653 lines
17 KiB
HTML
653 lines
17 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of PYTHON</TITLE>
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</HEAD><BODY>
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<H1>PYTHON</H1>
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Section: User Commands (1)<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<P>
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<P>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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python - an interpreted, interactive, object-oriented programming language
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>python</B>
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[
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<B>-B</B>
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]
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[
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<B>-d</B>
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]
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[
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<B>-E</B>
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]
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[
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<B>-h</B>
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]
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[
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<B>-i</B>
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]
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[
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<B>-m </B>
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<I>module-name</I>
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]
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<BR>
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<BR> [
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<B>-O</B>
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]
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[
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<B>-OO</B>
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]
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[
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<B>-R</B>
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]
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[
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<B>-Q</B>
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<I>argument</I>
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]
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[
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<B>-s</B>
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]
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[
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<B>-S</B>
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]
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[
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<B>-t</B>
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]
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[
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<B>-u</B>
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]
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<BR>
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<BR> [
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<B>-v</B>
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]
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[
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<B>-V</B>
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]
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[
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<B>-W</B>
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<I>argument</I>
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]
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[
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<B>-x</B>
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]
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[
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<B>-3</B>
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]
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[
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<B>-?</B>
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]
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<BR>
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<BR> [
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<B>-c</B>
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<I>command</I>
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<I>script</I>
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-
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]
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[
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<I>arguments</I>
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]
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Python is an interpreted, interactive, object-oriented programming
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language that combines remarkable power with very clear syntax.
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For an introduction to programming in Python, see the Python Tutorial.
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The Python Library Reference documents built-in and standard types,
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constants, functions and modules.
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Finally, the Python Reference Manual describes the syntax and
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semantics of the core language in (perhaps too) much detail.
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(These documents may be located via the
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<B>INTERNET RESOURCES</B>
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below; they may be installed on your system as well.)
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<P>
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Python's basic power can be extended with your own modules written in
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C or C++.
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On most systems such modules may be dynamically loaded.
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Python is also adaptable as an extension language for existing
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applications.
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See the internal documentation for hints.
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<P>
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Documentation for installed Python modules and packages can be
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viewed by running the
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<B>pydoc</B>
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program.
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<A NAME="lbAE"> </A>
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<H2>COMMAND LINE OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><B>-B</B>
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<DD>
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Don't write
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<I>.py[co]</I>
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files on import. See also PYTHONDONTWRITEBYTECODE.
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<DT id="2"><B>-c </B><I>command</I>
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<DD>
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Specify the command to execute (see next section).
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This terminates the option list (following options are passed as
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arguments to the command).
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<DT id="3"><B>-d</B>
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<DD>
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Turn on parser debugging output (for wizards only, depending on
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compilation options).
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<DT id="4"><B>-E</B>
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<DD>
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Ignore environment variables like PYTHONPATH and PYTHONHOME that modify
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the behavior of the interpreter.
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<DT id="5"><B>-h , -? , --help</B>
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<DD>
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Prints the usage for the interpreter executable and exits.
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<DT id="6"><B>-i</B>
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<DD>
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When a script is passed as first argument or the <B>-c</B> option is
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used, enter interactive mode after executing the script or the
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command. It does not read the $PYTHONSTARTUP file. This can be
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useful to inspect global variables or a stack trace when a script
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raises an exception.
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<DT id="7"><B>-m </B><I>module-name</I>
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<DD>
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Searches
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<I>sys.path </I>
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for the named module and runs the corresponding
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<I>.py </I>
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file as a script.
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<DT id="8"><B>-O</B>
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<DD>
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Turn on basic optimizations. This changes the filename extension for
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compiled (bytecode) files from
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<I>.pyc</I>
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to <I>.pyo</I>. Given twice, causes docstrings to be discarded.
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<DT id="9"><B>-OO</B>
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<DD>
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Discard docstrings in addition to the <B>-O</B> optimizations.
