PYTHON(1)                                               PYTHON(1)

          python - an interpreted, interactive, object-oriented
          programming language

          python [ -d ] [ -E ] [ -h ] [ -i ] [ -m module-name ] [ -O ]
                 [ -Q argument ] [ -S ] [ -t ] [ -u ]
                 [ -v ] [ -V ] [ -W argument ] [ -x ]
                 [ -c command | script | - ] [ arguments ]

          Python is an interpreted, interactive, object-oriented pro-
          gramming language that combines remarkable power with very
          clear syntax.  For an introduction to programming in Python
          you are referred to the Python Tutorial.  The Python Library
          Reference documents built-in and standard types, constants,
          functions and modules.  Finally, the Python Reference Manual
          describes the syntax and semantics of the core language in
          (perhaps too) much detail.  (These documents may be located
          via the INTERNET RESOURCES below; they may be installed on
          your system as well.)

          Python's basic power can be extended with your own modules
          written in C or C++.  On most systems such modules may be
          dynamically loaded.  Python is also adaptable as an exten-
          sion language for existing applications.  See the internal
          documentation for hints.

          Documentation for installed Python modules and packages can
          be viewed by running the pydoc program.

          -c command
               Specify the command to execute (see next section).
               This terminates the option list (following options are
               passed as arguments to the command).

          -d   Turn on parser debugging output (for wizards only,
               depending on compilation options).

          -E   Ignore environment variables like PYTHONPATH and
               PYTHONHOME that modify the behavior of the interpreter.

          -h   Prints the usage for the interpreter executable and

          -i   When a script is passed as first argument or the -c
               option is used, enter interactive mode after executing
               the script or the command.  It does not read the
               $PYTHONSTARTUP file.  This can be useful to inspect

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     PYTHON(1)                                               PYTHON(1)

               global variables or a stack trace when a script raises
               an exception.

          -m module-name
               Searches sys.path for the named module and runs the
               corresponding .py file as a script.

          -O   Turn on basic optimizations.  This changes the filename
               extension for compiled (bytecode) files from .pyc to
               .pyo.  Given twice, causes docstrings to be discarded.

          -Q argument
               Division control; see PEP 238.  The argument must be
               one of "old" (the default, int/int and long/long return
               an int or long), "new" (new division semantics, i.e.
               int/int and long/long returns a float), "warn" (old
               division semantics with a warning for int/int and
               long/long), or "warnall" (old division semantics with a
               warning for all use of the division operator).  For a
               use of "warnall", see the Tools/scripts/

          -S   Disable the import of the module site and the site-
               dependent manipulations of sys.path that it entails.

          -t   Issue a warning when a source file mixes tabs and
               spaces for indentation in a way that makes it depend on
               the worth of a tab expressed in spaces.  Issue an error
               when the option is given twice.

          -u   Force stdin, stdout and stderr to be totally
               unbuffered.  On systems where it matters, also put
               stdin, stdout and stderr in binary mode.  Note that
               there is internal buffering in xreadlines(), read-
               lines() and file-object iterators ("for line in
               sys.stdin") which is not influenced by this option.  To
               work around this, you will want to use
               "sys.stdin.readline()" inside a "while 1:" loop.

          -v   Print a message each time a module is initialized,
               showing the place (filename or built-in module) from
               which it is loaded.  When given twice, print a message
               for each file that is checked for when searching for a
               module.  Also provides information on module cleanup at

          -V   Prints the Python version number of the executable and

          -W argument
               Warning control.  Python sometimes prints warning mes-
               sage to sys.stderr. A typical warning message has the

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     PYTHON(1)                                               PYTHON(1)

               following form: file:line: category: By default, each
               warning is printed once for each source line where it
               occurs.  This option controls how often warnings are
               printed.  Multiple -W options may be given; when a
               warning matches more than one option, the action for
               the last matching option is performed.  Invalid -W
               options are ignored (a warning message is printed about
               invalid options when the first warning is issued).
               Warnings can also be controlled from within a Python
               program using the warnings module.

               The simplest form of argument is one of the following
               action strings (or a unique abbreviation): ignore to
               ignore all warnings; default to explicitly request the
               default behavior (printing each warning once per source
               line); all to print a warning each time it occurs (this
               may generate many messages if a warning is triggered
               repeatedly for the same source line, such as inside a
               loop); module to print each warning only the first time
               it occurs in each module; once to print each warning
               only the first time it occurs in the program; or error
               to raise an exception instead of printing a warning

               The full form of argument is action:message:category:
               Here, action is as explained above but only applies to
               messages that match the remaining fields.  Empty fields
               match all values; trailing empty fields may be omitted.
               The message field matches the start of the warning mes-
               sage printed; this match is case-insensitive.  The
               category field matches the warning category.  This must
               be a class name; the match test whether the actual
               warning category of the message is a subclass of the
               specified warning category.  The full class name must
               be given.  The module field matches the (fully-
               qualified) module name; this match is case-sensitive.
               The line field matches the line number, where zero
               matches all line numbers and is thus equivalent to an
               omitted line number.

