} is ignored. Where it is used, the current umask value is +first masked out. \end{funcdesc} \begin{funcdesc}{nice}{increment} -Add \var{incr} to the process' ``niceness''. Return the new niceness. -(Not on MS-DOS.) +Add \var{increment} to the process' ``niceness''. Return the new +niceness. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{open}{file\, flags\optional{\, mode}} Open the file \var{file} and set various flags according to \var{flags} and possibly its mode according to \var{mode}. -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. +The default \var{mode} is \code{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). +For a description of the flag and mode values, see the \UNIX{} or \C{} +run-time documentation; flag constants (like \constant{O_RDONLY} and +\constant{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). +use the built-in function \function{open()}, which returns a ``file +object'' with \method{read()} and \method{write()} methods (and many +more). \end{funcdesc} \begin{funcdesc}{pipe}{} -Create a pipe. Return a pair of file descriptors \code{(r, w)} -usable for reading and writing, respectively. +Create a pipe. Return a pair of file descriptors \code{(\var{r}, +\var{w})} usable for reading and writing, respectively. (Not on MS-DOS.) \end{funcdesc} @@ -272,23 +284,23 @@ Open a pipe to or from \var{command}. The return value is an open file object connected to the pipe, which can be read or written depending on whether \var{mode} is \code{'r'} (default) or \code{'w'}. The \var{bufsize} argument has the same meaning as the corresponding -argument to the built-in \code{open()} function. The exit status of -the command (encoded in the format specified for \code{wait()}) is -available as the return value of the \code{close()} method of the file +argument to the built-in \function{open()} function. The exit status of +the command (encoded in the format specified for \function{wait()}) is +available as the return value of the \method{close()} method of the file object. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{putenv}{varname\, value} -Set the environment variable named \var{varname} to the string \var{value}. -Such changes to the environment affect -subprocesses started with \code{os.system()}, \code{os.popen()} or -\code{os.fork()} and \code{os.execv()}. (Not on all systems.) +Set the environment variable named \var{varname} to the string +\var{value}. Such changes to the environment affect subprocesses +started with \function{os.system()}, \function{os.popen()} or +\function{os.fork()} and \function{os.execv()}. (Not on all systems.) -When \code{putenv()} is +When \function{putenv()} is supported, assignments to items in \code{os.environ} are automatically -translated into corresponding calls to \code{os.putenv()}; however, -calls to \code{os.putenv()} don't update \code{os.environ}, so it is +translated into corresponding calls to \function{putenv()}; however, +calls to \function{putenv()} don't update \code{os.environ}, so it is actually preferable to assign to items of \code{os.environ}. \end{funcdesc} @@ -301,22 +313,23 @@ Read at most \var{n} bytes from file descriptor \var{fd}. Return a string containing the bytes read. Note: this function is intended for low-level I/O and must be applied -to a file descriptor as returned by \code{posix.open()} or -\code{posix.pipe()}. To read a ``file object'' returned by the -built-in function \code{open} or by \code{posix.popen} or -\code{posix.fdopen}, or \code{sys.stdin}, use its -\code{read()} or \code{readline()} methods. +to a file descriptor as returned by \function{open()} or +\function{pipe()}. To read a ``file object'' returned by the +built-in function \function{open()} or by \function{popen()} or +\function{fdopen()}, or \code{sys.stdin}, use its +\method{read()} or \method{readline()} methods. \end{funcdesc} \begin{funcdesc}{readlink}{path} Return a string representing the path to which the symbolic link points. (On systems without symbolic links, this always raises -\code{posix.error}.) +\exception{error}.) \end{funcdesc} \begin{funcdesc}{remove}{path} -Remove the file \var{path}. See \code{rmdir} below to remove a directory. -This is identical to the \code{unlink} function documented below. +Remove the file \var{path}. See \function{rmdir()} below to remove a +directory. This is identical to the \function{unlink()} function +documented below. \end{funcdesc} \begin{funcdesc}{rename}{src\, dst} @@ -333,21 +346,21 @@ Set the current process' group id. \end{funcdesc} \begin{funcdesc}{setpgrp}{} -Calls the system call \code{setpgrp()} or \code{setpgrp(0, 0)} -depending on which version is implemented (if any). See the \UNIX{} -manual for the semantics. +Calls the system call \cfunction{setpgrp()} or \cfunction{setpgrp(0, +0)} depending on which version is implemented (if any). See the +\UNIX{} manual for the semantics. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{setpgid}{pid\, pgrp} -Calls the system call \code{setpgid()}. See the \UNIX{} manual for -the semantics. +Calls the system call \cfunction{setpgid()}. See the \UNIX{} manual +for the semantics. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{setsid}{} -Calls the system call \code{setsid()}. See the \UNIX{} manual for the -semantics. +Calls the system call \cfunction{setsid()}. See the \UNIX{} manual +for the semantics. (Not on MS-DOS.) \end{funcdesc} @@ -357,9 +370,10 @@ Set the current process' user id. \end{funcdesc} \begin{funcdesc}{stat}{path} -Perform a \emph{stat} system call on the given path. The return value -is a tuple of at least 10 integers giving the most important (and -portable) members of the \emph{stat} structure, in the order +Perform a \cfunction{stat()} system call on the given path. The +return value is a tuple of at least 10 integers giving the most +important (and portable) members of the \emph{stat} structure, in the +order \code{st_mode}, \code{st_ino}, \code{st_dev}, @@ -373,35 +387,34 @@ portable) members of the \emph{stat} structure, in the order More items may be added at the end by some implementations. (On MS-DOS, some items are filled with dummy values.) -Note: The standard module \code{stat} defines functions and constants -that are useful for extracting information from a stat structure. -\refstmodindex{stat} +Note: The standard module \module{stat}\refstmodindex{stat} defines +functions and constants that are useful for extracting information +from a stat structure. \end{funcdesc} \begin{funcdesc}{symlink}{src\, dst} Create a symbolic link pointing to \var{src} named \var{dst}. (On -systems without symbolic links, this always raises -\code{posix.error}.) +systems without symbolic links, this always raises \exception{error}.) \end{funcdesc} \begin{funcdesc}{system}{command} Execute the command (a string) in a subshell. This is implemented by -calling the Standard C function \code{system()}, and has the same -limitations. Changes to \code{posix.environ}, \code{sys.stdin} etc.\ are -not reflected in the environment of the executed command. The return -value is the exit status of the process encoded in the format -specified for \code{wait()}. +calling the Standard \C{} function \cfunction{system()}, and has the +same limitations. Changes to \code{posix.environ}, \code{sys.stdin} +etc.\ are not reflected in the environment of the executed command. +The return value is the exit status of the process encoded in the +format specified for \function{wait()}. \end{funcdesc} \begin{funcdesc}{tcgetpgrp}{fd} Return the process group associated with the terminal given by -\var{fd} (an open file descriptor as returned by \code{posix.open()}). +\var{fd} (an open file descriptor as returned by \function{open()}). (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{tcsetpgrp}{fd\, pg} Set the process group associated with the terminal given by -\var{fd} (an open file descriptor as returned by \code{posix.open()}) +\var{fd} (an open file descriptor as returned by \function{open()}) to \var{pg}. (Not on MS-DOS.) \end{funcdesc} @@ -412,7 +425,7 @@ or other) times, in seconds. The items are: user time, system time, children's user time, children's system time, and elapsed real time since a fixed point in the past, in that order. See the \UNIX{} -manual page \emph{times}(2). (Not on MS-DOS.) +manual page \manpage{times}{2}. (Not on MS-DOS.) \end{funcdesc} \begin{funcdesc}{umask}{mask} @@ -423,11 +436,14 @@ Set the current numeric umask and returns the previous umask. \begin{funcdesc}{uname}{} Return a 5-tuple containing information identifying the current operating system. The tuple contains 5 strings: -\code{(\var{sysname}, \var{nodename}, \var{release}, \var{version}, \var{machine})}. -Some systems truncate the nodename to 8 +\code{(\var{sysname}, \var{nodename}, \var{release}, \var{version}, +\var{machine})}. Some systems truncate the nodename to 8 characters or to the leading component; a better way to get the -hostname is \code{socket.gethostname()} or even -\code{socket.gethostbyaddr(socket.gethostname())}. +hostname is \function{socket.gethostname()}% +\index{gethostname()@\idxcode{gethostname()} (in module socket)} +or even +\code{socket.gethostbyaddr(socket.gethostname())}% +\index{gethostbyaddr()@\idxcode{gethostbyaddr()} (in module socket)}. (Not on MS-DOS, nor on older \UNIX{} systems.) \end{funcdesc} @@ -452,10 +468,11 @@ byte is set if a core file was produced. (Not on MS-DOS.) \begin{funcdesc}{waitpid}{pid\, options} Wait for completion of a child process given by proces id, and return a tuple containing its pid and exit status indication (encoded as for -\code{wait()}). The semantics of the call are affected by the value of -the integer options, which should be 0 for normal operation. (If the -system does not support \code{waitpid()}, this always raises -\code{posix.error}. Not on MS-DOS.) +\function{wait()}). The semantics of the call are affected by the +value of the integer \var{options}, which should be \code{0} for +normal operation. (If the system does not support +\function{waitpid()}, this always raises \exception{error}. Not on +MS-DOS.) \end{funcdesc} \begin{funcdesc}{write}{fd\, str} @@ -463,16 +480,16 @@ Write the string \var{str} to file descriptor \var{fd}. Return the number of bytes actually written. Note: this function is intended for low-level I/O and must be applied -to a file descriptor as returned by \code{posix.open()} or -\code{posix.pipe()}. To write a ``file object'' returned by the -built-in function \code{open} or by \code{posix.popen} or -\code{posix.fdopen}, or \code{sys.stdout} or \code{sys.stderr}, use -its \code{write()} method. +to a file descriptor as returned by \function{open()} or +\function{pipe()}. To write a ``file object'' returned by the +built-in function \function{open()} or by \function{popen()} or +\function{fdopen()}, or \code{sys.stdout} or \code{sys.stderr}, use +its \method{write()} method. \end{funcdesc} \begin{datadesc}{WNOHANG} -The option for \code{waitpid()} to avoid hanging if no child process -status is available immediately. +The option for \function{waitpid()} to avoid hanging if no child +process status is available immediately. \end{datadesc} @@ -489,6 +506,6 @@ status is available immediately. \dataline{O_CREAT} \dataline{O_EXCL} \dataline{O_TRUNC} -Options for the \code{flag} argument to the \code{open()} function. +Options for the \code{flag} argument to the \function{open()} function. These can be bit-wise OR'd together. \end{datadesc} |