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<DT id="10"><B>-R</B>
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<DD>
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Turn on "hash randomization", so that the hash() values of str, bytes and
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datetime objects are "salted" with an unpredictable pseudo-random value.
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Although they remain constant within an individual Python process, they are
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not predictable between repeated invocations of Python.
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<DT id="11"><DD>
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This is intended to provide protection against a denial of service
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caused by carefully-chosen inputs that exploit the worst case performance
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of a dict construction, O(n^2) complexity. See
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<A HREF="http://www.ocert.org/advisories/ocert-2011-003.html">http://www.ocert.org/advisories/ocert-2011-003.html</A>
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for details.
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<DT id="12"><B>-Q </B><I>argument</I>
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<DD>
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Division control; see PEP 238. The argument must be one of "old" (the
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default, int/int and long/long return an int or long), "new" (new
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division semantics, i.e. int/int and long/long returns a float),
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"warn" (old division semantics with a warning for int/int and
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long/long), or "warnall" (old division semantics with a warning for
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all use of the division operator). For a use of "warnall", see the
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Tools/scripts/fixdiv.py script.
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<DT id="13"><B>-s</B>
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<DD>
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Don't add user site directory to sys.path.
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<DT id="14"><B>-S</B>
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<DD>
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Disable the import of the module
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<I>site</I>
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and the site-dependent manipulations of
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<I>sys.path</I>
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that it entails.
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<DT id="15"><B>-t</B>
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<DD>
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Issue a warning when a source file mixes tabs and spaces for
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indentation in a way that makes it depend on the worth of a tab
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expressed in spaces. Issue an error when the option is given twice.
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<DT id="16"><B>-u</B>
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<DD>
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Force stdin, stdout and stderr to be totally unbuffered. On systems
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where it matters, also put stdin, stdout and stderr in binary mode.
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Note that there is internal buffering in xreadlines(), readlines() and
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file-object iterators ("for line in sys.stdin") which is not
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influenced by this option. To work around this, you will want to use
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"sys.stdin.readline()" inside a "while 1:" loop.
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<DT id="17"><B>-v</B>
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<DD>
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Print a message each time a module is initialized, showing the place
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(filename or built-in module) from which it is loaded. When given
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twice, print a message for each file that is checked for when
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searching for a module. Also provides information on module cleanup
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at exit.
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<DT id="18"><B>-V , --version</B>
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<DD>
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Prints the Python version number of the executable and exits.
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<DT id="19"><B>-W </B><I>argument</I>
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<DD>
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Warning control. Python sometimes prints warning message to
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<I>sys.stderr</I>.
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A typical warning message has the following form:
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<I>file</I><B>:</B><I>line</I><B>: </B><I>category</I><B>: </B><I>message.</I>
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By default, each warning is printed once for each source line where it
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occurs. This option controls how often warnings are printed.
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Multiple
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<B>-W</B>
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options may be given; when a warning matches more than one
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option, the action for the last matching option is performed.
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Invalid
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<B>-W</B>
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options are ignored (a warning message is printed about invalid
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options when the first warning is issued). Warnings can also be
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controlled from within a Python program using the
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<I>warnings</I>
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module.
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<P>
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The simplest form of
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<I>argument</I>
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is one of the following
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<I>action</I>
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strings (or a unique abbreviation):
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<B>ignore</B>
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to ignore all warnings;
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<B>default</B>
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to explicitly request the default behavior (printing each warning once
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per source line);
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<B>all</B>
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to print a warning each time it occurs (this may generate many
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messages if a warning is triggered repeatedly for the same source
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line, such as inside a loop);
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<B>module</B>
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to print each warning only the first time it occurs in each
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module;
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<B>once</B>
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to print each warning only the first time it occurs in the program; or
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<B>error</B>
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to raise an exception instead of printing a warning message.