          -x   Skip the first line of the source.  This is intended
               for a DOS specific hack only.  Warning: the line num-
               bers in error messages will be off by one!

          The interpreter interface resembles that of the UNIX shell:
          when called with standard input connected to a tty device,
          it prompts for commands and executes them until an EOF is
          read; when called with a file name argument or with a file
          as standard input, it reads and executes a script from that
          file; when called with -c command, it executes the Python
          statement(s) given as command. Here command may contain

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     PYTHON(1)                                               PYTHON(1)

          multiple statements separated by newlines.  Leading whites-
          pace is significant in Python statements!  In non-
          interactive mode, the entire input is parsed before it is

          If available, the script name and additional arguments
          thereafter are passed to the script in the Python variable
          sys.argv , which is a list of strings (you must first import
          sys to be able to access it).  If no script name is given,
          sys.argv[0] is an empty string; if -c is used, sys.argv[0]
          contains the string '-c'. Note that options interpreted by
          the Python interpreter itself are not placed in sys.argv.

          In interactive mode, the primary prompt is `>>>'; the second
          prompt (which appears when a command is not complete) is
          `...'.  The prompts can be changed by assignment to sys.ps1
          or sys.ps2. The interpreter quits when it reads an EOF at a
          prompt.  When an unhandled exception occurs, a stack trace
          is printed and control returns to the primary prompt; in
          non-interactive mode, the interpreter exits after printing
          the stack trace.  The interrupt signal raises the Keyboard-
          Interrupt exception; other UNIX signals are not caught
          (except that SIGPIPE is sometimes ignored, in favor of the
          IOError exception).  Error messages are written to stderr.

          These are subject to difference depending on local installa-
          tion conventions; ${prefix} and ${exec_prefix} are
          installation-dependent and should be interpreted as for GNU
          software; they may be the same.  The default for both is

               Recommended location of the interpreter.

               Recommended locations of the directories containing the
               standard modules.

               Recommended locations of the directories containing the
               include files needed for developing Python extensions
               and embedding the interpreter.

               User-specific initialization file loaded by the user
               module; not used by default or by most applications.


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     PYTHON(1)                                               PYTHON(1)

               Change the location of the standard Python libraries.
               By default, the libraries are searched in
               ${prefix}/lib/python<version> and
               ${exec_prefix}/lib/python<version>, where ${prefix} and
               ${exec_prefix} are installation-dependent directories,
               both defaulting to /usr/local.  When $PYTHONHOME is set
               to a single directory, its value replaces both ${pre-
               fix} and ${exec_prefix}.  To specify different values
               for these, set $PYTHONHOME to ${prefix}:${exec_prefix}.

               Augments the default search path for module files.  The
               format is the same as the shell's $PATH: one or more
               directory pathnames separated by colons.  Non-existent
               directories are silently ignored.  The default search
               path is installation dependent, but generally begins
               with ${prefix}/lib/python<version> (see PYTHONHOME
               above).  The default search path is always appended to
               $PYTHONPATH.  If a script argument is given, the direc-
               tory containing the script is inserted in the path in
               front of $PYTHONPATH.  The search path can be manipu-
               lated from within a Python program as the variable
               sys.path .

               If this is the name of a readable file, the Python com-
               mands in that file are executed before the first prompt
               is displayed in interactive mode.  The file is executed
               in the same name space where interactive commands are
               executed so that objects defined or imported in it can
               be used without qualification in the interactive ses-
               sion.  You can also change the prompts sys.ps1 and
               sys.ps2 in this file.

               Set this to a non-empty string to cause the time module
               to require dates specified as strings to include 4-
               digit years, otherwise 2-digit years are converted
               based on rules described in the time module documenta-

               If this is set to a non-empty string it is equivalent
               to specifying the -O option. If set to an integer, it
               is equivalent to specifying -O multiple times.

               If this is set to a non-empty string it is equivalent
               to specifying the -d option. If set to an integer, it
               is equivalent to specifying -d multiple times.


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     PYTHON(1)                                               PYTHON(1)

               If this is set to a non-empty string it is equivalent
               to specifying the -i option.

               If this is set to a non-empty string it is equivalent
               to specifying the -u option.

               If this is set to a non-empty string it is equivalent
               to specifying the -v option. If set to an integer, it
               is equivalent to specifying -v multiple times.

          The Python Software Foundation:

          Main website:
          Community website:
          Developer resources:
          Module repository:
          Newsgroups:  comp.lang.python, comp.lang.python.announce

          Python is distributed under an Open Source license.  See the
          file "LICENSE" in the Python source distribution for infor-
          mation on terms & conditions for accessing and otherwise
          using Python and for a DISCLAIMER OF ALL WARRANTIES.

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