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Document return value of wait[pid]() more carefully.

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Document how to get exit status of a popen() command.
This commit is contained in:
Guido van Rossum 1997-05-09 02:22:59 +00:00
parent e4f347e779
commit 7e691de948
2 changed files with 24 additions and 14 deletions
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19
Doc/lib/libposix.tex
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@ -254,7 +254,10 @@ 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 file object connected to the pipe, which can be read or written
depending on whether \var{mode} is \code{'r'} (default) or \code{'w'}. depending on whether \var{mode} is \code{'r'} (default) or \code{'w'}.
The \var{bufsize} argument has the same meaning as the corresponding The \var{bufsize} argument has the same meaning as the corresponding
argument to the built-in \code{open()} function. 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
object.
(Not on MS-DOS.) (Not on MS-DOS.)
\end{funcdesc} \end{funcdesc}
@ -349,8 +352,8 @@ Execute the command (a string) in a subshell. This is implemented by
calling the Standard C function \code{system()}, and has the same calling the Standard C function \code{system()}, and has the same
limitations. Changes to \code{posix.environ}, \code{sys.stdin} etc.\ are limitations. Changes to \code{posix.environ}, \code{sys.stdin} etc.\ are
not reflected in the environment of the executed command. The return not reflected in the environment of the executed command. The return
value is the exit status of the process as returned by Standard C value is the exit status of the process encoded in the format
\code{system()}. specified for \code{wait()}.
\end{funcdesc} \end{funcdesc}
\begin{funcdesc}{tcgetpgrp}{fd} \begin{funcdesc}{tcgetpgrp}{fd}
@ -402,14 +405,16 @@ Set the access and modified time of the file to the given values.
\begin{funcdesc}{wait}{} \begin{funcdesc}{wait}{}
Wait for completion of a child process, and return a tuple containing Wait for completion of a child process, and return a tuple containing
its pid and exit status indication (encoded as by \UNIX{}). its pid and exit status indication: a 16-bit number, whose low byte is
(Not on MS-DOS.) the signal number that killed the process, and whose high byte is the
exit status (if the signal number is zero); the high bit of the low
byte is set if a core file was produced. (Not on MS-DOS.)
\end{funcdesc} \end{funcdesc}
\begin{funcdesc}{waitpid}{pid\, options} \begin{funcdesc}{waitpid}{pid\, options}
Wait for completion of a child process given by proces id, and return Wait for completion of a child process given by proces id, and return
a tuple containing its pid and exit status indication (encoded as by a tuple containing its pid and exit status indication (encoded as for
\UNIX{}). The semantics of the call are affected by the value of \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 the integer options, which should be 0 for normal operation. (If the
system does not support \code{waitpid()}, this always raises system does not support \code{waitpid()}, this always raises
\code{posix.error}. Not on MS-DOS.) \code{posix.error}. Not on MS-DOS.)

19
Doc/libposix.tex
View File

@ -254,7 +254,10 @@ 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 file object connected to the pipe, which can be read or written
depending on whether \var{mode} is \code{'r'} (default) or \code{'w'}. depending on whether \var{mode} is \code{'r'} (default) or \code{'w'}.
The \var{bufsize} argument has the same meaning as the corresponding The \var{bufsize} argument has the same meaning as the corresponding
argument to the built-in \code{open()} function. 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
object.
(Not on MS-DOS.) (Not on MS-DOS.)
\end{funcdesc} \end{funcdesc}
@ -349,8 +352,8 @@ Execute the command (a string) in a subshell. This is implemented by
calling the Standard C function \code{system()}, and has the same calling the Standard C function \code{system()}, and has the same
limitations. Changes to \code{posix.environ}, \code{sys.stdin} etc.\ are limitations. Changes to \code{posix.environ}, \code{sys.stdin} etc.\ are
not reflected in the environment of the executed command. The return not reflected in the environment of the executed command. The return
value is the exit status of the process as returned by Standard C value is the exit status of the process encoded in the format
\code{system()}. specified for \code{wait()}.
\end{funcdesc} \end{funcdesc}
\begin{funcdesc}{tcgetpgrp}{fd} \begin{funcdesc}{tcgetpgrp}{fd}
@ -402,14 +405,16 @@ Set the access and modified time of the file to the given values.
\begin{funcdesc}{wait}{} \begin{funcdesc}{wait}{}
Wait for completion of a child process, and return a tuple containing Wait for completion of a child process, and return a tuple containing
its pid and exit status indication (encoded as by \UNIX{}). its pid and exit status indication: a 16-bit number, whose low byte is
(Not on MS-DOS.) the signal number that killed the process, and whose high byte is the
exit status (if the signal number is zero); the high bit of the low
byte is set if a core file was produced. (Not on MS-DOS.)
\end{funcdesc} \end{funcdesc}
\begin{funcdesc}{waitpid}{pid\, options} \begin{funcdesc}{waitpid}{pid\, options}
Wait for completion of a child process given by proces id, and return Wait for completion of a child process given by proces id, and return
a tuple containing its pid and exit status indication (encoded as by a tuple containing its pid and exit status indication (encoded as for
\UNIX{}). The semantics of the call are affected by the value of \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 the integer options, which should be 0 for normal operation. (If the
system does not support \code{waitpid()}, this always raises system does not support \code{waitpid()}, this always raises
\code{posix.error}. Not on MS-DOS.) \code{posix.error}. Not on MS-DOS.)