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<P>
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The full form of
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<I>argument</I>
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is
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<I>action</I><B>:</B><I>message</I><B>:</B><I>category</I><B>:</B><I>module</I><B>:</B><I>line.</I>
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Here,
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<I>action</I>
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is as explained above but only applies to messages that match the
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remaining fields. Empty fields match all values; trailing empty
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fields may be omitted. The
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<I>message</I>
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field matches the start of the warning message printed; this match is
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case-insensitive. The
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<I>category</I>
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field matches the warning category. This must be a class name; the
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match test whether the actual warning category of the message is a
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subclass of the specified warning category. The full class name must
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be given. The
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<I>module</I>
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field matches the (fully-qualified) module name; this match is
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case-sensitive. The
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<I>line</I>
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field matches the line number, where zero matches all line numbers and
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is thus equivalent to an omitted line number.
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<DT id="20"><B>-x</B>
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<DD>
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Skip the first line of the source. This is intended for a DOS
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specific hack only. Warning: the line numbers in error messages will
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be off by one!
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<DT id="21"><B>-3</B>
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<DD>
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Warn about Python 3.x incompatibilities that 2to3 cannot trivially fix.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>INTERPRETER INTERFACE</H2>
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The interpreter interface resembles that of the UNIX shell: when
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called with standard input connected to a tty device, it prompts for
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commands and executes them until an EOF is read; when called with a
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file name argument or with a file as standard input, it reads and
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executes a
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<I>script</I>
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from that file;
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when called with
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<B>-c</B>
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<I>command</I>,
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it executes the Python statement(s) given as
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<I>command</I>.
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Here
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<I>command</I>
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may contain multiple statements separated by newlines.
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Leading whitespace is significant in Python statements!
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In non-interactive mode, the entire input is parsed before it is
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executed.
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<P>
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If available, the script name and additional arguments thereafter are
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passed to the script in the Python variable
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<I>sys.argv</I>,
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which is a list of strings (you must first
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<I>import sys</I>
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to be able to access it).
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If no script name is given,
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<I>sys.argv[0]</I>
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is an empty string; if
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<B>-c</B>
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is used,
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<I>sys.argv[0]</I>
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contains the string
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<I>'-c'.</I>
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Note that options interpreted by the Python interpreter itself
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are not placed in
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<I>sys.argv</I>.
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<P>
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In interactive mode, the primary prompt is `>>>'; the second prompt
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(which appears when a command is not complete) is `...'.
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The prompts can be changed by assignment to
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<I>sys.ps1</I>
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or
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<I>sys.ps2</I>.
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The interpreter quits when it reads an EOF at a prompt.
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When an unhandled exception occurs, a stack trace is printed and
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control returns to the primary prompt; in non-interactive mode, the
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interpreter exits after printing the stack trace.
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The interrupt signal raises the
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<I>KeyboardInterrupt</I>
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exception; other UNIX signals are not caught (except that SIGPIPE is
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sometimes ignored, in favor of the
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<I>IOError</I>
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exception). Error messages are written to stderr.
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<A NAME="lbAG"> </A>
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<H2>FILES AND DIRECTORIES</H2>
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These are subject to difference depending on local installation
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conventions; ${prefix} and ${exec_prefix} are installation-dependent
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and should be interpreted as for GNU software; they may be the same.
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On Debian GNU/{Hurd,Linux} the default for both is <I>/usr</I>.
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<DL COMPACT>
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<DT id="22"><I>${exec_prefix}/bin/python</I><DD>
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Recommended location of the interpreter.
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</DL>
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<P>
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<I>${prefix}/lib/python<version></I>
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<BR>
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<I>${exec_prefix}/lib/python<version></I>
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<DL COMPACT><DT id="23"><DD>
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Recommended locations of the directories containing the standard
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modules.
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</DL>
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<P>
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<I>${prefix}/include/python<version></I>
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<BR>
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<I>${exec_prefix}/include/python<version></I>
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<DL COMPACT><DT id="24"><DD>
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Recommended locations of the directories containing the include files
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needed for developing Python extensions and embedding the
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interpreter.
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</DL>
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<DL COMPACT>
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<DT id="25"><I>~/.pythonrc.py</I><DD>
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User-specific initialization file loaded by the <I>user</I> module;
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not used by default or by most applications.
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</DL>
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<A NAME="lbAH"> </A>
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<H2>ENVIRONMENT VARIABLES</H2>
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<DL COMPACT>
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<DT id="26">PYTHONHOME<DD>
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Change the location of the standard Python libraries. By default, the
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libraries are searched in ${prefix}/lib/python<version> and
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${exec_prefix}/lib/python<version>, where ${prefix} and ${exec_prefix}
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are installation-dependent directories, both defaulting to
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<I>/usr/local</I>. When $PYTHONHOME is set to a single directory, its value
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replaces both ${prefix} and ${exec_prefix}. To specify different values
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for these, set $PYTHONHOME to ${prefix}:${exec_prefix}.
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<DT id="27">PYTHONPATH<DD>
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Augments the default search path for module files.
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The format is the same as the shell's $PATH: one or more directory
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pathnames separated by colons.
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Non-existent directories are silently ignored.
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The default search path is installation dependent, but generally
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begins with ${prefix}/lib/python<version> (see PYTHONHOME above).
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The default search path is always appended to $PYTHONPATH.
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If a script argument is given, the directory containing the script is
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inserted in the path in front of $PYTHONPATH.
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The search path can be manipulated from within a Python program as the
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variable
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<I>sys.path</I>.
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<DT id="28">PYTHONSTARTUP<DD>
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If this is the name of a readable file, the Python commands in that
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file are executed before the first prompt is displayed in interactive
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mode.
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The file is executed in the same name space where interactive commands
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are executed so that objects defined or imported in it can be used
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without qualification in the interactive session.
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You can also change the prompts
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<I>sys.ps1</I>
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and
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<I>sys.ps2</I>
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in this file.
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<DT id="29">PYTHONY2K<DD>
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Set this to a non-empty string to cause the <I>time</I> module to
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require dates specified as strings to include 4-digit years, otherwise
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2-digit years are converted based on rules described in the <I>time</I>
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module documentation.
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<DT id="30">PYTHONOPTIMIZE<DD>
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If this is set to a non-empty string it is equivalent to specifying
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the <B>-O</B> option. If set to an integer, it is equivalent to
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specifying <B>-O</B> multiple times.
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<DT id="31">PYTHONDEBUG<DD>
|
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If this is set to a non-empty string it is equivalent to specifying
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the <B>-d</B> option. If set to an integer, it is equivalent to
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specifying <B>-d</B> multiple times.
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<DT id="32">PYTHONDONTWRITEBYTECODE<DD>
|
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If this is set to a non-empty string it is equivalent to specifying
|
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the <B>-B</B> option (don't try to write
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<I>.py[co]</I>
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files).
|
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<DT id="33">PYTHONINSPECT<DD>
|
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If this is set to a non-empty string it is equivalent to specifying
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the <B>-i</B> option.
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<DT id="34">PYTHONIOENCODING<DD>
|
|
If this is set before running the interpreter, it overrides the encoding used
|
|
for stdin/stdout/stderr, in the syntax
|
|
<I>encodingname</I><B>:</B><I>errorhandler</I>
|
|
|
|
The
|
|
<I>errorhandler</I>
|
|
|
|
part is optional and has the same meaning as in str.encode. For stderr, the
|
|
<I>errorhandler</I>
|
|
|
|
<BR> part is ignored; the handler will always be 'backslashreplace'.
|
|
<DT id="35">PYTHONNOUSERSITE<DD>
|
|
If this is set to a non-empty string it is equivalent to specifying the
|
|
<B>-s</B> option (Don't add the user site directory to sys.path).
|
|
<DT id="36">PYTHONUNBUFFERED<DD>
|
|
If this is set to a non-empty string it is equivalent to specifying
|
|
the <B>-u</B> option.
|
|
<DT id="37">PYTHONVERBOSE<DD>
|
|
If this is set to a non-empty string it is equivalent to specifying
|
|
the <B>-v</B> option. If set to an integer, it is equivalent to
|
|
specifying <B>-v</B> multiple times.
|
|
<DT id="38">PYTHONWARNINGS<DD>
|
|
If this is set to a comma-separated string it is equivalent to
|
|
specifying the <B>-W</B> option for each separate value.
|
|
<DT id="39">PYTHONHASHSEED<DD>
|
|
If this variable is set to "random", the effect is the same as specifying
|
|
the <B>-R</B> option: a random value is used to seed the hashes of str,
|
|
bytes and datetime objects.
|
|
<P>
|
|
If PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for
|
|
generating the hash() of the types covered by the hash randomization. Its
|
|
purpose is to allow repeatable hashing, such as for selftests for the
|
|
interpreter itself, or to allow a cluster of python processes to share hash
|
|
values.
|
|
<P>
|
|
The integer must be a decimal number in the range [0,4294967295]. Specifying
|
|
the value 0 will lead to the same hash values as when hash randomization is
|
|
disabled.
|
|
</DL>
|
|
<A NAME="lbAI"> </A>
|
|
<H2>AUTHOR</H2>
|
|
|
|
The Python Software Foundation: <A HREF="https://www.python.org/psf/">https://www.python.org/psf/</A>
|
|
<A NAME="lbAJ"> </A>
|
|
<H2>INTERNET RESOURCES</H2>
|
|
|
|
Main website: <A HREF="https://www.python.org/">https://www.python.org/</A>
|
|
<BR>
|
|
|
|
Documentation: <A HREF="file:///usr/share/doc/python2.7/html/index.html">file:///usr/share/doc/python2.7/html/index.html</A> (python-doc package)
|
|
or <A HREF="https://docs.python.org/2/">https://docs.python.org/2/</A>
|
|
<BR>
|
|
|
|
Developer resources: <A HREF="https://docs.python.org/devguide/">https://docs.python.org/devguide/</A>
|
|
<BR>
|
|
|
|
Downloads: <A HREF="https://www.python.org/downloads/">https://www.python.org/downloads/</A>
|
|
<BR>
|
|
|
|
Module repository: <A HREF="https://pypi.python.org/">https://pypi.python.org/</A>
|
|
<BR>
|
|
|
|
Newsgroups: comp.lang.python, comp.lang.python.announce
|
|
<A NAME="lbAK"> </A>
|
|
<H2>LICENSING</H2>
|
|
|
|
Python is distributed under an Open Source license. See the file
|
|
"LICENSE" in the Python source distribution for information on terms &
|
|
conditions for accessing and otherwise using Python and for a
|
|
DISCLAIMER OF ALL WARRANTIES.
|
|
<P>
|
|
|
|
<HR>
|
|
<A NAME="index"> </A><H2>Index</H2>
|
|
<DL>
|
|
<DT id="40"><A HREF="#lbAB">NAME</A><DD>
|
|
<DT id="41"><A HREF="#lbAC">SYNOPSIS</A><DD>
|
|
<DT id="42"><A HREF="#lbAD">DESCRIPTION</A><DD>
|
|
<DT id="43"><A HREF="#lbAE">COMMAND LINE OPTIONS</A><DD>
|
|
<DT id="44"><A HREF="#lbAF">INTERPRETER INTERFACE</A><DD>
|
|
<DT id="45"><A HREF="#lbAG">FILES AND DIRECTORIES</A><DD>
|
|
<DT id="46"><A HREF="#lbAH">ENVIRONMENT VARIABLES</A><DD>
|
|
<DT id="47"><A HREF="#lbAI">AUTHOR</A><DD>
|
|
<DT id="48"><A HREF="#lbAJ">INTERNET RESOURCES</A><DD>
|
|
<DT id="49"><A HREF="#lbAK">LICENSING</A><DD>
|
|
</DL>
|
|
<HR>
|
|
This document was created by
|
|
<A HREF="/cgi-bin/man/man2html">man2html</A>,
|
|
using the manual pages.<BR>
|
|
Time: 00:05:26 GMT, March 31, 2021
|
|
</BODY>
|
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</HTML>
|